3. Earthquake Tracking

Objective:

To gain a deeper understanding of the relationships between earthquake locations and plate tectonics, and to monitor global earthquake activity on a weekly basis.

Activities:

Form groups of students. Three-to-four students works well, but the size of the groups will depend on the size of your class and how your classroom is set up. There are various activities that are part of this exercise, and these different activities can be divided among the groups as appropriate for your classroom situation.

The first activity involves capturing and printing seven complete (24 hour) daily screen shots from your seismograph for the previous week and analyzing these seismogram screen shots for earthquakes. This may involve capturing multiple overlapping seismograms per day to capture a complete 24 hours of seismogram activity. To access the BC seismograph screen, plus the seismograph screens from Weston Observatory and some of our BC-ESP schools (updated every 5 minutes) go to:

www2.bc.edu/~kafka/Seismograph_Display/bc_esp_as1.html.

To see a larger (printable) version of these seismograms, click on View Larger Image of Seismogram.

Your group’s task is to print two seismogram screen shots each day—one in the morning and one late in the evening, to assure that you captured the full 24 hours worth of daily seismic activity. You may have to save the image to your desktop (as a GIF file) first and then open it and print it in order to get the entire screen shot. At the start of each week, one of the groups will analyze these seismograms for earthquakes by highlighting and identifying earthquakes (or anything else interesting that was recorded), and give a brief presentation of findings to the class.

The next activity involves using the Internet to compile and print a list of the coordinates, magnitudes, and dates of earthquakes that have recently occurred. The information for this list can be obtained from the National Earthquake Information Center (NEIC) web site.

For the customized search, you will be able to input various parameters for your search, such as: range of dates, range of magnitudes, and format of output.

Next you will plot the locations of the previous week’s earthquakes. Make two different plots, one for all of the earthquakes reported on the NEIC web site for the past few days, and another for the entire week but only including those earthquakes of magnitude 5.0 or greater. As the weeks progress, compare the results for all earthquakes for a few days versus a cumulative plot of only those of magnitude 5.0 or greater. Which of these plots gives the best demonstration of how earthquake locations are related to the theory of plate tectonics? Why?

An Excel spreadsheet for plotting epicenters on a map of the world is included with this activity. You may want to plot different maps for different aspects of this exercise. If so, just make copies of the Excel file, and modify it as necessary. Each week the class will watch for patterns in the distribution of epicenters that emerge over time, and will discuss the extent to which the emerging pattern of epicenters is consistent with the theory of plate tectonics.

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