Before you begin this course, make sure you skim through the Course Orientation (see the "Orientation" menu).
My training is in research science, not education. One of my objectives in this lesson is to find out what your opinions are about teaching science and the state of science education in general. I also want you to practice reading articles, discussing them with the class, and making plots. These are all skills that you'll need later on in the course and in the other courses in this program.
By the end of Lesson 1, you should be able to:
Lesson 1 will take us one week to complete. 26 Aug - 3 Sep 2019.
Requirement | Submitted for grading? | due date |
---|---|---|
Read articles and discuss them with the class | Yes—Your discussion board participation counts toward your Lesson 1 grade | regular participation spanning 26 Aug - 3 Sep |
Map yourself | No-Optional but fun! Place yourself on a map of current and former M.Ed. in Earth Sciences students and faculty | |
Create plots of data sets | Yes—This exercise will be submitted to a Canvas assignment and will count toward your Lesson 1 grade | 3 Sep |
Pre-instructional quiz | Yes—Taking this Canvas-based quiz will count toward your Lesson 1 grade (you will not be graded on the correctness of your responses, only on whether you answered all the questions) | 3 Sep |
If you have any questions, please post them to our Questions? discussion forum in Canvas (not e-mail). I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
To begin, I would like you to read two articles and discuss their merits with the rest of the class in a discussion forum. This discussion will last throughout the week, so be sure to read the articles early and check in to the discussion forum often. See the Lesson 1 Overview page for specific dates.
Read the following articles, which are linked directly from the Lesson 1 Paper Discussion board in Canvas.
Once you have finished the readings, engage in a class discussion as described below. This discussion will take place over the entire week devoted to Lesson 1 and will require you to participate multiple times over that period.
You will be graded on the quality of your participation. Please see the rubric for teaching/learning discussions. [1]
Please follow the instructions below to place a pin on the map indicating where you live.
When you have your students make plots of data in your classes, what medium do they use? Do they use a computer program, a graphing calculator, or pencil and paper? Something else? I actually find pencil and paper to be extremely instructive. When I use a pencil and paper, it means I have to think about how to draw my axes and what the plot will probably look like before I begin. However, I think we all expect our own students to be a little savvier about computer use than we were at their age (even though they might not be -- they just think they are!). When I make plots for my research I use Processing, MATLAB or sometimes Numbers. I expect many of you have access to or regularly use Microsoft Excel. (I find that most plots produced in Excel look ugly or have incomprehensible labels, or both. However, if you can make a good plot with Excel, go for it! If you don't know what I mean by good, then don't use Excel.)
On the next page of this lesson, you will complete an activity that involves reproducing three plots using the graphing program of your choice. For this course, it does not matter to me what program you choose to use. What does matter to me is that you are able to generate a dataset and make a plot of it that looks adequate for a 500-level college class. So first, you need to figure out which program you would like to use! If you already have a program you like to use, by all means, use it. If you don't, or you want to check out some other possibilities, here are some links to other programs.
It is also okay with me if you like to make your plots by hand, but you do have to have some way to submit them electronically. Also, later on in the course you will have to make plots of large datasets and in that case, the tedium of setting 100+ points by hand outweighs the instructiveness of that method, I think. So why not bite the bullet and check out some of the programs below.
Now that you have identified the software you want to use to create plots of datasets, I want you to reproduce three plots and submit these to me for review.
This activity will be graded based on participation only (either you made three plots or you didn't). I will provide constructive feedback to you about the way your plots look. Even though I will not grade this particular exercise for accuracy, the rest of the lessons in this course (as well many lessons in other courses in the program) will require you to make some plots. Your grades on those activities will in part depend on your ability to produce a clear and satisfactory plot, so consider this exercise free practice.
Below is the first plot you have to reproduce. Graph the functions y = x2 and y = 2x on the same set of axes. The satisfactory plot will include a title, labeled axes, axes' tick marks and labels, two different line styles (doesn't have to be color) to differentiate the functions, and a correct legend identifying the two functions. All fonts should be large enough to be legible. You may choose the range of your axes, the aspect ratio of your plot, and the line style of each function.
Number of PSU touchdowns | Number of fans at the Big House |
---|---|
0 | 109,901 |
1 | 54,950 |
2 | 27,475 |
3 | ? |
4 | ? |
5 | ? |
This plot should be made on linear axes. The satisfactory plot will include a title, labeled axes, axes' tick marks, and labels. Since you are plotting discrete data points that are part of a time series, please plot them with a symbol and connect the symbols with a line. All fonts should be large enough to be legible. You may choose the aspect ratio of your plot and what kind of symbol and line style to use.
You may choose to submit these plots one of two ways: you may save them as graphics files (.jpg, .pdf or .tiff) or, if you use a web plotting program that allows you to save your plot as a link, then you may submit the links to the plots.
Save your three plots in the following format:
L1_plot1_AccessAccountID_LastName.jpg (or .png or .pdf or .tiff).
For example, Cardinals outfielder Marcell Ozuna's file would be named "L1_plot1_mio13_ozuna.jpg"
Submit your three plots to the Canvas assignment in Preinstructional Activities called "Three Plots." Try to get this done by the due date listed on the first page of this lesson.
As I mentioned at the top of the page, this activity will be graded based on participation only (either you made three plots or you didn't). However, I will provide constructive feedback to you about your plots.
Go to Canvas and take the "Pre-instructional background quiz," which you can find in the Pre-instructional Activities module.
The quiz is entirely self-contained in Canvas. When you submit your quiz, it will be shared with me.
This quiz is NOT graded for accuracy, only for participation. I just want to get a sense of your Earth science background, relevant to the lessons we'll cover in this course. You should get feedback right away, but don't worry if Canvas gives you a bad grade. I will go to the gradebook and override it. Just read the feedback and you'll be fine. Try to get it done by the due date listed on the first page of this lesson.
Okay, enough with the background stuff, let's move on to Lesson 2 and do some science!
You have finished Lesson 1. Double-check the list of requirements on the Lesson 1 Overview page to make sure you have completed all of the activities listed there before beginning the next lesson.
The figure below, from NOAA's Pacific Marine Environmental Laboratory, shows global maximum wave amplitudes from the tsunami caused by the great 26 December 2004 Sumatra-Andaman earthquake. In Lesson 2 we will analyze tide gauge records from this event and from the 2011 Tohoku-Oki tsunami.
The results of this analysis will inform our subsequent discussion of the potential for tsunami risk in the Atlantic Ocean. Finally, we will determine the advantages and disadvantages of developing a tsunami warning system in the Atlantic Ocean.
I first found out that the 26 December 2004 Sumatra-Andaman earthquake had happened while watching the news at my brother-in-law's house where we were visiting for Christmas. Several scientists from universities on the East Coast of the U.S. were interviewed, and more than one of them wanted to highlight the fact that the Atlantic Ocean doesn't have a dedicated tsunami warning system. They were pretty sure the Atlantic Ocean should have one. What do you think? By the end of this lesson, I want you to present your informed opinion about this. In order to make sure your opinion is an informed one, we'll examine tsunami generation, look at some data from the Sumatra-Andaman tsunami and the Tohoku-Oki tsunami and become conversant with the risks associated with tsunamis and how tsunami warning systems work.
All of the tsunami warning sign icons you will see in this lesson are from the Pacific Tsunami Museum [13]
By the end of Lesson 2, you should be able to:
As you work your way through Lesson 2, you will encounter reading assignments and hands-on exercises using authentic data. The chart below provides an overview of the requirements for Lesson 2.
Lesson 2 will take us two weeks to complete: 4 -17 Sep 2019. You should complete the reading assignments by the end of the first week to give you time for thoughtful participation in the discussions. The problem set is due at the end of the first week of the lesson, and you will submit it to a Canvas assignment. This will give you the entire second week of the lesson to participate in the discussion forum and to pull together what you've learned so you can write the paper that is the culminating assignment for this lesson.
Requirement | Submitted for grading? | Due Date |
---|---|---|
Read two articles: "N.E. is not immune, scientists warn", "Cumbre Vieja Volcano -- Potential collapse and tsunami at La Palma, Canary Islands" | No | 10 Sep |
Exercise: "Where are tsunamigenic danger zones located? | No | 10 Sep |
Read two articles: "Learning from Natural Disasters", "Global Seismographic Network Records the Great Sumatra-Andaman Earthquake" | No | 10 Sep |
Tsunami data problem set | Yes—Submitted to the "Tsunami data problem set" assignment in Canvas | 10 Sep (end of week 1) |
Paper assignment | Yes—Submitted to the "Tsunami Warning System Paper" assignment in Canvas | 17 Sep (end of week 2) |
Discussion: "Teaching and learning about tsunamis" | Yes—Posted to the "Teaching and Learning About Tsunamis" discussion in Canvas |
participation spanning 11 - 17 Sep (week 2) |
If you have any questions, please post them to our Questions? discussion (not e-mail). I will check that discussion daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
First, I would like you to read an article that appeared in The Boston Globe following the Sumatra-Andaman earthquake. Then, please read a short scientific paper detailing the tsunami threat from a source in the Canary Islands.
Daley, B. (2007, December 28). N.E. is not immune, scientists warn [14]. The Boston Globe. Retrieved April 22, 2008, from http://www.boston.com/news/world/articles/2004/12/28/ne_is_not_immune_scientists_warn/.
Ward, S., & Day, S. (2001). Cumbre Vieja Volcano -- Potential collapse and tsunami at La Palma, Canary Islands [15]. Geophysical Research Letters, 28, 397-400. (See also a press release from The Independent [16] that accompanies the scientific article.)
The first article nicely introduces the topic for this lesson, which is whether or not you think a dedicated tsunami warning system should be developed for the Atlantic Ocean. The main reason I want you to read this article is that it brings up some topics that we will want to delve into further as this lesson goes along.
When you read the first article, keep in mind the following:
The second article is a scientific paper published in a journal. When you read this paper, keep in mind the following:
These articles do not answer all these questions, but these are the questions that I would ask if I read them without knowing anything else. What other questions do you have after reading these articles? Please post any questions to the Questions? discussion board in Canvas.
If we are going to attempt to assess the risk of a tsunami at some particular place on the planet, we must first understand how to make a tsunami. Earthquakes and volcanoes generate the great majority of tsunamis, and the theory of plate tectonics explains the cause of earthquakes and volcanoes. So, we'll start with the world's briefest review of plate tectonics. Plate tectonics is the Grand Unifying Theory of geosciences, but it's actually not that old. In fact, my freshman advisor in college wrote the benchmark paper that outlined the mathematical model of plate tectonics, so in a sense, I'm only one "generation" removed from the pre-plate tectonics era. **Shameless plug alert**: For an in-depth look at the history of the theory of plate tectonics, take EARTH 520.
The Earth's lithosphere is broken up into a bunch of discrete pieces, called plates, that move around the surface of the planet. This motion is driven by the flow of the mantle rock beneath the plates and by the forces plates exert at their boundaries where they touch each other. There are three distinct types of plate boundaries, shown illustrated by the drawing below both as separate block diagrams as well as situated within their appropriate geologic environment.
Earthquakes happen when plates move with respect to each other because the friction and stress at the edges of plates prevent them from slipping smoothly at their boundaries. For an earthquake to generate a tsunami you need:
If an earthquake happens far away from a body of water, it probably won't disturb the water too much. Therefore, no tsunami is expected. Next, you need a vertical disturbance. Picture this: You have a bathtub full of water and a hard-backed book. If you dip the book into the bathwater spine-first and move the book back and forth longways, what do you observe? Not much, except you've ruined your book. Now if you hold the book with its flat side on the surface of the water and move the book up and down in the water, you should generate some big waves as the vertical motion you've imposed on the water column is transferred to horizontal motion as the wave travels away from the source. This is basically how a tsunami is generated.
If "The Big One" happens on the San Andreas Fault, do we expect a large tsunami? Do we expect California to "fall into the ocean" as in the cartoon I drew? Think about why or why not based on the material you just read
Volcanic eruptions can also produce tsunamis. The rules are similar to the rules for earthquakes. In order for a volcano to produce a tsunami you need:
1. A volcano near the coast
2. An eruption that sends a large enough volume of material into the water to displace a significant volume of water.
If a large eruption sends a great volume of material into the water, it creates the vertical disturbance necessary to make a tsunami. This is one of the reasons the Cumbre Vieja volcano is worrisome: either an eruption or a landslide from a flank collapse could produce a tsunami.
Want to learn more about volcanoes and tsunamis? One of the earliest modern records of a devastating tsunami comes from the eruption of Krakatoa in August 1883. Read about that tsunami on the BBC News site - Krakatoa: The first modern tsunami. [18]
Now that we know earthquakes and volcanoes are the biggest sources of tsunamis, let's find on a map of the world where these tsunamigenic danger zones are located.
You do NOT need to submit the following activity, but doing it will help you visualize where the greatest potential tsunamigenic areas are on the globe. This will aid your thinking about your culminating assignment for this lesson.
- Which of the world's coastlines are most at risk for tsunamis? Does this shed light on where today's tsunami warning systems exist already?
- What tsunamigenic sources would affect the Atlantic coastlines? Where are they located?
There is nothing to submit for this assignment. However, feel free to post any questions or thoughts you may have about this activity to the Questions? Discussion Board in Canvas.
We are going to work with some tsunami data from the 26 December 2004 Sumatra-Andaman earthquake and from the 11 March Tohoku-Oki earthquake. Before we do so, I want you to get a sense about the scientific community's study of those earthquakes, so I've picked a couple of articles that describe the techniques used to record the earthquakes and what we have learned so far.
The following articles are all linked from Lesson 2 in Canvas or through the links provided.
Interested in learning more? "Anatomy of a Tsunami" [25] is an interactive flash movie from Teachers' Domain and Nova Online about the Sumatra-Andaman tsunami.
"Teacher's Domain" is a free resource, but you must register with them in order to view more than 7 resources. If you like their stuff you may want to take a moment to go ahead and register with them now.
In the following analysis, you'll work with tide gauge records from stations around the world that recorded the tsunami generated by the 26 December 2004 Sumatra-Andaman earthquake. Then you will work with data recorded by Pacific Ocean DART stations from the 2011 Tohoku-Oki earthquake. It is fine with me to complete this analysis in whatever way works best for you. You may all work together to do this activity or you may want to work in groups or by yourselves. No matter how you choose to go about it, please write up and submit your analyses individually and in your own words. This activity is due at the end of the first week of this lesson.
