Measuring Depth to Bedrock Using Seismic Refraction

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This material was developed and reviewed through the IGUaNA curricular materials development process.

This material was developed and reviewed through the IGUaNA curricular materials development process. This structured process includes:

Iterative review and feedback cycles throughout the course of material development with input to the author(s) from the project team;
Pilot testing of materials in courses at multiple institutions; and
Pre-publication review to ensure the materials meet the standards in the IGUaNA module rubric.

This page first made public: Apr 16, 2021

Summary

This module is designed to introduce students to geophysical concepts and related earth science principles to illustrate how geophysics can be used to 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, PA. There is also an option to collect and analyze one's own seismic refraction data, using instrumentation resources available at the IRIS PASSCAL Instrument Center.

This module is intended to require approximately two (2) weeks of class time, excluding the optional collection and analysis of one's own data. Teaching material includes PowerPoints that may be used in lectures or provided for self-guided learning, Excel-based exercises to guide students to an understanding of the mathematics that underpin seismic refraction, and handouts that ask students to synthesize what they learn from the exercises. In addition, multiple choice and short answer questions can be given to students as homework, on quizzes, or on exams. The Codorus Creek case study culminates in a report, and a rubric is provided for evaluating those reports.

Strengths of the Module

Use of real data: Authentic datasets are used throughout the module, even for the simplest exercises. This allows students to grapple with the challenges of real data sets, where there is an element of interpretation in choosing where and how to measure variables. It also shows students how geophysics is used in real-world settings.

Connects students to the world around them: This module emphasizes how seismic methods are used to address problems or answer questions that apply to our everyday lives. The Codorus Creek case study, in particular, shows how seismic refraction can help inform and guide an urban renewal project.

Flexibility: This module can be used as individual units or as a complete module. Unit exercises can be used as homework or in-class/lab assignments. Exercises can be completed individually or in small groups, and several of the seismic refraction data sets can be analyzed using a jigsaw approach if desired.