Long-Wavelength Waves: Tsunamis or Harbor Waves.
Among the most devastating coastal catastrophes are tsunamis or harbor waves. Although they are very infrequent, when they do occur, they can travel large distances across ocean basins and result in significant destruction and loss of life. The four projection maps shown in Figure 5.21, show the areas of the globe that are most prone to tsunami generation (i.e., shown in red highlights). Most of these areas are identified as high risk for generating tsunamis because, not only are they plate boundary areas, they are also associated with subduction zones where two tectonic plates collide and one is pushed below another. These maps and information about simulating tsunami events for predicting their travel and impacts are from NOAA's Center for Tsunami Research.
If you haven't already, please take a few minutes to read this web article (USGS Circular 1187) titled: Surviving a Tsunami—Lessons from Chile, Hawaii, and Japan that is on the Module 5 Roadmap. The link provides some important details about tsunamis and some critical information items on how to survive an event if you are ever faced with the need to do so.
Unfortunately, tsunamis and the earthquakes that produce them are not readily predicted, although some regions are more prone to their occurrence than others. NOAA and its research partners are working and collaborating on ways to detect these events and, as needed, are working on strategies to notify people around the world of a tsunami event should one be detected. A variety of tools are used today by geoscientists to help detect these phenomena and, as much as possible, to warn residents and coastal communities of their potential occurrence. We will learn later in the module about tools and the data they collect. However, detecting tsunamis was not always possible, and we still have limitations. Historically, tsunamis have caused incredible numbers of deaths, with single events capable of the loss of hundreds of thousands of people at a time.