Save the Tide Gauges Problem Set Worksheet [26] to your computer by right-clicking (control-click on a Mac) on the link above and selecting "Save link as..."
You should use the worksheet for writing down your answers but you should leave this web page open while you work on the problem set. WHY? Because I explain how to do most of the analysis right here. The worksheet is just so you don't have to retype the questions yourself.
Below are four record sections. These data come from tide gauges maintained by the University of Hawaii with support from NOAA. Review each record section, then answer the associated questions on your worksheet.
Before you begin, let's look at Salalah's record together [27]:
1.1 The latitude and longitude of this station are given in degrees and minutes. (i.e. 15-56 N means 15° 56' North latitude and 54-00 E means 54° 00' East longitude). Each degree contains 60 minutes. For later calculations, we will want to use decimal degrees instead of minutes. Convert the latitude and longitude of this station to decimal degrees. HINT for getting started: If the latitude were 12-13 N, meaning 12° 13' N, this would equal 12.22° because 13/60 = 0.22.
1.2 Let’s look at the axes and data now. The X-axis is showing time and the Y-axis is showing water height. The X-axis ranges from 26 to 31. These are days of December 2004. The Y-axis ranges from -200 to +200 cm. Now let's look at what is being plotted here. The black line connects data measurements shown by small black dots. The red line is a prediction of the tidal signature at this station. Okay, what are the obvious things to see here? You should be able to discern the approximate arrival time of the tsunami. When is it? Where on this record is the prediction of wave height doing a good job and where is it failing? Why does the prediction fail where it does? For about how long does the tsunami have a significant impact on the wave height at this station?
1.3 Look at the background tidal signature. Describe the tidal cycle for one 24-hour period.
1.4 What is the normal tidal amplitude? Compare this with the amplitude of the tsunami. Keep in mind that the tsunami amplitude is superimposed on top of the tidal signature.
This record looks a lot different from the record at the Salalah station. This is an analog recording made with a pen connected to a cylindrical paper drum that turns continuously at a set pace. It doesn't take much perusing to see why digital data is preferred for most scientific measurements. For one thing, if somebody doesn't come along and change the paper every 24 hours, the record of each successive day prints over the record of the previous day as the tidal cycles repeat. On the other hand, I think this record looks really cool. There's something about analog records that just seem more lifelike. They aren't totally useless, either. What can we find out from inspecting this record? First, let's look at it together [28], then you can answer the questions.
1.5 The time scale on the X-axis is given up in the right-hand corner of the record. It says "Time scale: 1 line = 10 minutes (1 sheet = 1 day)". Okay, so take a look at the grid. What do the numbers on the X-axis refer to? How many days are shown in this record?
1.6 The vertical scale is given. (It's floating in the middle of the record.) What is the normal tidal amplitude at this station?
1.7 Comment on the differences you note between the tidal cycle at this station and at the Salalah station. Comment on the differences you note between the normal tidal amplitude here and at Salalah and the differences between the tsunami amplitude at this station compared to the Salalah station. Why are there differences?
1.8 Notice that because of the fact that more than one day is shown on this record, you can see that the tidal peaks and troughs are offset slightly as the days go by. Tides do not have a period that fits exactly into one day. That is, the peak-to-peak time is not exactly 12 hours. Approximately what is the period? (If you live near the coast, or have spent any time near the ocean, you already knew that the time of the high and low tides change predictably as the days go by. Isn't it reassuring when recorded data confirms what an observant person already knows! Science works!)
1.9 When does the tsunami arrive at Ranong? What is the amplitude of the tsunami compared to the background tidal amplitude? For about how long does the tsunami affect sea level height at Ranong? Compare these answers with your observations of the records from Salalah station.
I think you should now be able to interpret this plot on your own. Try it!
1.10 The coordinates of this station are given in degrees, minutes, and seconds. There are 60 minutes in each degree and 60 seconds in each minute. Convert the station coordinates to decimal degrees.
1.11 The local time at this station is "UTC +3". This means that this station is three hours ahead of "Universal time", which is set for historical reasons at Greenwich, England, where the longitude is zero. Find out the difference between UTC and the time in your hometown. (Your computer probably knows. Otherwise, a quick web search should accomplish this task.) Remember to cite the place where you found the answer.
1.12 What are the units of the X and Y axis on this record?
1.13 When does the tsunami arrive?
1.14 What is the tsunami amplitude compared to the normal tidal amplitude? Compare this to your observations at the previous stations.
HMM! What is going on at this station? The red line shows the tidal prediction and the black and blue lines show data.
1.15 The latitude and longitude are given for this station in degrees and minutes. Convert to decimal degrees.
1.16 The X-axis is given in "Julian days" of 2004. Julian days are numbered consecutively from 1 to 365 (or 366 in leap years). So January 1 is Julian day 001, February 1 is Julian day 032. What is the Julian day of your birthday? Convert the values of the X-axis from Julian days to normal dates. (To get this answer, you have to recall whether 2004 was a leap year or not.)
1.17 Read the text given by the spelling-challenged station operator as part of this record section. Now, look at the data records. When does the tsunami arrive? What happens to the data at this point? Why does the red line continue uninterrupted?
This is probably a good time to point out that data isn't always perfect. Sometimes hardware fails, as in this case. Sometimes errors and uncertainties are introduced in other ways. We will discuss measurement error and uncertainty more fully in the next part of the problem set.
You have finished Part 1 of this problem set! Proceed to Part 2 on the next page.
On 2011/3/11 near Honshu Island, Japan (38.322°N, 142.369°E) at 5:46:23 (UTC), a magnitude 9 earthquake occurred. You will inspect the records of 13 DART stations that recorded the tsunami, use them to calculate the speed of the tsunami, plot the stations and the earthquake on a world map, and then answer a set of questions about the data and your observations. For this part of the problem set, I downloaded the freely available data and made the plots for you. Later in this class, you'll have to do the data processing yourself, but not this time. If you want to check the raw data out and see a nice map, this is where to go: 2011 Tohoku Japan DART Data [29]
Use "Part 2" of your problem set worksheet to record your work. View the DART station records for this activity [30]. You can also click on the thumbnails in the table below to see each station's data separately.
In general, you don't have to write a whole page of calculations for each station like I do in my examples, I just wanted to be thorough so you can see my procedure. On the other hand, if you don't show any work it is harder for me to give you partial credit if you make a mistake (see my grading rubric, below).
2.0 Using Google Maps, make a map of the location of both earthquakes, the tide gauge stations from Part 1, and the DART stations from Part 2. When you are done with your map, save it, make a link to it, and paste the link into your worksheet. Or you can take a screenshot of your map and insert that into your worksheet.
2.1 You already worked with Julian days in Part 1. Now we are going to work with time as expressed in fractions of a day. The earthquake happened on 2011/3/11 at 5:46:23. What is the Julian day of this time, exactly, as expressed in decimal form?
2.2 Look at each station record and pick the arrival time of the tsunami. I have done the first one for you. Make sure you pick the arrival time of the tsunami and not the arrival time of the seismic waves. Fill in your answers in the table.
2.3 Calculate the tsunami travel time to each station by subtracting the origin time from the arrival time. (Now aren’t you glad you converted the origin time to decimals!!). I’ve done the first one for you. Your answers will be in fractions of a day, so convert to hours. Fill in your answers in the table.
2.4 Calculate the epicenter-to-station distance along the great circle path between the two locations. We use the great circle path formula because we are calculating distance on the surface of a sphere. Here is the formula for great circle distance: cos(d) = sin(a)sin(b) + cos(a)cos(b)cos|c| in which d is the distance in degrees, a and b are the latitudes of the two points and c is the difference between the longitudes of the two points. Multiply the answer by 111.32 to get from degrees to kilometers. Jean-Paul Rodrigue, at Hofstra University, gives an excellent explanation and tutorial of how to calculate the distance along a great circle path [32]. I’ve done the first one for you. Fill in your answers in the table.
A nice website that will calculate great circle distance for you [33].
2.5 Calculate the tsunami speed. To get the speed, you use the formula speed = distance/time. I’ve done the first one for you. Fill in your answers in the table.
2.6 I want you to think about the uncertainties in the calculations you performed in determining tsunami velocity. One obvious source of uncertainty is measurement precision at each tide gauge station. For example, let’s say that you are working with a DART station that takes a measurement every 15 minutes. This means that picking the arrival time of the tsunami can't be more precise than this. Go back and change the arrival time pick for Station 21418 and for Station 32412 each by 15 minutes. Now recalculate the speed of the tsunami for each of those two stations. How much has your answer changed for each one? Which one is affected more by the uncertainty in arrival time and why?
2.7 What are some other sources of uncertainty in these calculations?
2.8 Calculate the mean speed for the tsunami. Are you surprised by this speed? How does this speed compare to a jet airplane? an Indy car? a bullet fired from a gun? an earthquake P wave? a major league fastball? Pick several items that interest you (they don't have to be any of the examples above if you don't like those) and compare them to the speed of the tsunami.
2.9 Tsunami speed is controlled by water depth. In fact tsunami speed equals the square root of the product of water depth and g, the gravitational constant (9.8 m/s2). Calculate the mean water depth of the Pacific Ocean. To do this, use the mean speed of the tsunami that you calculated in 2.8, convert it from km/hr to m/s, then plug into the equation speed=sqrt(depth*g).
2.10 I want you to think about approaching the question of tsunami speed from a different perspective. What if you wanted to determine how fast a hypothetical tsunami could get from point A to point B? List what would you need to know to make this calculation.
2.11 Now try it! Let's say a large earthquake happens in the Pacific Northwest, approximately at the location of Seattle, generating a tsunami. Determine how long it would take the tsunami to arrive in Hilo, Hawaii.
2.12 What are the sources of uncertainty in the calculation you just did in the previous question?
2.13 There are definitely tide gauge stations on the west coast of Japan and they recorded the tsunami as well. However, we did not use any data from those stations to calculate the speed of the tsunami or to calculate the mean water depth between the earthquake and those stations. Why not? (In order to answer this question you will need to look at the map you made and think about what assumptions we made to do our calculations.)
Save your worksheet as a Microsoft Word, PDF, or Pages file in the following format:
L2_TsunamiData_AccessAccountID_LastName.doc (or .pdf or .pages).
For example, Cardinals' shortstop Jhonny Peralta's file would be named "L2_TsunamiData_jap27_peralta.doc"
Upload your worksheet to the Tsunami Data problem set assignment in Canvas by the due date on the first page of this lesson.
I will use my general grading rubric for problem sets [47] when I grade this activity.
So far we've talked about the physics of tsunamis and you have investigated tsunami data and made some calculations about tsunami speeds. What's the current state of the art in terms of tsunami risk and hazard mitigation? Where are some other sites in the Atlantic Ocean where tsunamigenic potential lurks?
The following readings are either freely available online if they are linked from this page, or if they are not in the public domain then they are linked from Canvas. You should at least skim these articles because they deal with potential Atlantic Ocean tsunamigenic sites.
The following readings will help you become conversant with the way tsunami warning systems work, and what has been done since the 2004 Sumatra-Andaman tsunami:
Your final task for this lesson is to write a paper. This assignment is due at the end of this lesson. The "Additional Resources" page for this lesson contains some links to articles and Web sites that you may find helpful. You are in no way limited to those resources, however.
PDF Download of Directions [55]
Write a paper that defends or attacks the following statement: The nations surrounding the Atlantic Ocean should cooperate to form a tsunami warning system for the Atlantic Ocean.
The successful paper should meet the following criteria:
I expect your essay to be well organized and coherent, with a thesis statement at the beginning of the essay; topic statements at the beginning of every paragraph; smooth transitions between paragraphs and ideas; few or no grammatical and spelling errors; and properly cited, detailed explanations of the results of scientific studies to back up every assertion you make.
As the reader, I should both understand what you are talking about and be convinced that you have made a strong argument for your case. It should be clear to me that you understand the significance of the results of all the scientific studies you refer to in your paper (including your own). See grading rubric below for more details. Your grade will be dependent upon all of these elements. Content and organization are the most important elements, but if your grammatical/syntax errors are significant enough to distract me from the content of your argument, then this will affect your grade. Make sure you read the assignment carefully and understand it before you begin.
Upload your paper to the "Tsunami Warning System Paper" assignment in Canvas. The due date for this paper is given in the assignment table on the first page of this lesson.
If you cringe and procrastinate at the thought of writing a paper, then you may submit this assignment in the following way instead. You may use the Prezi program to create an interesting presentation of your persuasive essay. Prezi [56] is a free web tool.
The Prezi website explains how to use their tool so I won't try to do it for them.
If you choose this option:
Let's take some time to reflect on what we've covered in this lesson!
For this activity, I want you to reflect on what we've covered in this lesson and to consider how you might adapt these materials to your own classroom. Since this is a discussion activity, you will need to enter the discussion forum more than once in order to read and respond to others' postings. The discussion will take place during the second week of this lesson.
You will be graded on the quality of your participation. Please see the rubric for teaching/learning discussions. [1]
Various Web site with links to resources about tsunamis aimed at teachers and students:
Links to other Web sites
A short video about the 1964 Good Friday earthquake in Alaska and the tsunami it generated. This video was produced by students in my 2011 PSU freshman seminar on historic great earthquakes.
Other papers and articles of interest
Atwater et al., 2005, The Orphan Tsunami of 1700—Japanese Clues to a Parent Earthquake in North America, USGS Professional Paper 1707
Have another Web site on this topic that you have found useful? Share it in our Questions discussion forum in Canvas!
In this lesson, you studied the catastrophic effects of a tsunamigenic earthquake and evaluated the potential risks posed by tsunamis in other parts of the world. One of the obstacles faced by those who make a living trying to assess risk and mitigate the hazards posed by geologic activity is that the timescale in between potential disasters in a specific location (e.g., large earthquakes or volcanic eruptions) is often too long for humans to have accurate statistical measurements of how often it might happen. This makes reconciling the cost of preparedness with scientific accuracy a little tricky. In the next lesson, we'll study this problem in a place that is potentially hazardous for earthquakes.
