GETSI Module: Measuring Depth to Bedrock Using Seismic Refraction Open

Advanced

This module introduces students to using the active seismic method and illustrates how geophysics can inform engineering projects in an urban environment. Students are first introduced to seismic data as individual waveforms, allowing them to explore the relationship between wavelength, frequency, and travel time. They explore the fundamental equation governing seismic refraction, Snell's Law, and then use seismic refraction data to interpret subsurface geology from a small survey on the University of Wyoming campus. Finally, they use seismic refraction data to evaluate the subsurface geology for an urban renewal project along Codorus Creek in York, Pennsylvania.

Students can collect and analyze their own seismic refraction data, using instruments available at the EarthScope Primary Instrument Center (instructions for making an educational use request are on the EarthScope Geophysics Field Education page).

Objectives:

A great fit for courses in:

  • Geology
  • Environmental Science
  • Earth Science
  • Earth System Science
  • Geophysics
  • Physics
  • Engineering

Related Animations

Seismic waves travel at different speeds through different materials. In this 2-layer model two wave fronts leave an impact at the same time but the lower layer is faster. 

Animation Novice

Animation shows the race between the direct seismic wave vs. the deeper, longer-path critically refracted seismic wave. Graph records the arrival times.

Animation Novice

In this model of increasing velocity with depth, the critically refracted seismic rays speed up with depth as they pass 5 different velocity boundaries.

Animation Intermediate

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Like other waves, seismic waves obey the laws of physics. In this activity Physics students have the opportunity to apply their understanding of the basic concepts of waves (e.g. reflection, refraction and transmission of energy) as they examine seismic data to determine how far it is from the surface to the bedrock.

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