Student-centered Experiments on Earthquake Occurrence Using the Seismic/Eruption Program
Jeffrey S. Barker
Department of Geological Sciences and Environmental Studies, Binghamton University
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Students select their own region of interest and interrogate the earthquake catalog to obtain quantitative data on the rate of occurrence of earthquakes of various magnitudes within their chosen region.
High school Earth Science students, introductory Physical Geology course for non-majors, lower-level Geophysics/Tectonics course for majors.
Skills and concepts that students must have mastered:
To run a Windows PC program, to plot data on a semi-log graph, and to interpret that graph.
How the activity is situated in the course:
As an ?exploration? activity following an ?engagement? demonstration on earthquake occurrence and plate tectonics.
National or State Education Standards addressed by this activity?:
Content/concepts goals for this activity:
Global seismicity; distribution and rate of occurrence of earthquakes.
Higher order thinking skills goals for this activity:
Making observations, interpreting data, drawing conclusions, prediction and hypothesis testing.
Other skills goals for this activity:
Writing a lab report, making a semi-log graph and identifying patterns in data.
Description of the activity/assignment
Students, working individually or in small groups, run the free Windows program Seismic/Eruption to generate maps from an earthquake database accurate and complete from 1960 to the present. Students select a seismically active region of interest to them and make their own map. They also select a time window, perhaps 20 years. By changing the minimum magnitude threshold setting in Seismic/Eruption and replaying the plots, they observe first-hand that large earthquakes occur less often than smaller magnitude earthquakes. The total number of earthquakes plotted is easily read from a counter on the screen. Students build up a table of the number of earthquakes per year with magnitude greater or equal to a certain magnitude, using a wide range of magnitude thresholds. These are then plotted on semi-log paper in the form of a Gutenberg-Richter plot. Connecting the points on the plot allows students to see a linear trend, to interpolate and extrapolate from the points measured, and to think about why there may be departures from that linear trend for very small and very large magnitudes. If they assume earthquake occurrence in their chosen region is equally distributed in time, they can predict how often an earthquake of a given magnitude is likely to occur. They can also replay Seismic/Eruption to see whether that assumption is valid.
Determining whether students have met the goals
Students write a short report of their observations and conclusions in terms of the following questions: Do you see any patterns or trends in earthquake occurrence in your region? Are the numbers of earthquakes in the smallest and largest ranges consistent with the trends in the other ranges? Can you think of any reasons why the database might not be complete for large magnitudes? How about for small magnitudes? What is the likelihood that an earthquake of magnitude 7.0 or greater (which can cause severe damage) will occur in the next year in your region? Be sure to include your database search results (the numbers of earthquakes within various magnitude thresholds and the Gutenberg-Richter plot), along with the limits of dates, latitude and longitude you used in your search.
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