You have reached the end of Lesson 2! Double-check the list of requirements on the Lesson 2 Overview page to make sure you have completed all of the activities listed there.
The figure below shows a simplified geologic cross-section of an impact crater in Chicxulub, Mexico. This crater is thought by most scientists to be the impact crater resulting from the asteroid collision that caused the mass extinction event at the end of the Mesozoic era about 65 million years ago. In this lesson, we will discuss prevailing hypotheses for this and other mass extinction events during Earth's history. We will also discuss the effect on evolution/diversification of life following mass extinction events.
I think the subject matter of this lesson is an important educational topic for two reasons. The first is that any discussion of the pattern of evolution, diversification, and extinction of life on Earth over geologic time must necessarily bring up the subject of deep time and the age of our planet. The age of the Earth is not at all a controversial subject among scientists, but recently in the United States, public schools have been pressured to teach "alternative explanations" that have no scientific merit. The second reason is that the subject of mass extinction events ties together the disciplines of geology and biology; it is an important part of teaching and learning science to recognize that scientific disciplines are linked, even though they are usually taught in schools as completely separate fields.
By the end of Lesson 3, you should be able to:
Lesson 3 will take three weeks to complete. 18 Sep - 8 Oct 2019.
The chart below provides an overview of the assignments for Lesson 3. There are two problem sets and two discussions. One of the problem sets is broken into two parts (each part with a different due date).
Requirement | Submitted for grading? | Due date |
---|---|---|
Reading: An introduction to recent debates | No |
24 Sep |
Problem set: Antipodes and Geologic Time, part 1 |
Yes—Submitted to the "Antipode and timescale problem set part 1" assignment in Canvas |
24 Sep (end of week 1) |
Problem set: Antipodes and Geologic Time, part 2 | Yes—Submitted to the "Antipode and timescale problem set part 2" assignment in Canvas | 1 Oct (end of week 2) |
Reading: The K/T extinction event | Yes-Graded discussion in Canvas | participation spanning 25 Sep - 1 Oct (2nd week) |
Reading / Discussion: Exploring a controversial theory—the Permian/Triassic Extinction | Yes-Graded group discussion in Canvas | 1 Oct (end of week 2) |
Problem set: Correlating impacts and extinctions | Yes—Submitted to the "Impact craters problem set" assignment in Canvas | 8 Oct (end of week 3) |
Reading: Recovering from an extinction | No | 8 Oct |
Discussion: Teaching and learning about mass extinctions | Yes—Graded discussion in Canvas | participation spanning 2 - 8 Oct (3rd week) |
If you have any questions, please post them to our Questions? discussion forum (not e-mail). I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
The pattern of evolution, diversification, and extinction of species on Earth is a topic worthy of an entire course (but so are the other topics in Earth 501, as you have no doubt realized at this point). Here we will focus on two major extinction events in geologic history. One of them happened approximately 250 million years ago. It marks the end of the Permian period of the Proterozoic Era and marks the beginning of the Triassic period of the Mesozoic Era. This extinction event was the most catastrophic in geologic history in terms of the number of species that disappeared at this time. The other event we'll study is better known. It happened 65 million years ago, ending the Mesozoic Era and the Cretaceous period, and beginning the Tertiary period of the Cenozoic Era. This is the event that killed the dinosaurs and is often called the "K/T" extinction (K is the abbreviation used for Cretaceous; T is the abbreviation for Tertiary).
These two extinction events have some characteristics in common: extraterrestrial impacts as kill mechanisms have been proposed for both, and in both cases, scientists continue to debate other possibilities as well. In this lesson we will examine different hypotheses proposed for each of the two events, we will examine a database of known impact sites on the planet, and we will try to wrap our minds around the concept of deep geologic time.
Read the following article, available through Canvas:
This article gives a brief overview of some of the most recent debates surrounding the causes of mass extinction events that happened during the Mesozoic Era. Read this now as an introduction to some of the topics we will pursue more deeply as this lesson progresses.
When you read this article, think about the following:
This article does not answer all the questions above, and I have italicized the questions that you may or may not know the answer to depending on your background knowledge of the geologic timescale.
Please post any comments or questions to the Questions? discussion forum, especially if you want more background pertaining to the italicized questions (or other questions). If you have the answers to help out a fellow student, please post!
Geologic mapping involves a certain amount of detective work. Layers of rock preserve a record of the planet's past climate and its biological population. Early versions of the geologic timescale were mostly based on index fossils—these are fossils commonly found in a particular sequence of rock around the world. Finding a certain index fossil meant being able to correlate that rock with other rocks containing that same fossil in other places on Earth. Divisions of time were generally assigned based on the disappearance of index fossils or on changes in rock type at certain points in geologic history. Relative ages of rocks around the world have been cataloged for over a hundred years. However, it has only been since the advent of radiometric dating and paleomagnetic measurements that we have also been able to assign numerical ages to the different divisions.
Here are two versions of the geologic timescale (both are in PDF format):
We do not have perfect preservation of the entire 4.5 billion year history of the planet. Preservation increases towards the present time, as you would expect. Therefore the geologic timescale contains more detailed divisions the closer we get to the present. The first abundant organisms with shells in the fossil record don't even appear until about 542 million years ago, which is a fifth of the way back from the present time. I annoted the second of the two time scales linked above to show where the two extinction events pertinent to this lesson appear in time, and to give you a warning about how the layout isn't to scale.
In the activity below, the whole class will work together to make a representation of the geologic timescale. The way we'll do this uses the concept of antipodes. The antipode is the opposite point of any point on the surface of the Earth so that if you connected the two points with a line through the center of the Earth, that line would be an exact diameter. Mathematically, the antipode of a point whose latitude and longitude are (A, B) equals (-A, B ± 180°).
As an example, the latitude and longitude for State College, PA, is
40.8° N, 77.9° W
Its antipode is 40.8° S, 102.1° E, as shown on a map of where this is located [72].
As you can see, when my children get in the sandbox, they are not digging a hole to China. They are in fact digging a hole to the Southern Indian Ocean off the west coast of Australia.
Here's an animation of an antipode using Eliza's Cherry Skewer Mental Model (Click to download) [73]
Calculate the antipode of your home town. Here is a good link for looking up the latitude and longitude of many locations in the world: Get Latitude and Longitude. [74]
Our planet is approximately 4.55 billion years old. It is a challenge for any human being to comprehend just how long a billion years is. This is one of the reasons that many people have trouble accepting the fact that biological processes such as natural selection can work. How can we try to represent the age of the Earth in a way that people will really understand what a billion years mean?
In this activity, we'll use distance as a proxy for time. Penn State's campus at University Park, PA (in State College) will represent the present time, and PSU's antipode will represent 4.55 billion years ago when the Earth was formed. The great circle distance between PSU and its antipode then represents 4.55 billion years.
Save the Antipode and Timescale Worksheet [75] to your computer. Use that word processing document to record your work.
Record your answers to the following questions on your worksheet:
First, add your data to our class table in Canvas. My data is given as an example. Next, save your worksheet as a Microsoft Word, Macintosh Pages, or PDF file in the following format: Antipode_AccessAccountID_LastName.doc (or .pages or .pdf). For example, Cardinal starting pitcher Adam Wainwright's file would be named Antipode_apw50_wainwright.doc
Upload your Antipode Worksheet to the Antipode and timescale problem set part 1 assignment in Canvas by the end of the first week of this lesson. I will check your work so that you can make any corrections to the class table if you need to before Part 2 is due. Part 2 will be due a week later (the end of the second week of this lesson).
There is a week in between the due dates of part 1 and part 2 of this assignment so I can check part 1 and have you make corrections if necessary. Meanwhile, go on and do the reading assignments/discussions on the following pages, then come back here to finish part 2.
I want you to make a geologic timescale in which the dimension of time is measured consistently at a single scale. The two pdf files of the timescale produced by GSA and the USGS linked from page 3 of this lesson are made the way they are because the authors wanted each named portion of time to be legible, and they wanted to produce something that more or less fit on a page. This is instructive, but it can be misleading because periods of time closer to the present time are given more space. For example, see in the USGS timescale how the Holocene epoch (in which we now live) is given approximately the same amount of space as the late Jurassic. The Holocene is about 11,500 years long and the late Jurassic lasted about 15 million years. So, obviously, we are distorting time in favor of the present. Let's have a little humility and make a model to scale.
It is not as easy to appreciate the vastness of time before anything cool (like life!) began on this planet unless you can see what the timescale looks like when it is drawn to scale, so that's what we'll do next.
Choose a scale that makes sense to you and allows you to fit your timescale on one 8.5" x 11" page. This means you must come up with a scale that will fit 4.55 billion years into something less than eleven inches. Keep in mind that you are not being asked to recreate the standard-issue geologic time scale as they are rarely created with a consistent time scale. HINT: The easiest way to do this will be to draw your timescale on graph paper. You can make your own graph paper online for free and print it out at Incompetech Inc. [76]
You will need to submit your timescale electronically. It is okay to draw your timescale by hand and then scan it. Or, draw your first draft of it by hand and then make an electronic version of it. If you scan something that you have drawn by hand, please check for legibility before submitting it.
Save an electronic version of your timescale as a Microsoft Word, Macintosh Pages or PDF file in the following format:
Timescale_AccessAccountID_LastName.doc (or .pdf or .pages).
For example, Cardinal outfielder Dexter Fowler's file would be named "Timescale_wdf25_fowler.doc"
Upload the electronic version of your timescale (from Part 2) to the Antipode and timescale problem set part 2 assignment in Canvas by the end of the second week of this lesson. NOTE: The timescale (part 2) is due a week later than the antipode worksheet calculations (part 1). This is because you will need the data your classmates provide in Part 1 to complete Part 2. You are probably wondering why I've repeated this fact about four times now. Just to see if you're still reading! No, but, really, I've had somebody get confused about this every time I've taught this class, I swear.
I'll use my general rubric for grading problem sets [47] to grade this activity. I made each half of this problem set worth 50 points so together they'd add up to the usual 100 points.
The mass extinction event that occurred about 65 million years ago brought about an end to the domination of the planet by reptiles and, in so doing, opened up ecological niches within which mammals flourished several million years later (including, happily, human beings!).
History of the impact theory as the cause of the Cretaceous/Tertiary extinction 65 million years ago begins in the Italian town of Gubbio (green arrow in the map below).
The rock sequence preserved in a gorge outside of Gubbio preserves the transition between the Cretaceous and Tertiary periods. The site was visited by geologists conducting paleomagnetic surveys used to make precise dates of geologic horizons. These workers had noticed that while the lower beds of the Cretaceous contained many fossils, the Tertiary beds above the boundary were surprisingly depleted in fossils. There was a thin layer of clay at the boundary, which turned out to have an extremely high concentration of iridium. Iridium does occur in the Earth's crust but the concentration of it in this layer was so high that either the layer must have been deposited over a very long period of time in a way that concentrated the iridium, or else this iridium must have been delivered to Earth all at once from an extraterrestrial source. Precise dates from paleomagnetic data on the beds above and below the clay layer eliminated the possibility that the clay was just a thin feature representing a very long time, so an extraterrestrial source was hypothesized by a team of scientists led by Luis Alvarez and his son Walter Alvarez. We'll read their 1980 paper in Science that outlines their theory. (Alvarez, L., et al., 1980, Extraterrestrial Cause for the Cretaceous-Tertiary Extinction, Science 208, p 1095-1108.) Since this discovery, iridium-rich clay layers have been found at the K/T boundary in rocks all over the world, making the hypothesis for a planet-wide ecological catastrophe caused by an asteroid or comet impact much stronger.
Other evidence of an extraterrestrial impact from the Cretaceous/Tertiary boundary rocks includes tektites, which are glassy spherules of melt ejected from the crater, and shocked quartz, a form of high-pressure quartz only found at other known meteorite impact craters on Earth. The photo below shows tektites from the K/T boundary in Haiti.
Tektites and shocked quartz are found in K/T boundary rocks all over the Earth, but the concentrations of them in rocks around the Gulf of Mexico narrowed the search for the crater to that area. Calculations based on the amount of iridium in the boundary clay gave scientists an estimate of the size of the crater they were looking for. About 15 years ago scientists "found" the Chicxulub crater in the Yucatan peninsula and began a drilling project there to date the crater. I wrote "found" in quotation marks because this crater's existence was known in the oil industry for some time, but the idea that it could be the K/T crater was not thought of until the early 1990s. The 1992 Swisher et al. paper in Science that we will read as part of the reading assignment for this section of this lesson details the age-dating of this crater and other evidence to support Chicxulub as the site of the K/T impact.
Well, what would the fun of that be? The majority of Earth scientists do agree with the Alvarez impact hypothesis because so many lines of evidence support it. However, there are some other fairly catastrophic events that happened on the planet at about 65 Ma, making for an odd coincidence at the very least. For example, the flood basalts of the Deccan Traps in India spewed out at about 65 million years ago. Such extensive volcanism would no doubt have altered the climate seriously. Would that have been enough to cause a mass extinction event? Plenty of geologists think so. It is safe to say a significant number of geologists who work in this field think that there was a sequence of events that led to the end-Cretaceous extinction event, with the asteroid impact being one of them.
My suggestion is to read through the press releases and summaries first because they are intended for a more general audience. Then read/skim the scientific papers, which have been written for experts. Note the different writing styles and differing amounts of technical jargon in the different papers! I have posted some discussion questions you might want to look at first help guide your thinking, so you are ready to discuss.
We will discuss these papers together via a discussion in Canvas. This discussion will take place over the second week of this lesson.
Grading rubric: Please see the rubric for discussions. [1]
Now we're going to begin thinking about a different, even more, catastrophic mass extinction event.
The Permian-Triassic extinction event marked the end of the Paleozoic era and the beginning of the Mesozoic era, which, in turn, was ended by the K/T mass extinction we just finished reading about.
