EARTH 520
Plate Tectonics and People

Activity: Constructing a P Wave Travel Time Curve

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Sidelight: Note about my teaching philosophy

If you aren't really interested in finding out why I chose to make the problem set this way, don't keep reading this section, but sometimes I like to be able to explain why I decided to teach a topic a particular way. . .

In my courses, I like to use data that is openly accessible by you and requires little or no preprocessing by me to make it usable. I do this on purpose because I want you to be able to go to the place where we got this data and get more if you want to, or repurpose it for your own classroom in a way that makes sense to you. I want you to be able to do this later on without needing me! On the other hand, sometimes there's a measurement or an observation I want you to be able to make without spending hours wrestling with an unfamiliar file format. That's the situation with the seismograms for this exercise. If you were all Ph.D. students of mine who were hoping to become card-carrying seismologists, then I would tell you that it is important for you to delve into the exciting nuances of seismic data files. But you aren't, so I don't want to make you spend hours on that problem when all I want you to do is to pick some P waves, construct a travel time curve, and think about the physics that makes it work.

If you are interested in how I produced these plots, I made an appendix page to this lesson where you can see exactly what I did. If you ever do want to construct your own exercise like this one using different data, but you get stuck, feel free to contact me, or the folks at IRIS, for help!

Station Records

The earthquake whose waveforms we'll use for this exercise should be ingrained in your recent memory. It happened in Haiti on 12 January 2010. The origin time is 21:53:09 (UTC--all times are given in UTC) Its coordinates are lat = 18.45 N, lon = 72.45 W, depth = 10 km. It was a mag 7.0 event. For all the records below, we will look at long-period data, which is recorded every one second. I have given you a one-minute window around the P wave arrival. In order to construct a travel time curve, you need to pick the P wave arrival, subtract that time from the origin time of the event and plot that travel time vs. the distance between the station and the earthquake.

Record 1: Station: 230A - Sterling City, TX, USA
Network: TA - USArray Transportable Network (new EarthScope stations)
Lat: 31.89 Lon: -101.11 Elev: 742.00

Record 2: Station: 734A - La Parita Creek, Jourdanton, TX, USA
Network: TA - USArray Transportable Network (new EarthScope stations)
Lat: 28.85 Lon: -98.56 Elev: 121.00

Record 3: Station: ANTO - Ankara, Turkey
Network: IU - Global Seismograph Network (GSN - IRIS/USGS)
Lat: 39.87 Lon: 32.79 Elev: 1090.00

Record 4: Station: COLA - College Outpost, Alaska, USA
Network: IU - Global Seismograph Network (GSN - IRIS/USGS)
Lat: 64.87 Lon: -147.86 Elev: 200.00

Record 5: Station: H17A - Grant Village (NPS), Yellowstone Nt. Park, WY, USA
Network: TA - USArray Transportable Network (new EarthScope stations)
Lat: 44.40 Lon: -110.58 Elev: 2400.00

Record 6: Station: I03D - Drain, OR, USA
Network: TA - USArray Transportable Network (new EarthScope stations)
Lat: 43.70 Lon: -123.35 Elev: 140.00

Record 7: Station: I28A - Midland, SD, USA
Network: TA - USArray Transportable Network (new EarthScope stations)
Lat: 44.00 Lon: -101.17 Elev: 655.00

Record 8: Station: K21A - Alcova, Casper, WY, USA
Network: TA - USArray Transportable Network (new EarthScope stations)
Lat: 42.63 Lon: -107.25 Elev: 1960.00

Record 9: Station: KEV - Kevo, Finland
Network: IU - Global Seismograph Network (GSN - IRIS/USGS)
Lat: 69.76 Lon: 27.00 Elev: 100.00

Record 10: Station: KIEV - Kiev, Ukraine
Network: IU - Global Seismograph Network (GSN - IRIS/USGS)
Lat: 50.70 Lon: 29.22 Elev: 180.00

Record 11: Station: KMSC - Kings Mountain, Blacksburg, SC, USA
Network: TA - USArray Transportable Network (new EarthScope stations)
Lat: 35.14 Lon: -81.33 Elev: 240.00

Record 12: Station: KONO - Kongsberg, Norway
Network: IU - Global Seismograph Network (GSN - IRIS/USGS)
Lat: 59.65 Lon: 9.60 Elev: 216.00

Record 13: Station: LCO - Las Campanas Astronomical Observatory, Chile
Network: IU - Global Seismograph Network (GSN - IRIS/USGS)
Lat: -29.01 Lon: -70.70 Elev: 2300.00

Record 14: Station: PAB - San Pablo, Spain
Network: IU - Global Seismograph Network (GSN - IRIS/USGS)
Lat: 39.54 Lon: -4.35 Elev: 950.00

Record 15: Station: PMSA - Palmer Station, Antarctica
Network: IU - Global Seismograph Network (GSN - IRIS/USGS)
Lat: -64.77 Lon: -64.05 Elev: 40.00

Record 16: Station: Q29A - Oakley, KS, USA
Network: TA - USArray Transportable Network (new EarthScope stations)
Lat: 38.89 Lon: -100.98 Elev: 895.00

Record 17: Station: RCBR - Riachuelo, Brazil
Network: IU - Global Seismograph Network (GSN - IRIS/USGS)
Lat: -5.83 Lon: -35.90 Elev: 400.00

Record 18: Station: SDV - Santo Domingo, Venezuela
Network: IU - Global Seismograph Network (GSN - IRIS/USGS)
Lat: 8.88 Lon: -70.63 Elev: 1620.00

 

Record 19: Station: TEIG - Tepich, Yucatan, Mexico
Network: IU - Global Seismograph Network (GSN - IRIS/USGS)
Lat: 20.23 Lon: -88.28 Elev: 40.00

Record 20: Station: TIXI - Tiksi, Russia
Network: IU - Global Seismograph Network (GSN - IRIS/USGS)
Lat: 71.63 Lon: 128.87 Elev: 40.00

Record 21: Station: TRIS - Tristan da Cunha
Network: IU - Global Seismograph Network (GSN - IRIS/USGS)
Lat: -37.07 Lon: -12.32 Elev: 60.00

Record 22: Station: TRQA - Tornquist, Argentina
Network: IU - Global Seismograph Network (GSN - IRIS/USGS)
Lat: -38.06 Lon: -61.98 Elev: 540.00

Record 23: Station: WCI - Wyandotte Cave, Indiana, USA
Network: IU - Global Seismograph Network (GSN - IRIS/USGS)
Lat: 38.23 Lon: -86.29 Elev: 210.00