103-5 Beyond Epicenters: Enhanced Information from Seismograms for Introductory-Level Students

Session: Balancing Tradition and Innovation: Evolving Geoscience Curricula for a Changing World (Posters)

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Many beginning seismology exercises use S-P wave travel time differences to determine the epicentral distance of a seismic event from multiple seismic stations, and then "triangulate" to the epicenter. The exercise often ends there. But while epicenter location is important and likely the first thing one would want to know about a seismic event, we believe even introductory-level students should be exposed to the wider breadth of information that can be obtained from analysis of seismic waves. This includes two types of information: information about the event itself and information about the medium through which seismic waves travel, i.e. Earth. In our 100-level Natural Hazards course for non-STEM students, the seismology activity starts with students using three-component seismograms to determine epicentral location of a large earthquake near a plate boundary. But then, they go on to calculate a body-wave magnitude for the event, analyze 1st P-wave "ups" and "downs" to define possible focal plane solutions, and determine the possible types and orientation of faulting that could be responsible.  Follow-up applications include consideration of why the epicentral distance circles don't intersect at a point like they do in textbooks, why there is variation of magnitude as measured at different stations, how best to express the magnitude, whether the type of faulting matches the plate tectonic setting, whether a nuclear bomb test could have been responsible for the event rather than fault displacement, and whether a tsunami would likely be generated by the event. Thus, students not only learn how to locate the source of a seismic event, but also wrestle with measurement variation, discover the heterogeneity of Earth’s interior, relate their results to plate tectonic setting, and apply their results to natural hazard assessment. The presentation will include teaching materials, aids that facilitate visualization of “beachball” projections of first P-wave motions, and examples of student work.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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