Approximately 250 million years ago, the biggest extinction event in the history of the Earth (in terms of the number of species that disappeared) took place at the end of the Permian period. This event marks the end of the Paleozoic era and the beginning of the Mesozoic era. The rise of reptiles, such as the dinosaurs, is most probably a direct outcome of these species flourishing in the ecological niches left by the end-Permian extinction event. Several theories have been proposed to explain the "Great Dying," but many of these lack global evidence to prove or disprove them, or they do not provide a kill mechanism that is quick enough or extensive enough. One of the difficulties in pinning down a kill mechanism is the dearth of well-preserved outcrops that record this time period in geologic history.
As you read the papers in our next activity that deal with the Permian/Triassic extinction, I want you to keep in mind the major difference between what the scientific community thinks about this extinction, as opposed to the Cretaceous/Tertiary extinction that we read about previously. In the case of the Cretaceous/Tertiary extinction, the impact hypothesis is widely believed and supported and has been for at least a decade. I can verify this because when I teach large-enrollment residential courses for non-science majors here at Penn State, the great majority of the class knows that "a meteor killed the dinosaurs." Usually, none of these same students have even heard of the Permian/Triassic extinction event, despite the fact that whatever happened on Earth at the end of the Permian was quite a bit more catastrophic. At the end of this section of the lesson, we will have a summary discussion so we can compare the story of two different extinction events and discuss why the explanation for one of them is apparently much less controversial than the other.
To see some 250-million-year old rocks, check out this video clip from NOVA [78] in which Neil deGrasse Tyson interviews several geologists who are hunting for answers about the end-Permian extinction out in the field and through computer models.
Lee Kump, Dean of PSU's College of Earth and Mineral Sciences (we filmed this back when he was merely a professor in Penn State's Department of Geosciences), has been studying ancient climates based on the evidence left behind in marine sediments for most of his career. Watch this video below to see him explain some of his hypotheses about the end-Permian mass extinction and to hear more about his research.
In addition, here is a press release about Lee's hydrogen sulfide hypothesis:
Here's the citation for the scientific paper:
In this next activity, we'll concentrate on the relatively new and controversial theory that an asteroid impact caused the Permian/Triassic extinction event. By doing this, I admit that I'm deliberately not spending time on the other theories that have more adherents, such as the theories that Lee talked about in the video on the previous page. First, I want us to talk about impacts, in general, this week. Second, this gives us a way to compare what the state-of-the-art thinking is with respect to extraterrestrial impacts for the Permian/Triassic extinction while the evidence for an impact at the K/T boundary is still fresh in our minds.
Fall 2019: We will not discuss the papers below as part of a graded discussion. Please do skim them because some of the knowledge you get from them will help inform you when you work on the impact craters problem set. I alternate between discussing the K/T and the P/Tr papers each time I teach this class. So the assignment below is just for reading, this time, not discussing.
Then, engage in a class discussion of these hypotheses, which will take place in the "Lesson 3 - Permian/Triassic Extinction" class discussion forum. (See "Submitting your work," below.)
Special note to Group-Work-Haters: I am dividing you up in teams because I have assigned more reading than I think each of you can be expected to process on your own. So, each of you only has to read half of it. Therefore, the job of the group discussion is to clarify your thinking about the papers and also to provide an overview to the other team, through your discussion, of the content of the papers you read.
QUESTIONS:
QUESTIONS:
QUESTIONS:
You will need to participate multiple times during the discussions.
You will be graded on the quality of your participation, both in your team discussion and in the discussion involving the whole class. See the grading rubric [1] for specifics on how this assignment will be graded.
The articles below are press releases that accompanied scientific papers that detail other theories for the end-Permian extinction event. Check them out:
In this activity, you will explore the relationship between known impact events and sudden extinctions on Earth. Want to see a hand sample from an impact crater? Here is a piece of rock from the Vredefort structure in South Africa. The Vredefort is so big that you can't even see across it. The extreme heat of impact created glassy flow bands in the rocks of the crater ring. That's the black part in the photo. It's a little easier to see in the outcrop scale, but it's still cool!
The world map shown in this screencast comes from the impact crater database [86] maintained by the University of New Brunswick's Planetary and Space Science Centre. It shows the locations of known impact crater sites (noted as white dots on the map). In this screencast, I explain the map in more detail [87]. You can also read a transcript of my discussion of the map [88].
As discussed in the screencast, it is instructive to see where craters are and are not found on Earth. For example, craters are conspicuously absent from the oceans, Antarctica, Greenland, the Amazon river basin, central Africa, and Indonesia. Is this real (i.e., is there a scientific reason why asteroids or comets would fall to Earth in certain locations?) or is this an artifact? The reason why craters are not found uniformly over the globe is a result of preferential preservation in some places and also some places on the planet are not as easy to get to, thus potential impact sites have not been explored there.
In the case of the oceans, plate tectonic activity means that the oldest ocean crust dates from the Jurassic, so no impacts older than that could be found there. In addition, oceanic crust is quite thin and not conducive to preserving evidence of an impact.
Frame 1 - Man: I used to think correlation implied causation.
Frame 2 - Man: Then I took a statistics class. Now I don't.
Frame 3 - Woman: Sounds like the class helped. Man: Well, maybe.
For this problem set, create your own document instead of downloading a worksheet.
Your completed problem set should include your timescale, your scatter plot of crater diameter vs. age and answers to the follow-up questions. Save an electronic version of your work in the following format:
Impactcraters_AccessAccountID_LastName.doc (or .yourFileExtension).
For example, Cardinal relief pitcher Tyler Lyons' file would be named "Impactcraters_twl70_lyons.doc"
Upload your document to the Impact craters problem set assignment in Canvas by the end of week 3 of this lesson.
I'll use my to grade this assignment. [47]
How did the mass extinction events of the past change the trajectory of evolution on Earth? How much do human beings impact the future of biodiversity on the planet? In the following reading assignment, we'll explore these topics.
Read the following articles:
As you read these articles, think about these questions:
Feel like sharing your thoughts? Use the Questions? discussion forum to do so!
Let's take some time to reflect on what we've covered in this lesson!
For this activity, I want you to reflect on what we've covered in this lesson and to consider how you might adapt these materials to your own classroom. Since this is a discussion activity, you will need to enter the discussion forum more than once in order to read and respond to others' postings. This discussion is scheduled to run during the last week of this lesson.
You will be graded on the quality of your participation. Please see the rubric for teaching/learning discussions. [1]
Keeping an Eye on Space Rocks [98]: this is an interactive flash movie made by Caltech's JPL about monitoring asteroids and comets close to Earth.
Map Tunneling Tool [99]: this is an interactive web site that helps you locate the antipode of any point on Earth.
Check out these readings if you are interested in other extinction events and/or other impact events. Note: I didn't put any of these readings in our course reserves, but as a PSU student you have access to the PSU libraries, which contain all of these articles. To find out how to get access to them, see Online Students Use of the Library [100].
Have another reading or Web site on these topics that you have found useful? Share it in the Questions? discussion forum!
In this lesson, we briefly covered the construction of the geologic timescale and discussed two of the five great mass extinction events that happened since life began on the planet. These topics are controversial in two important ways. First, scientists still argue about the exact cause of mass extinction events on Earth. Impacts have been invoked for both of the two we discussed but it is interesting how much contention there is, especially for the Permian/Triassic extinction. Second, anytime biology and geology meet, the subject of the age of the Earth and the processes of evolution and natural selection naturally come up. These are not scientifically controversial topics but are often represented that way by nonscientists.
You have reached the end of Lesson 3! Double-check the list of requirements on the Lesson 3 Overview page to make sure you have completed all of the activities listed there.
The map below is a seismic hazard map of the continental United States produced by the USGS. The red bull's eye covering the bootheel of Missouri is the New Madrid Seismic Zone. In this lesson, we will learn about the 1811-12 earthquake sequence in the New Madrid Seismic Zone and discuss the controversy regarding the extent of seismic risk in the central United States today. We will learn how to estimate earthquake recurrence interval using a variety of methods.
Most people on the West Coast of the United States who live near faults or volcanoes (or both) are somewhat familiar with the risks involved with these phenomena. Far fewer East Coast dwellers have felt an earthquake. However, the central U.S. is actually fairly seismically active for a continental interior. This region has experienced large earthquakes in the past and these may happen again. How should residents of this area plan for a potential earthquake hazard? In this lesson, we will explore intraplate seismicity and the New Madrid region in particular. We'll use seismic catalogs to estimate earthquake recurrence interval and we'll discuss the scientific controversy surrounding the potential for large earthquakes in this region.
By the end of Lesson 4 you should be able to:
Lesson 4 will take three weeks to complete. 9 -29 Oct 2019. You will complete reading assignments by the end of the first week. You'll submit the data analyses at the end of the second week. The team reading and discussion assignments will take place over the second week. The whole class paper discussion and the teaching and learning discussion will take place during the third week. The fact sheet paper is due at the end of the third week. See the table below for complete details.
Requirement | Submitted for Grading? | Due Date |
---|---|---|
Reading: "The Mississippi Valley Earthquakes of 1811 and 1812: Intensities, Ground Motion, and Magnitudes" | No | 15 Oct (end of 1st week) |
Reading: "Earthquake hazard in the heart of the homeland" | No | 15 Oct (end of 1st week) |
Reading: series of papers about glacial rebound, failed rift, and the Farallon slab. | No | 15 Oct (end of 1st week) |
Problem set: Earthquake catalog data analyses | Yes - Submitted to "Earthquake catalog problem set" assignment in Canvas | 22 Oct (end of 2nd week) |
Reading/Discussion: "Debating hazard at New Madrid" | Yes - Graded group discussion in Canvas | participation spanning 16 - 22 Oct (2nd week) |
Reading/Discussion: "Debating hazard at New Madrid" | Yes - Graded whole-class discussion in Canvas | participation spanning 23 - 29 Oct (3rd week) |
Paper: NMSZ Fact Sheet paper | Yes - Submitted to the "Fact Sheet Paper" assignment in Canvas | 29 Oct (end of 3rd week) |
Discussion: "Teaching and Learning About Earthquakes" | Yes - graded whole class to the "Teaching and Learning About Earthquakes" discussion forum in Canvas | participation spanning 23 - 29 Oct (3rd week) |
If you have any questions, please post them to our Questions? discussion forum (not e-mail). I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
Please read this article describing the 1811–1812 New Madrid earthquake sequence, then proceed with the rest of the lesson.
Nuttli, O. W. (1973). The Mississippi Valley Earthquakes of 1811 and 1812: Intensities, Ground Motion, and Magnitudes. Bulletin of the Seismological Society of America, 63(1), 227–248.
This paper was written by Otto Nuttli, a seismologist at Saint Louis University. He looked at many historical accounts of the 1811–1812 New Madrid earthquake sequence in order to describe the physics of these events with as much accuracy as possible. This is a technical paper, intended for an audience of other seismologists. I don't expect you to digest every detail of Nuttli's analysis.
Read these sections and their included figures: Abstract, Introduction, Intensity data, Discussion, Reflections.
Skim the following sections: Relations between intensity and ground motion, Magnitudes and ground motion of the 1811–1812 earthquakes, Appendix.
When you read this article try to answer or at least think about the following:What other questions do you have after reading this article? Post to the Questions discussion.
This is a slick USGS-produced poster with an overview of historical earthquakes in the New Madrid Seismic Zone. For best viewing, you will want to download the file from the USGS so you can zoom in and read the text.
Before you proceed, please complete the following reading assignment. Then, in the next part of the lesson, we will discuss the scientific background necessary to appreciate why there is a scientific controversy over the level of seismic hazard in the central USA.
Gomberg, J., & Schweig, E. (2002). Earthquake hazard in the heart of the homeland [104]. Fact Sheet - U. S. Geological Survey, 4.
This reading is a fact sheet published by the USGS [105]in 2002 that addresses the level of present-day earthquake hazard in the central USA. As you read, think about the following:
If you have questions or comments, especially pertaining to the questions I have posed above, please post to the Questions discussion. There is nothing to submit for this assignment, but you will want to read this fact sheet thoughtfully because your final assignment for this lesson will be to rewrite and update it with new data.
The theory of plate tectonics makes two mathematical assumptions:
In fact, the Earth is not a perfect sphere; it bulges at the equator a bit. The second assumption is also not quite true. If plates were perfectly rigid in their interiors, then earthquakes could only happen at plate boundaries. Nearly all earthquakes (98%+) do happen at the plate boundaries, but there are some anomalous events, called intraplate earthquakes, that happen far from the boundaries.
The map below shows earthquake locations around the world for a six-month period. Compare it to the plate boundary map below it and you will see that earthquakes roughly define the plate boundaries. Focus on the North American plate. It is bounded on the west at the edge of the continent and on the east by the Mid-Atlantic Ridge. The East Coast and the central United States are quite far away from any plate boundaries, yet you may notice a fair amount of seismicity locating there. Seismologists are interested in these earthquakes because plate tectonics doesn't explain their existence very well.
Why do earthquakes happen in the center of the continent? Different scientists have different favorite explanations. Below are three scientific papers that each present a different hypothesis to explain why the New Madrid Seismic Zone is seismically active. I have also included three companion articles written for the popular press. For this activity, you will read the articles. You don't need to turn anything in, but you will want to internalize the main arguments of each hypothesis in order to include this information in your fact sheet paper (the culminating assignment for this lesson).
Read each of the following popular press articles and scientific papers. Keep track of any points made in the scientific papers that you don't understand so you can ask about them. There's no formal graded discussion of these papers, but feel free to post comments/questions in the Questions discussion forum. My suggestion is to read the companion popular press article in each set first so that you are already familiar with the main points of the hypothesis before tackling the scientific paper.
In the next part of this lesson, you will analyze seismic data and learn how to estimate earthquake recurrence times with seismicity catalogs. Then you'll read some scientific articles that detail the other ways recurrence intervals can be estimated. You will have to synthesize the uncertainties and limitations inherent with each method in order to get the complete picture of how earthquake risk is determined.
Here is an important observation about earthquake populations worldwide: earthquakes of a given magnitude happen about 10 times as frequently as those one magnitude unit larger.
Magnitude | Average Annually | How we know |
---|---|---|
8 and higher | 1 | observations since 1900 |
7.0-7.9 | 15 | observations since 1900 |
6.0-6.9 | 134 | observations since 1990 |
5.0-5.9 | 1319 | observations since 1990 |
4.0-4.9 | 13,000 | estimated |
3.0-3.9 | 130,000 | estimated |
2.0-2.9 | 1,300,000 | estimated |
Annual earthquake population statistics compiled by the USGS [109].
Earthquake populations approximately follow this relationship:
log N = a - bM.
This is a power-law equation in which N is the number of earthquakes whose magnitude exceeds M and a and b are constants. For the majority of earthquake catalogs, the constant b is approximately equal to 1. When b≈ 1, this equation describes a line whose slope is about -1.
Seismologists can test the validity of the equation above using catalogs of earthquakes to make "frequency-magnitude diagrams." These diagrams show how many earthquakes of a given magnitude there are in a population of earthquakes.
A frequency-magnitude plot with real data! [110]You can also read a transcript of my discussion of a frequency-magnitude diagram [111] of a year's worth of earthquakes from around the world.
Now observe the plot below. For two separate catalogs of earthquakes that occurred in the New Madrid region, magnitude is plotted vs. the mean annual occurrence of earthquakes greater than or equal to a given magnitude. This plot is only different from the example plot above in that the N values on the y-axis have been normalized to one year. This is so two catalogs that span different lengths of time can be compared directly.
Both of the curves in the plot above deviate from a straight line relationship log N = a - bM at small magnitudes. For the Nuttli Catalog, the line has a slope of about -1 at magnitudes greater than 3.5 and for the NMSZ catalog, the line has a slope of about -1 for approximately magnitude 1.5 and greater. Doesn't it look like in the Nuttli Catalog, there is the same number of magnitude 2 earthquakes every year as there are magnitude 3 earthquakes? But didn't we say that there should be ten times more magnitude 2's? What's going on?
Furthermore, how come there aren't any big earthquakes in this plot? The New Madrid Seismic Zone (NMSZ) catalog peters out at about magnitude 5 and the Nuttli Catalog doesn't have anything much over magnitude 6. But we know there have been big earthquakes in this region in the past, (or else why argue about seismic risk here), so where are they?
The answer to both of these problems is simply that any catalog of earthquakes is limited in two ways (pencast graphical explanation of observation limits [112]). The first way is that not every piece of the Earth has a seismometer sitting on it, therefore there will be some small earthquakes that don't get recorded, even though they happened. For most catalogs, some standard is applied with regard to how many seismometers have to record an earthquake in order to include it in the catalog. This is for quality control reasons. It is hard to locate an earthquake and calculate its origin time within acceptable error limits if not enough stations recorded it. Therefore, the farther apart the seismometers are, the fewer small earthquakes will end up being included in the catalog. For the Nuttli Catalog, we can say that the catalog is incomplete below the threshold of M ≈ 3.5 because that is where the slope of the line (or the "b-value") begins to deviate from -1. The threshold for the NMSZ catalog is lower. Why do you think this is?
The second way a catalog is limited is that it is finite in time. Let's say for a given region, magnitude 8 earthquakes happen once every 1,000 years or so. If your catalog only spans 10 years, how likely are you to have a magnitude 8 in your catalog? For that matter, how likely are you to have a magnitude 7 in your catalog? How many magnitude 6's can you expect in 10 years? In the plot above, the time ranges for both catalogs are listed on the plot. Why does the NMSZ catalog have a lower maximum magnitude than the Nuttli Catalog?
In order to assess seismic risk, we want to know how often a large earthquake happens in this region. How do we do that if our seismometers haven't ever recorded a big earthquake? We have to extrapolate using the data that we do have. Extrapolation is a tricky business because small uncertainties turn into huge uncertainties the farther away you get from what you've actually measured. For a catalog of seismicity, we rely on the assumption that the relationship log N = a - bM holds true overall magnitudes and times. We then extend our catalog data into the realm of the unknown and predict how often large magnitude earthquakes are expected. In the plot above from Newman et al., 1999, they use dashed lines to show their extrapolations. How often do they predict a magnitude 7 will happen in the NMSZ? What about a magnitude 8? What uncertainties do they associate with these predictions?
How to extrapolate seismic catalog data in order to calculate a recurrence interval! [113]You can also read a transcript of my explanation of extrapolating catalog data [114] to calculate a recurrence interval.
For the following problem set, you will work with the seismicity catalog maintained by the University of Memphis for the New Madrid region in order to make your own frequency-magnitude diagrams and calculate a recurrence interval for a large earthquake at the NMSZ. You will also compare NMSZ data to seismicity catalogs for southern California and the world. The point of this comparison is that you will see that the overall shape of a frequency-magnitude diagram is scale-independent. It doesn't matter how big your regional area is, or how many years your catalog covers, the same basic -1 slope coupled to two sections on either end that deviate from -1 will always be there. What changes is the place on the diagram where the deviation occurs? Pay attention to this when you make your different plots.
Go to the New Madrid Earthquake Catalog Search. [115]
Once you get there, follow my directions to make a 1-year catalog of NMSZ seismicity:
Here is video above as plain text [116]
Create a word processing document (Microsoft Word, Macintosh Pages, Google Docs, or PDF) to record your work for this problem set.
On the worksheet, paste in your map of the 1-year catalog you made. Then answer the following questions:
1.1 How many earthquakes are in your catalog?
1.2 What is the largest magnitude earthquake in your catalog? How many earthquakes are there of this magnitude in your catalog?
1.3 What's the smallest magnitude earthquake in your catalog? How many earthquakes are there of this magnitude in your catalog?
1.4 Describe your map in a few sentences. (What part of the country is it? Are the earthquakes sprinkled randomly about or do they cluster in patterns? If the latter, describe what the patterns look like.)
Double-Check! Your worksheet should now have a map and answers to the Part 1 questions. If it does, you are ready to take on Part 2.
Make three different frequency-magnitude plots using the New Madrid Earthquake Catalog data: The first plot will use the one-year catalog you made in Part 1 of the problem set. In the second plot, you will add curves that correspond to a 10-year, 20-year, and 30-year catalog. The third plot will depict the same data as in the second plot, except that you will normalize all the catalogs to one year. Specific directions follow:
For this plot, all you need are the magnitudes, which are in column 7 of your plain text catalog file. Post to Questions if you need help isolating that column. My recommendation is to create a new file in whatever plotting/spreadsheet program you like and then you will type your counting statistics into this new file. In your new file, you want to create the values that will be on the x-axis of your plot. They will be magnitudes from your catalog's lowest to your catalog's highest in 0.1-unit bins. To create the values that will be on the y-axis of your plot, count how many earthquakes in your catalog are equal to or greater than each value of magnitude. These are your y-values: cumulative frequency. It's easier to count if you sort your magnitudes first, which is fine to do because we do not care what order they are in for this plot.
Then plot cumulative frequency vs. magnitude.
Use a logarithmic (base 10) scale for the y-axis or take the log of your cumulative frequency data and plot that on a linear axis. You can use a linear x-axis because magnitude is already a power of 10. [Is this confusing? Post to the Questions forum if you need help.]
If you are having trouble, see my example plot [117] for a one-year catalog of earthquakes in the New Madrid Seismic Zone (NMSZ). I used the year 1975, so this plot will not be precisely the same as yours, but it should look pretty close.
Start with the plot you just made.
Go back to the New Madrid Earthquake Catalog and make a catalog for a ten-year time period (you can choose any ten-year period). Overlay the frequency-magnitude curve for this ten-year catalog onto the curve you made in the first plot.
Repeat for a twenty-year period.
Repeat for a thirty-year period.
You should now have one plot with four curves on it.
Make sure each curve is distinguishable (by color or linestyle) and labeled.
Start with the original one-year catalog plot you made.
Overlay the curve for the ten-year catalog, but normalize the curve to one year. This is accomplished by dividing each of your y-values by 10.
Repeat for the twenty-year catalog (divide y-values by 20)
Repeat for the thirty-year catalog (divide y-values by 30)
You should now have one plot with four curves on it.
Use the same distinguishing color or linestyle for each curve as you did in your second plot.
Dust off your worksheet from Part 1. On the worksheet, first paste your three plots into the worksheet, then answer the following questions:
2.1 Look at the first frequency-magnitude plot you made of the one-year catalog. Approximately what is the lower magnitude threshold for this catalog? (Follow your data from right to left and tell me at about what magnitude the line flattens out to having zero slope?)
2.2 Now look at the other two plots you made. Do the other curves show a significantly different lower magnitude threshold? From this observation, what do you conclude about the relationship between catalog timespan and lower magnitude sensitivity?
2.3 Look at the second plot you made. Describe the differences and similarities among the four curves in a few sentences. For example, are the curves of the same shape? Where are the x- and y-intercepts relative to each other? What makes the y-intercepts different? What causes the x-intercepts to be different?
2.4 Look at the second plot you made. Imagine having a catalog that spans 100 years. Using the four curves you made as a guide, extrapolate where the x and y intercepts would each be for a 100-year catalog. What is the largest earthquake you would expect for a 100-year catalog?
2.5 Look at the third plot you made. Extrapolate your curves and predict how often a magnitude 7 earthquake will occur in this region and how often a magnitude 8 will occur in this region. I want you to make a reasonable eyeball-fit. I am not asking you to calculate a best fit line. **If the answer is a fraction less than one, then you can take the reciprocal and predict how many years go by in between magnitude 7's and in between magnitude 8's.
2.6 You have just used frequency-magnitude relationships to predict a recurrence interval for a large New Madrid earthquake. Cool! What are the sources of uncertainty in the prediction you made in problem 2.5? (One way to realize just how much uncertainty there is in an extrapolation like this one is to try making several slightly different fits to the data that all look "pretty good" to you and see how different your final answers end up being.)
Double-Check! Now your worksheet should have the map and answers from Part 1 as well as three plots and answers for Part 2. Hang on to the worksheet and use it for Part 3.
Use the Southern California Earthquake Center Web site to make a seismicity catalog, map, and frequency-magnitude plot.
Go to the Southern California Earthquake Data Center's Earthquake Catalog Search [118] page.
Or follow along as a plain text [119] to make a one-year catalog of seismicity.
Take a screenshot of the google map you made and paste it into your problem set.
Make a frequency-magnitude plot for the events in this catalog:
Use the United States Geologic Survey catalog to make a one-year global seismicity catalog, and add this data to your frequency-magnitude plot that has Southern Cal and the NMSZ on it.
Go to the USGS Earthquake Search [120] page.
Once you are there, follow my plain text directions for making a one-year global catalog [121].
Add to your plot!
3.1 How many earthquakes are in your one-year catalog for Southern California? What is the largest magnitude earthquake in the catalog? How many earthquakes are there of this magnitude?
3.2 How many earthquakes are in your one-year catalog for the world? Are you surprised by this number? What is the largest magnitude earthquake in the world catalog? How many earthquakes are there of this magnitude? Remember that we cut off our global catalog at a minimum magnitude of 4.5. Look at your frequency-magnitude curve for the global catalog and estimate how many earthquakes there would be in your catalog if we had gone all the way down to zero for the minimum magnitude. Translate that into an approximate number of earthquakes per day in the world. (wow, huh!)
3.3 Look at your map of Southern Californian earthquakes. Describe it in a few sentences (i.e., Where are the earthquakes? Do they cluster in space? Beware of artificial clustering that we induced by where we set our search parameters.).
3.4 Look at the map of one year's worth of earthquakes made by the Advanced National Seismic System [122] and describe it in a few sentences. How do the earthquakes cluster?
3.5 Compare the frequency-magnitude curves for New Madrid and Southern California. Which one of the two catalogs is has its lower magnitude threshold at a smaller magnitude? Which region is more seismically active in terms of the number of earthquakes? Which region is more seismically active in terms of earthquake magnitude?
3.6 Compare all three frequency-magnitude curves. How often does a big earthquake (M > 7 or so) happen in the global catalog vs. in the two regional catalogs? Why is this?
Now your worksheet should contain the map and answers from Part 1, the three plots and answers from Part 2, and the map, plot, and answers from Part 3. And the green grass grows all around and the green grass grows all around. Haha, but seriously, save your file in the following format:
L4_catalog_AccessAccountID_LastName.doc (or .yourExtension)
For example, Cardinal pitcher Michael Wacha's file would be named "L4_catalog_mjw52_wacha.doc"
Create one document that contains:
Once you've finished this whole problem set, submit it to the "Earthquake catalog problem set" assignment in Canvas by the due date listed on the table on the first page of this lesson.
I will use my general rubric for grading problem sets [47] to grade this activity.
The New Madrid Seismic Zone presents a difficult problem. We know that large earthquakes have happened in the past. If earthquakes of that magnitude happened today, the damage and recovery would be difficult. Here is the problem: how big were those historical earthquakes actually? How likely are they to happen again? How should the cost of retrofitting be weighed against the predicted cost of a large earthquake? Scientists and policymakers have different training. Scientists are trained to assess the recurrence interval and estimate the ground motion of hypothetical events, while policymakers are trained to assess normative problems (i.e. given a seismic risk at some level, what should we do about it?)
In the data analyses you just completed, you became familiar with earthquake catalogs, including their strengths and limitations. You practiced looking at frequency-magnitude diagrams and you used this data to estimate the recurrence interval for earthquakes of various sizes. In fact, seismological data is just one of the tools scientists use to estimate earthquake recurrence interval. In the reading activity on the next page, you will break up into groups to investigate other methods of studying the NMSZ.
Over the past ten or fifteen years, global positioning system satellite data has become an invaluable tool for measuring plate motion and strain accumulation across faults. This data is gathered by installing geodetic markers in the ground. Scientists then use GPS receivers at the sites of the markers to find out their exact locations from satellites. Over time, the position of some markers may shift relative to each other; for example, markers on opposite sides of a fault may move closer together or further apart or be offset laterally as the years go by. This motion can be used to infer the strain rate in the crust. In the case of the New Madrid Seismic Zone, the faults are buried, so GPS data can help to find out exactly where the faults are and to determine the direction and extent of motion along them.
After several years of repeated measurements, the motion of the markers over the measurement time period is assessed. At active plate boundaries, such as along the San Andreas Fault on the West Coast of the United States, geodetic surveys have been used in concert with detailed records of seismicity to estimate stress buildup on faults and to predict seismic hazard. For example, a suite of geodetic markers may be placed around a fault of interest. After many measurements, the motion of the markers relative to each other can confirm the sense of motion on the fault, how fast the plates on either side of the fault are moving, and whether the fault itself is creeping or locked.
There have been several GPS campaigns over the last decade whose purpose has been to discover how much strain is building up at the New Madrid Seismic Zone. This work has been tricky because the faults involved are not well mapped, so the decision about where to place the markers hasn't been straightforward. The debate is still ongoing concerning whether the strain rates are high, thus posing a great seismic risk, or whether the strain rates are low, thus posing a lesser seismic risk to the area.
The map below shows current GPS stations operating in the USA.
Some faults can be excavated and mapped geologically in order to find out about the recurrence interval for large earthquakes. This sort of work is often done by digging a big trench with a backhoe and then trying to date any large offsets that are found. This technique is useful because the largest possible earthquakes of even quite active faults usually happen several hundred years apart. (Recall the ballpark range of recurrence intervals you estimated in your data analysis exercise.) We simply don’t have seismicity records that go back that far in this country. Dates for prehistoric earthquakes can be estimated by using the dates of the sediments that have been interrupted by an earthquake or some bit of organic material, such as charcoal, in an adjacent layer that can be dated. In the New Madrid Seismic Zone, stream offsets and evidence of liquefaction (sand blows and dikes) caused by strong shaking are also clues to past earthquakes. Paleoseismologists use all these clues to try to put together a timeline of recurrence interval and the approximate earthquake magnitude for a particular fault. These data can be linked with seismicity catalogs and geodetic surveys to get a fuller picture of seismic hazard.
To see excavation and mapping in action, check out this short video from Teachers' Domain and NOVA Online about the work of Kerry Sieh [127], a paleoseismologist at The Earth Observatory of Singapore (He was a prof at Caltech when they made this video).
The Earth produces heat from the decay of radioactive elements in its interior. This heat drives mantle convection and therefore the movement of tectonic plates. Heat flow is routinely measured in boreholes around the planet. These measurements are compiled to produce a map of heat flow for the Earth's surface. Some degree of estimation and smoothing must be applied to the measurements because the boreholes are not evenly spaced and some are on continents while other measurements are taken in oceanic crust. The map below shows global heat flow.
This map shows color-coded contours of the global distribution of heat flow at the surface of the Earth's crust. Major plate boundaries and continent outlines are also shown. The fundamental data embodied in this map are the more than 24,000 field measurements in both continental and oceanic terrains, supplemented by estimates of the heat flow in the unsurveyed regions. The estimates are based on empirically determined characteristic values for the heat flux in various geological and tectonic settings. Observations of the oceanic heat flux have been corrected for heat loss by hydrothermal circulation through the oceanic crust. The global data set so assembled was then subjected to a spherical harmonic analysis. The map is a representation of the heat flow to spherical harmonic degree and order 12.
What does this have to do with the New Madrid Seismic Zone? By looking at the map above, you can see that the amount of heat flowing out of the Earth is not uniform over the surface of the planet. Some areas have much higher heat flow than others and these areas are usually associated with tectonic activity such as volcanism and plate boundaries. For example, the boundaries of the North American plate, the Mid-Atlantic Ridge and the San Andreas fault system, both show up as "warm" places on this map. Heat flow measurements have been made in the New Madrid Seismic Zone to see whether this is a high heat flow area compared to what would be expected for the interior of a continent. (Conventional geophysical wisdom holds that the interior of continents should be old, cold, and stable.) If heat flow is higher than expected, this would be evidence for why earthquakes happen in this area. This remains a point of scientific contention. Past surveys concluded that heat flow was high in the NMSZ, but the most recent studies disagree with those earlier findings.
The map below comes from the Global Heat Flow Database [130], at the University of North Dakota. They have heat flow maps and data files for all different parts of the world. This particular map shows borehole data for the United States. Warm colors denote higher heat flow than cool colors (see the legend, which shows milliwatts per meter squared values color-coded). Notice that this map looks different than the global map above. It looks different because it shows exact borehole measurements as opposed to smoothed values that have been interpolated over the whole map. Where is the heat flow highest? Where is it lowest? Compare this map with the map above to see whether they are consistent for the US.
In this assignment, you will break up into teams to read and discuss the papers designated for you. After this, the class will regroup as a whole and discuss all the papers.
I will divide the class into 3 teams.
Each team should begin by reading their assigned readings and consider the related discussion questions as described below. Papers are linked from your team's discussion board in Canvas.
Team 1: GPS measurements
Members of Team 1 should read thoroughly the seven letters, responses, and summaries listed below to get a sense of the debate about GPS measurements of the NMSZ. Then read/skim the two scientific papers to flesh out your understanding of the studies involved in this debate.
Team 2: Paleoseismology
From the list below, members of Team 2 should browse Martitia Tuttle's Web site and read the Geotimes and Economist articles to get a sense of the current state of the art in paleoseismology at New Madrid. The short article from The Economist discusses a pretty new and novel way of approaching paleoseismology. Then skim the two scientific papers by Roger Saucier to flesh out your understanding of the studies involved.
Team 3: Heat flow measurements
Members of Team 3 should read thoroughly the two summaries and news articles listed below to get a sense of the debate about heat flow measurements of the NMSZ. Then read the two scientific papers to flesh out your understanding of the studies involved in this debate.
Midcontinent heat may explain great quakes [137]. (1993).Science News, 143(22), 342.
Upon completion of the reading, you are to engage in a discussion of the readings, first within your team and then with the rest of the class. The team discussion component of this activity will take place over a few days and will require you to participate multiple times over that period. Likewise, the class discussion will then take place over the subsequent few days.
Team discussions:
Class discussion:
Once you have discussed these topics within your team, we will regroup to engage in a discussion with the entire class. This class discussion will take place in a separate discussion forum titled "Debating Hazard at New Madrid - Class Discussion."
You will be graded on the quality of your participation. Please see the rubric for teaching/learning discussions. [1]
For this activity, you will rewrite the USGS fact sheet you read earlier in the lesson, updating it with the research progress that has been made since it was published.
Rewrite USGS Fact Sheet FS-131-02, Earthquake Hazard in the Heart of the Homeland [102], highlighting the research progress that has been made since 2002, when this fact sheet was published. Specifically, your mission, should you choose to accept it, is to do a better job than the USGS did themselves when they updated FS-131-02 in late 2009 with this new fact sheet, FS09-3071, Earthquake Hazard in the New Madrid Seismic Zone Remains a Concern [139]. (Maybe they were worried that alums of this course would steal their jobs).
I expect your fact sheet to be well organized and coherent, with none or few grammatical and spelling errors. It needs to be completely rewritten in your own words. All references to the scientific work of others (this includes summaries of their results and/or any borrowed figures) must be properly cited and a bibliography must be included.
This fact sheet is meant to be explanatory and persuasive. It should be written for a hypothetical general audience (i.e., non-scientists). It should be clear to me that you understand the significance of the results of all the scientific studies you refer to in your paper (including your own). See grading rubric below for more details.
The successful paper should meet the following criteria (points out of 100 total in parentheses):
It is fine to use figures, graphics, and data from other sources as long as you cite them appropriately and include them in the bibliography. It is also fine (and encouraged!) to organize the fact sheet differently than the original or to emphasize different areas of research than the original. Be creative!
The following resources might be helpful to you in your task. (You are in no way limited to these, of course. You may use whatever appropriate sources you want to.) References that are not clickable are linked from the Canvas module for this lesson.
Save your paper as either a Microsoft Word or PDF file in the following format: L4_paper_AccessAccountID_LastName.doc (or .pdf) For example, Cardinal relief pitcher Trevor Rosenthal's file would be named "L4_paper_tjr26_rosenthal.doc"
Upload your paper to the Fact Sheet Paper assignment in Canvas by the due date indicated in the table on page 1 of this lesson.
Let's take some time to reflect on what we've covered in this lesson!
For this activity, I want you to reflect on what we've covered in this lesson and to consider how you might adapt these materials to your own classroom. Since this is a discussion activity, you will need to enter the discussion forum more than once in order to read and respond to others' postings.
You will be graded on the quality of your participation. Please see the rubric for teaching/learning discussions. [1]
Nature Publishing Group [149]
Newman et al. (1999) Slow Deformation and Lower Seismic Hazard at the New Madrid Seismic Zone, Science, 284, 619–621.
Boyd, O.S., R. Smalley, Jr., and Y. Zheng (2015), Crustal deformation in the New Madrid seismic zone and the role of postseismic processes, J. Geophys. Res. Solid Earth, 120, 5782–5803, doi:10.1002/2015JB012049.
The New Madrid Seismic Zone is enigmatic because it has produced large earthquakes in the past, but its future is unclear. Deciding how to plan for the seismic hazard is not easy and this is compounded by the fact that large sums of money and large amounts of government intervention are involved. I want to stress that just because scientists do not agree, this does not mean that science doesn't work! The problem is that scientists and policy-makers have different training. What do you think forms the greatest barrier between science and public policy?
You have finished Lesson 4. Double-check the list of requirements on the Lesson 4 Overview page to make sure you have completed all of the activities listed there before beginning the next lesson.
If you have anything you'd like to comment on or add to, the lesson materials, feel free to post your thoughts in the Teaching/Learning discussion! It's one of your final assignments in this lesson anyway. For example, what did you have the most trouble with in this lesson? Was there anything useful here that you'd like to try in your own classroom? Is seismic hazard a topic you and your students are interested in? Are there many well-known seismically active faults where you live? (Even if you don't think so, you could always try playing around with the seismic catalog search features we used in this lesson to find out.)
In this lesson, we will investigate a combination of several different datasets and models in order to analyze the extent to which global climate is affected by human activity. We will discuss the short and long term consequences of global warming and try to quantify the uncertainties inherent in scientific measurements.
Lesson 5 will take us two weeks to complete. The topic here (also worthy of a course in itself) is recent climate change. My plan is to spend week one studying the data and observations related to climate change and then spend the second week thinking about models, theories, predictions, and discourse (scientific and political) based on those data and observations. I chose to break up this lesson in this manner because I think some of the misunderstandings about what is, and is not, known about recent climate change comes from a general public that is not literate when it comes to the task of distinguishing observations from models, and from scientists who use words such as "belief" and "uncertainty" without realizing that the general public interprets those words differently than scientists do.
The topics in lesson 5 are covered in a more rigorous semester-long fashion in Meteo 469, so if climate science interests you, that's a good course to take.
By the end of Lesson 5, you should be able to:
The table below provides an overview of the requirements for Lesson 5. Lesson 5 will take us two weeks to complete. 30 Oct - 12 Nov 2019
Requirement | Submitted for Grading? | Due Date |
---|---|---|
Reading: "The Curse of Akkad" | No |
5 Nov (end of1st week) |
Reading/Discussion: "Rapid Wastage of Alaska Glaciers and Their Contribution to Rising Sea Level" | Yes—posted to the "Alaskan Glaciers" discussion forum in Canvas | participation spanning 30 Oct - 5 Nov (1st week) |
Problem set: Plot your own climate data | Yes—Submit this assignment to the "Keeling curve problem set" dropbox in Canvas | 5 Nov (end of 1st week) |
Reading: "The Real Holes in Climate Science", "Fixing the communications failure", "Climate Confusion Among US Teachers", "Climate Change: Past as guide to the future," and "Global-scale temperature patterns and climate forcing over the past six centuries" | No---but necessary for the Teaching/Learning discussion |
12 Nov (end of the second week) |
Problem set: Write your own climate lesson using the JCM | Yes—Submit to the "Java Climate Model" dropbox in Canvas | 12 Nov (end of the second week) |
Discussion: "Teaching and learning about climate change" | Yes—posted to the "Teaching and Learning About Climate Change" discussion forum in Canvas | participation spanning 6 - 12 Nov (second week) |
If you have any questions, please post them to our Questions? discussion forum (not e-mail). I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
As we begin Lesson 5, first read the following article, located through Library Reserves:
This article appeared in The New Yorker in 2005 and was written for a general audience. I think it gives a good introduction to the topic of climate change for two reasons. Firstly, it gives a brief overview of how global climate models work and what kinds of measurements climate scientists make. Secondly, the interesting link between catastrophic climate change and the fall of ancient civilizations is explored. This is a topic that all intelligent and scientifically literate people of the world today would do well to think about.
As you read, contemplate the following questions:
If one wants to make the case for global warming, why not start with the obvious and find out what recent temperature measurements have to say? The plot below shows temperature measurements for the ocean surface, the lower atmosphere, and the land averaged together. The x-axis is time, from the year 1850 until the year 2007. The left-hand y-axis is the global temperature anomaly in degrees Celsius. This anomaly is taken relative to the average of the span from 1961 to 1990. We can see that the land, sea, and air were colder before 1961–1990, and they are all warmer now and have been increasing steadily and rapidly over the last few decades. Note that the rate of increase is getting faster, as the fits to the data points for shorter timescales are steeper (compare the slope of the red line that fits the data over the last 150 years to the slope of the yellow line that fits the data for the last 25 years).
Annual global mean observed temperatures (black dots) along with simple fits to the data. The left-hand axis shows anomalies relative to the 1961 to 1990 average and the right-hand axis shows the estimated actual temperature (°C). Linear trend fits to the last 25 (yellow), 50 (orange), 100 (purple), and 150 years (red) are shown, and correspond to 1981 to 2005, 1956 to 2005, 1906 to 2005, and 1856 to 2005, respectively. Note that for shorter recent periods, the slope is greater, indicating accelerated warming. The blue curve is a smoothed depiction to capture the decadal variations. To give an idea of whether there are meaningful, decadal 5 to 95% (light blue) error ranges about that line are given (accordingly, annual values do exceed those limits). Results from climate models driven by estimated radiative forcings for the 20th century suggest that there was little change prior to about 1915 and that a substantial fraction of the early 20th-century change was contributed by naturally occurring influences including solar radiation changes, volcanism, and natural variability. From about 1940 to 1970, the increasing industrialization following World War II increased pollution in the Northern Hemisphere, contributing to cooling, and increases in carbon dioxide and other greenhouse gases dominate the observed warming after the mid-1970s.
Remember that the overall annual average temperature of something huge, like the ocean, or the land surface, is not directly relevant to daily weather patterns. Therefore, even what looks like a modest increase of less than a whole degree Celsius over twenty years can have a large impact on world climate.
Recall from our discussion of heat flow in the New Madrid lesson that the Earth is a constant emitter of heat, both from the original heat of formation of the planet and from the decay of radioactive elements. The geothermal gradient describes the rate of increase of temperature of the interior of the planet as a function of depth and can be inferred from theoretical geochemical calculations, as well as seismic wave speed. The average geothermal gradient of the Earth is about 15°–25° C per km. This depends on the tectonic setting, as we saw in the New Madrid lesson.
Instrumented boreholes are used to measure heat flow at the surface (upper few kilometers or so) and they generally show a negative deviation from the geothermal gradient in the upper hundred meters of the subsurface because heat loss is greatest where the temperature difference is greatest—at the surface. This leads to a temperature vs. depth relationship that should look like the red lines on the figure below. In fact, boreholes are increasingly showing evidence of recent warming at the surface of the Earth. In the figure below the actual temperature measurements are the black dots and the red lines are just a sketch. The black dots show a positive deviation from the expected geothermal gradient. The observed profiles indicate warming, and the depth of the bend indicates warming in the last 100 years.
Temperature measurements (black dots) and a sketch of the expected geothermal temperature profile (red curves) in three boreholes in eastern Canada. The curvature in the upper parts of the profiles is a response, at least in part, to temperature changes at the surface. The linear increase of temperature with depth in the deeper sections of the holes is the undisturbed geothermal gradient.
One of the direct consequences of a climate that is becoming warmer on average is that global repositories of ice are beginning to melt. Measuring the amount of melting takes time and requires repeated observations because ice caps and glaciers have natural seasonal cycles (more ice in the winter, less ice in the summer). Below is a schematic figure showing data collected for forty years in the Arctic. Polar sea ice thinned by an average of over a meter during that time!
A survey of over 60 glaciers in Alaska has shown an alarming trend. On average, glaciers have been thinning from 1950 onwards. The rate of thinning has rapidly increased during the last ten years or so. Be careful to note the difference between discussing the amount of thinning and the rate of thinning. The amount of thinning is found by measuring the thickness of ice at two different times and subtracting. The rate of thinning refers to how fast the ice is getting thinner. Mathematically, the rate of thinning is the derivative of the amount of thinning, just like velocity is the derivative of displacement if you want to think of it in terms of simple motion. So, even if the rate of thinning was a constant number, say 10 centimeters per year, the amount of thinning would still be increasing every year (by 10 cm). The two figures below show a map of the glaciers from Arendt et al.'s 2002 study of Alaskan glaciers and a bar graph that denotes the rate of thinning for two different time periods of each glacier in the study. The observation of an increase in the rate of thinning is like an acceleration, to continue the analogy to simple motion. It means that glaciers in the past 10 years have been thinning even faster than they used to be.
What happens when ice melts? That's easy: it turns into water. Where does the water go? Eventually, it finds its way into the ocean. In the case of Arctic sea ice, the contribution of melt to global sea level is negligible. That's because this ice is already sitting in the water. The density of ice is less than that of water, but not by a whole lot. On the other hand, when Alaskan glaciers melt, this extra water does increase sea level around the world because the ice had been trapped on the land before. The activity below demonstrates this principle in a simple way.
Sridhar Anandakrishnan, a professor in Penn State's Department of Geosciences, conducts field geophysical experiments on glaciers in Antarctica. Watch the video below to find out more about how his work on glacier dynamics relates to other studies of recent climate change.
The volumes discussed in studies like these (for example, the amount of ice loss, the amount of meltwater produced, etc.) are given in cubic kilometers. Do you have any sense about how much water is in a cubic kilometer? Here's a little estimation that puts this into perspective
The contribution of land glacier melting to global sea level rise has been explored in a recent study of Alaskan glaciers. In this study, airborne laser altimetry was used to determine the mass and thickness of over fifty glaciers. This method is a huge improvement over previous studies that have used complicated and imprecise mass-balance calculations to estimate the rate of glacial melting. The results of this new study show that Alaskan glaciers contribute more meltwater than was previously thought and are losing mass faster than was previously thought. When you read these papers, think about how the results of this study will be incorporated into global climate models.
Then, read a paper that is about climate modeling in which researchers construct a model that does a better job of fitting the sea level and temperatures of the past than has previously been accomplished. The key was adding in warming ocean currents, a warm atmosphere, and a chain reaction of collapsing ice shelves.
As usual, for the Alaskan glaciers paper, I recommend reading the accompanying Perspective (Meier and Dyurgerov, 2002) first, then reading the scientific paper (Arendt et al., 2002). For the modeling work, I recommend reading the accompanying News Focus first (Tollefson, 2016) and then the scientific paper (DeConto and Pollard, 2016).
The discussion component of this activity will take place over Week 1 of this lesson and will require you to participate multiple times over that period.
You will be graded on the quality of your participation. Please see the rubric for teaching/learning discussions. [1]
One of the most common misconceptions about global climate is that the greenhouse effect is just a hypothesis whose role in recent climate change is debatable. In fact, the greenhouse effect is an observable fact of what goes on in our atmosphere. The sun's radiation is transmitted to the Earth through our atmosphere. Some of this radiation is reflected back out into space, but some of the radiation in the infrared spectrum gets absorbed and re-radiated by the greenhouse gases in our atmosphere. This warms up the surface of the planet and it's an extremely important effect because without it the planet would be way too cold for us to live on it. The schematic cartoon below depicts this. The main greenhouse gases are water vapor (making up about 2/3 of the total), carbon dioxide, and methane. These all occur naturally, but human activities have increased the concentrations of carbon dioxide and methane through industrial activities and clear-cutting forests. We've also synthesized some greenhouse gases that aren't naturally occurring and added those to the atmosphere, too.
Even though Earth's natural carbon cycle moves a gigantic amount of carbon between the land, sea, and atmosphere naturally, the balance is pretty delicate and the amount humans have been adding to the atmosphere since the Industrial Revolution lingers in the atmosphere for over 100 years. This means that the effects of climate change we feel now were produced by activities in the past. The fact that greenhouse gases keep being emitted by human activity now means that we have already committed to a warmer future.
The "Keeling Curve" might be the most famous plot of global climate data. Charles Keeling began measuring the atmospheric concentration of carbon dioxide at Mauna Loa in 1958. Today, four air samples an hour are collected from the observation towers at Mauna Loa and the concentrations of several gases are measured. The NOAA keeps track of observations from over 50 stations around the world. The average concentration of CO2 in the atmosphere has steadily increased ever since monitoring began.
Let's take a look at this plot together (oops! note that in my explanation I mistakenly say that the y-axis is carbon dioxide concentration in millimoles per mole of air when in fact it is micromoles per mole.):
In addition, check out this really cool animation that shows how carbon dioxide concentrations have increased in the atmosphere globally over the past few decades. In the video, the x-axis is latitude and the y-axis is CO2 concentration. The various different symbols represent different types of recording stations (tower, airplane, etc) and the line is an average value.
In this activity, you will use the Interactive Atmospheric Data Visualization tools of NOAA's Earth System Research Laboratory to create some plots of climate data that interest you.
Go to Interactive Atmospheric Data Visualization [155] and follow my directions:
The main page has an interactive map of the world with a bunch of colored dots on to designate places where atmospheric data is habitually collected by NOAA. You'll see that the default current selection is set to the Mauna Loa Observatory. Click “Carbon Cycle Gases” to expand that menu and then choose Time Series. You will be taken to a new page. Don’t change anything on the page, just scroll down and click the Submit button. You have just generated a time series plot of carbon dioxide concentrations recorded at 3397 meters above sea level at the Mauna Loa observatory. In fact, it is exactly the same plot we discussed on the previous page of this lesson, except more updated because I created that course page a while ago. Go ahead and try it! Then after you check out the plot, you can click the “Site Selection" link to get back to the original page we started on.
Now back at the original page, you see a world map and by hovering your mouse over the different circles you can find out the name of any station and what kind of samples it takes (carbon dioxide, methane, whatever) and how long the station has been active. If you click on one of the network station symbols, the menu side of the page changes so that you can make a plot of that station's atmospheric data. Go ahead and play around with this Web site. There's a lot of neat stuff here. You can always click “Site Selection" to get back to the original page we started on.
Pick two stations other than Mauna Loa and preferably ones that have at least a couple of years of data. It’s also interesting to pick one in the northern hemisphere and one in the southern hemisphere.
Make time series plots for both carbon dioxide (CO2) and methane (CH4) at your stations—that's 4 plots. You can save the plots to your computer by clicking where it says "PDF version" on the page where it makes your plot.
Create a word processing document (Microsoft Word, Macintosh Pages, Google Docs, or PDF) to record your work for this problem set.
Paste your plots into your document, and answer these questions.
People often wonder how there can be different interpretations of the same datasets. In Part 2 of this activity, we will deliberately set up a "strawman" of a dataset that has been selected to maximize the potential for incorrect interpretation in order to see how different interpretations can arise. To do this we will take advantage of the fact that there is natural variability in the concentration of CO2 in the atmosphere due to the seasonality of plant growth. We will make two plots, each containing several months of data at Mauna Loa.
Go to NOAA's Trends in Atmospheric Carbon Dioxide [156] page and follow my directions:
Scroll down to the bottom of the page so that you are looking at the plot called “Mauna Loa Daily,
Monthly and Weekly Averages for two years”
Use the slider bars below the plot to make the x-axis go from Oct 2017 to April 2018. Take a screenshot of this plot and include it in your document.
Use the slider bars below the plot to make the x-axis span June 2018 - October 2018. Take a screenshot of this plot and include it in your document.
Answer the Part 2 questions on your document.
Here are the Part 2 questions:
Upload your document to the "Lesson 5 - Keeling curve problem set" assignment in Canvas by the due date indicated on the first page of this lesson. Here's what should be in your document: 4 plots from part 1 and the answers to the part 1 questions; two plots from part 2 and answers to the part 2 questions. Name your document like this:
L5_keelingcurve_AccessAccountId_LastName.doc/.pdf/.pages
For example, Cardinals second baseman Kolten Wong would name his problem set L5_keelingcurve_kkw16_wong.doc
I will use my general rubric for grading problem sets [47] to grade this activity.
The world's climate system does not respond fully and immediately to externally applied forcing. This lag time has allowed the debate about the effect of human activities on climate to go on longer than it would have if everything we did were instantly noticeable. For example, when a certain amount of extra CO2 is added to the atmosphere, the warming effects on the air, land, and ocean take some time to be fully realized. Even if there was a way to add heat directly to the Earth, it would still take time for the temperatures we measure to increase. In this activity, we'll conduct a simple experiment to observe the specific heat capacity of water. By doing so, we'll be able to gain some insight about the lag time of the climate system's response to external forcing.
The specific heat capacity (Cp) of liquid water at room temperature and pressure is approximately 4.2 J/g°C. This means it takes 4.2 joules of energy to raise 1 gram (or 1 milliliter if you'd rather think of the equivalent volume of 1 gram of water) of water by 1 degree Celsius. This is actually quite large. The specific heat capacity of water vapor at room temperature is also higher than most other materials. Here is a table of the specific heat capacities of various materials:
Material | Cp(J/g°C) |
---|---|
liquid water | 4.2 |
air | 1.0 |
water vapor | 1.9 |
granite | 0.8 |
wood | 1.7 |
iron | 0.0005 |
Note that none of the other materials listed above come close to water's ability to absorb heat. (Nitpicker alert: Water does not have the highest known heat capacity. The heat capacity of pure hydrogen gas at room temperature is 14.3 J/g°C, according to the CRC Handbook of Chemistry and Physics. Pure H2 is not a big player in the Earth's climate system, though.)
The high Cp of water is why "a watched pot never boils!" This is also the main reason the climate is slow to respond to external changes. It is lucky for us that the ocean has the ability to absorb a lot of heat before its temperature rises appreciably. The flip side of this is that once an external source of energy is removed, the ocean is similarly slow to respond. Its temperature will not begin to decrease right away. In the next activity, we will observe this phenomenon.
The world climate does not respond immediately to the external forcings applied by human activity. A simple way to show why this is so is to make some simple observations about the heat capacity of water.
These are the materials you need for this lab: water, a pot, a thermometer, a stove or other heat source, a watch or other timer.
This is optional, so there is nothing to turn in for this assignment, but this is a fairly simple and instructive experiment, so give it a try if you get a chance!
See my plot below of two experiments in which I varied the initial volume of water in the pot. Note how much time it takes for the water to return to the starting temperature after boiling!
Now let's take a look at some predictions of future climate based on global climate models. Recall from Elizabeth Kolbert's article that there are several groups around the world in the business of producing, running, and tweaking global climate models. Each one is slightly different in the way it treats various Earth properties. For example, some climate models do a more extensive job of modeling the oceans, and others do a more extensive job of modeling atmospheric conditions, etc. Different climate predictions result from different initial conditions, different parameterizations of interactions between systems, and different assumptions about emissions into the future.
Climate scientists are often frustrated by the portrayal of different results as "scientists don't even agree on global climate change, so how are regular people supposed to know what's happening?" In fact, climate scientists do not disagree with the basic tenets of climate change. The fact that different global climate models output somewhat different results gives scientists better insight into the sensitivities of the models. All climate models that are part of the IPCC reports agree that the Earth's average temperature has increased since the Industrial Revolution. The exact details of how much warming, how that warming has been parceled out between reservoirs, and how much warming will continue into the future is debated among groups. It is statistically quite improbable that every group would be wrong and wrong in the same direction.
Recently, a survey was given to over 10,000 earth scientists to find out whether they thought that average global temperature has increased over the last two hundred years and whether human activities caused it. The results were that 90% think that global temperature has increased and 82% thought it was because of human activities (Doran and Kendall-Zimmerman, 2009). These findings are in contrast to another study that determined that only 52% of the general public thinks that climate scientists agree that the Earth is warming and that 47% of the general public believes that climate scientists agree that humans have caused it (http://www.pollingreport.com/enviro.htm) So, there is a definite discrepancy between what the scientific consensus is and what most people think the scientific consensus is.
I have chosen to discuss a few samples of model predictions from the Intergovernmental Panel on Climate Change for two reasons. The first is that its publications are the result of a huge collaborative international effort, so the plots you see below are have incorporated the widest agreement among climate scientists. Secondly, its estimates are pretty conservative (having to get past the most politicians) so we can proceed to look at their predictions without wondering whether these people are just a bunch of fringe group alarmist crackpots. They're not!
The first set of plots below shows a prediction of average global temperature rise from the present to the year 2100. The different line types represent several different model runs using six different "scenarios." These are called SRES scenarios and the main differences among them are the assumptions they make about the world's population and its greenhouse gas emissions into the future (i.e., whether emissions will continue to rise at today's pace, or whether emissions will stay at today's level but not continue to rise, or whether we will decrease emissions). The idea here is to bring climate modelers together, give them a suite of reasonable future scenarios, and then have them all run their models and see what the output is. Note that all models accurately reproduce past average temperature measurements (see right panel "1765–2100"). This is important because it establishes that these models can do a good job of "predicting" what has already happened. These models predict an increase in the global average temperature of between 1° and 6°C. Remember from our reading that during the last ice age the average temperature was only about 9°C colder than now.
Understanding how CO2 concentrations in the atmosphere will change in the future requires carbon cycle models which model the relationship between emissions and atmospheric concentrations. In the figure below, a few selected emission scenarios are shown in the left panel, and the estimated CO2 concentrations in the atmosphere for these scenarios are shown in the right panel. All three scenarios—even one in which we reduce our rate of emission—result in increased atmospheric concentrations that are well above pre-industrial levels by 2100 (75% to 220% higher). Climate-induced environmental changes cannot be reversed quickly. Even if the anthropogenic emissions of CO2 are stabilized or reduced, the CO2 content in the atmosphere will still increase for some time.
The paper detailing the study of Alaskan glacier wastage we read last week explains one of the results of a warming global climate: rising sea level. The plot below shows model predictions for global average sea level rise based on six emission scenarios. Think about how average sea level is measured. It's not so simple when you think about it. Remember from the tsunami lesson that at many places on the globe, daily tidal fluctuations are on the order of meters. Both tides and average sea level have natural seasonal variations, too. This means that average sea level must be measured carefully with respect to a reference point. It would be easy to produce a misleading dataset if measurements were taken haphazardly at different times of the year or without respect to some established baseline.
What effect does rising sea level have? What proportion of humanity lives within a meter of sea level? The model predictions in the plot below guess that by 2100 sea level might rise by about half a meter. These models probably err on the conservative side because they don't take into account as much glacial melting as many scientists now believe will happen.
Read the following articles, (linked directly from Canvas):
1. Plutzer, E., M. McCaffrey, A. L. Hannah, J. Rosenau, M. Berbeco, A. H. Reid, (2016) Climate Confusion Among U.S. Teachers. Science 351, 664-665.
2. Schiermeier, Q. (2010) The Real Holes in Climate Science. Nature 463, 284-287.
3. Kahan, D. (2010) Fixing the communications failure. Nature 463, 296-297.
And skim these two articles, (also linked directly from CANVAS):
4. Hegerl, G. (1998) Climate Change: Past as guide to the future. Nature 392, 758-759.
5. Mann, M. E., R. S. Bradley, and M. K. Hughes (1998) Global scale temperature patterns and climate forcing over the past six centuries. Nature 392, 779-787.
Climate scientists for many years hoped that the preponderance of observational data from a variety of sources would "speak for itself" and convince even the most jaded skeptics that the Earth is indeed warming. To their great dismay, the politics of global climate science continues to be as contentious as ever. As educators, it is up to us to train the world's future decision-makers. We need to make sure the general population has the ability to make logical conclusions based on observations, to evaluate a scientific argument, and to appreciate the social and psychological implications of the intersection of science and policy. I picked the articles above to get us thinking about these topics. A short preview of them:
Dan Kahan's article is an excellent piece on scientific communication and it explains how people align themselves with certain viewpoints. Quirin Schiermeier's piece is a straightforward treatment of what we don't know about Earth's climate. He makes an important point that every minute scientists waste debating facts that nobody should dispute is a minute not spent searching for the answers to the pressing knowledge gaps he writes about.
The other two articles are science research articles. The 1998 paper by Mike Mann and coauthors is the one that has the original "hockey stick" graph (reproduced above) that shows the recent abrupt upward swing in global temperatures based on a variety of observed and proxy data. The piece by Gabriele Hegerl is a "News and Views" article, similar to other ones you've read before in this class. The point of a "News and Views" article in Nature is to summarize a research paper in the same issue, putting it into context so that other scientists outside the field may appreciate the original article's impact. I put Mike Mann's article in our course reserves precisely because I think it is important for you to be exposed to the actual science at the heart of the controversy, as opposed to only hearing the spin on either side of the debate. Let me point out that I am only asking you to skim this article because it is extremely complicated and lengthy. It was not written for a general audience of nonscientists! In fact, you'd have to be pretty far inside the loop to make a considered judgment of their statistical analysis and evaluate all the different datasets that went into this paper. I still think you should have a look at it, though.
You will be graded on the quality of your participation. Please see the rubric for teaching/learning discussions. [1]
The purpose of the following activity is to introduce you to an interesting and simple climate model that can be run fairly easily on a Web browser. The main thing I want you to do is to fiddle around with this model, try things, and see what happens. Pretty vague directions, huh?! But there's a catch. The deliverable for this activity will be that you come up with a short lesson based on using this model that you think would be appropriate for students. This will aid your thinking about your capstone project for this course.
L5_lessonplan_AccessAccountID_LastName.doc (or .pdf).
For example, St Louis Cardinal third base coach and former "secret weapon" Jose Oquendo's file would be named "L5_lessonplan_jmo1_oquendo.doc" You can look it up: his given name is José Manuel Roberto Guillermo Oquendo Contreras.
Upload your file to the Java Climate Model dropbox in CANVAS by the due date indicated on the first page of this lesson.
I will use my general grading rubric for problem sets [47] to grade this activity.
Dessler, A.E. and E.A. Parson. (2006). The Science and Politics of Global Climate Change: A Guide to the Debate, Cambridge University Press, 190pp.
Doran, P.T. and M. Kendall Zimmerman. (2009). Examining the Scientific Consensus on Climate Change, Eos 90, 22-23.
Gehrels, W. R., B. P. Horton, A. C. Kemp, and D. Sivan. (2011). Two Millenia of Sea Level Data: The Key to Predicting Change, Eos 92, 289-290.
Hegerl, G. and P. Stott. (2014). From Past to Future Warming, Science 343, 844-845,
Howat, I. M., K. Jezek, M. Studinger, J. A. MacGregor, J. Paden, D. Floricioiu, R. Russell, M. Linkswiler, R. T. Dominguez (2012). Rift in Antarctic Glacier: A Unique Chance to Study Ice Shelf Retreat, Eos 93, 77-78.
Mote, P., L, Brekke, P. B. Duffy, and E. Maurer. (2011). Guidelines for Constructing Climate Scenarios, Eos 92, 257-258.
Pierrehumbert, R. T. (2011). Infrared radiation and planetary temperature [167]. Physics Today, 64(1), 33-38.
Rowley, R. J., Kostelnick, J. C., Braaten, D., Li, X., & Meisel, J. (2007). Risk of rising sea level to population and land area. Eos, 88(9), 105–107.
One of the great challenges ahead in climate modeling is to extend the results of global climate models to make predictions about what will happen at the regional or local level. Where will there be more extreme weather? What areas will experience more rainfall and where will there be extensive droughts? How will the addition of cold fresh water to the oceans change the ocean's circulation pattern? These changes are coming because of the anthropogenic forcings we have already added to the climate system. It yet remains for public policy and mitigation efforts to catch up with and support the scientists who study global climate.
You have finished Lesson 5. Double-check the list of requirements on the Lesson 5 Overview page to make sure you have completed all of the activities listed there before beginning the next lesson.
Lesson 6 will take us two weeks complete, but PSU has a week-long Thanksgiving break, so I'll make the due date after that. This lesson is the capstone project for this course, in which you are free to design your own course module, based (as much or as loosely as you want) on one of the topics we covered in the earlier lessons of this course.
By the end of Lesson 6, you should be able to:
The chart below provides an overview of the requirements for Lesson 6.
Lesson 6 will end on 3 Dec 2019
Requirement | Details | Due Date |
---|---|---|
Choose a topic | Just email me a brief description of your plan | 19 Nov (end of week 1) |
Capstone project | Submit this to the Capstone project assignment in Canvas | 3 Dec |
Student Educational Experience Questionnaire | This is optional and anonymous but useful for me. Please do it! It won't take you long. It's linked from Canvas in the Lesson 6 module | 13 Dec |
If you have any questions, please post them to our Questions? discussion forum (not e-mail). I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
I chose the topic of contemporary Earth sciences controversies because I wanted to focus on issues that wouldn't necessarily be covered in a textbook since they are ongoing and unresolved debates. I tried to put together a mix of types of controversies . . . for example, the New Madrid seismic risk controversy pits scientists against each other but also pits scientists against policymakers. On the other hand, mass extinction controversies do not involve any public policy. I also wanted you to participate in the process of science by carrying out analyses as well as reading research papers. I used publicly available datasets because I hoped that if you found any of the analyses interesting, you could easily co-opt them for your own use. The "teaching and learning" discussions were intended to get you to think about how you might use some of this material if you wanted to turn around and teach it, and also to think about necessary science skills independent of science content.
My guess is that you can take bits and pieces of this course and transform them into a lesson for your own use. Now is the time to prove it!
In this activity, you will design a lesson for an audience of your choosing based on one of the topics we covered in this course.
Save an electronic version of your activity in the following format:
L6_capstone_AccessAccountID_LastName.doc/.pdf/.pages/.your extension
For example, Cardinals manager and former catcher Mike Matheny would name his capstone project L6_capstone_msm1_Matheny.doc
Upload your capstone project file to the Capstone project assignment in Canvas by the due date on the first page of this lesson.
I am interested in the scientific accuracy of the topic you choose to teach and how well your lesson incorporates scientific thinking skills.
I am not going to base my grade on whether you have constructed a lesson plan in some special way (as long as all the components listed above are there). My assumption is that for those of you who are teachers, you don't need me to tell you how to write a lesson plan because you already know. For those of you who are not teachers, I am not the one who is going to instruct you on correct lesson plan-making. However, I am a scientist, so if facts are not right, or could use clarification, I can assist with that.
This has been fun and hopefully, you've had a useful experience and learned a few things in this course. I'd like science to be more interesting and more accessible to more people. You are free to use any of the lessons and activities from this course for your own purposes in teaching. If you do, I'd love to hear about it.
You have finished Lesson 6. Double-check the list of requirements on the Lesson 6 Overview page to make sure you have completed all of the activities listed there.
Glad you asked! If you liked this course, here are some others we are offering during the Summer 2017 semester:
EGEE 401 [168]: ENERGY IN A CHANGING WORLD
EARTH 540 [169]: Oceanography for Educators
There are two C I (curriculum and instruction) courses that are required for the program
C I 501: Teaching as Inquiry
C I 550: Overview of Contemporary School Curriculum
A complete course calendar for the M.Ed. in Earth Sciences program can be found at the M. Ed. in Earth Sciences website [170]
All the data analysis activities, regardless of length or difficulty, are worth 100 points because that makes my life easier. I make each numbered problem worth the same number of points also. So, if there are 10 problems, they are each worth 10 points. If there are 8 problems they are each worth 12 points (and I spot you the other 4 points because I’m just that benevolent).
My grading procedure is as follows:
My numerical grading scale (i.e. what range of scores equals an “A” or a “B”, etc.) can be found linked under Syllabus in the menu bar.
Go to the New Madrid Earthquake Catalog [115]
Now you will be taken to a page titled Catalog Search Results. From here you will want to click the link to "View or Download Catalog Search Results." This will bring up a plain text file that you can save to your own computer somewhere that you can find it later.
Once you have downloaded that file, hit the back button on your browser to return to the Catalog Search Results page. Choose any of the options you want and then hit the button that says "Generate Map." You will be taken to a page with a map of the earthquakes in your catalog. Save this map by right-clicking the image (control-click on a Mac), or taking a screenshot of it.
Go to the Southern California Earthquake Data Center [118]. Click the link for "SCSN Catalog Search."
On this page:
Still on the catalog search page,
Now you can download your map or take a screenshot of it to save it.
Go to the USGS Earthquake Search [120] page. Once you are there
Watch the videos below to see how I set up my data tables and make the plots for the earthquake catalog problem set in Lesson 4. In my example, I use Numbers, a mac spreadsheet program similar to excel.
In the first video, I show you how I sort the data in order to make counting a large number of earthquakes a straightforward and efficient process.
If you still aren't sure how to make a table of values out of your sorted list of magnitudes, watch the second video (below):
Want some further tips on how to make the plot after you've constructed your table of values? Watch the third video (below):
Having trouble plotting more than one dataset on the same axes? The video below gives some tips for doing this in Numbers.
If you are an excel user, much of the functionality of the program is similar to numbers, but if you have run into trouble making logarithmic axes, here's how:
Links
[1] https://www.e-education.psu.edu/earth501/sites/www.e-education.psu.edu.earth501/files/file/rubrics/Online_Discussion_Forum_grading_rubric.pdf
[2] https://www.google.com/maps/d/u/0/edit?mid=1ObsKk6WAcprDR_rehLm75KTEDxQ&ll=30.49600888001862%2C-101.42589725950086&z=4
[3] https://www.softintegration.com/
[4] http://chartpart.com/
[5] http://nces.ed.gov/nceskids/createagraph/default.aspx
[6] http://gcalc.net/
[7] http://www.openoffice.org/product/index.html
[8] http://webapps.psu.edu/
[9] http://google.com
[10] http://www.synergy.com/
[11] http://www.redrocksw.com/index.php?option=com_content&view=article&id=8&Itemid=33
[12] http://www.pmel.noaa.gov/tsunami/indo_1204.html
[13] http://tsunami.org/tsunami-signs/
[14] http://www.boston.com/news/world/articles/2004/12/28/ne_is_not_immune_scientists_warn/
[15] http://www.es.ucsc.edu/~ward/papers/La_Palma_grl.pdf
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