Unit 1: Introducing Shallow Seismology to Explore Our Subsurface Environment

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People collecting seismic data on a street overlooking Reno, NV.

Provenance: J. Louie, UNR
Reuse: If you wish to use this item outside this site in ways that exceed fair use (see http://fairuse.stanford.edu/) you must seek permission from its creator.

Unit 1 Learning Outcomes

Students will be able to:

• Explain what practitioners in the field of geophysics do,
• Use concepts related to waves to calculate the speed of sound in the Earth,
• Give examples of how seismic refraction is used by science and industry,
• Describe the importance of seismic refraction measurements to geoscience explorations of urban and wildland environments
• Describe the relationship of seismic wave frequency content to the distance from a source.

Unit 1 Teaching Objectives

• Affective: Motivate students interest in geophysics with examples relevant to urban and environmental geophysics
• Cognitive: Empower students to place their geoscience and geophysics learning in the context of a classification hierarchy

This first unit is intended for students without exposure to geosciences or geophysics and may be a first exposure to the concept of measuring earth's subsurface environment to support research, industry, and management tasks in the context of daily life.

Part 1: Introduction to geophysics and seismic refraction

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Students operating a computer during a seismic measurement, Reno, NV.

Provenance: J. Louie, UNR
Reuse: If you wish to use this item outside this site in ways that exceed fair use (see http://fairuse.stanford.edu/) you must seek permission from its creator.

This part introduces students to the concepts of geophysics and refraction seismology. Context is given for how seismic refraction may be used in science and industry. Here we focus on examples from the built environment. The importance of seismic refraction is explained, and relevance to daily life is presented.

Materials provided:

• PowerPoint introduction to geophysics and seismic refraction (PowerPoint 2007 (.pptx) 20.3MB Sep2 24)
• Student handout, Introduction to seismic refraction (Microsoft Word 2007 (.docx) 76kB Sep8 24): This handout is intended for students to follow along during the lecture to make sure they are getting the important information from it. It covers materials from both PowerPoint presentations.
• An answer key for the questions in the handout is available for instructors. See the "Assessment" section of this page, below.

Part 2: Speed of sound, waves, and bedrock

This part introduces the parts of a wave related to the speed of sound. The concept of bedrock is explained, along with examples of how bedrock is important for science and engineering applications, and how these are related to seismic geophysical imaging.

Materials provided:

• PowerPoint presentation on speed of sound, waves, and bedrock (PowerPoint 2007 (.pptx) 14.6MB Sep2 24)
• Student handout, Introduction to seismic refraction (Microsoft Word 2007 (.docx) 76kB Sep8 24): This handout is the same handout provided in Part 1. It is intended for students to follow along during the lecture to make sure they are getting the important information from it. It covers materials from both PowerPoint presentations.
• Wave frequency exercise (Excel 2007 (.xlsx) 1.1MB Sep18 24)
  • Wave frequency exercise - worked example (Microsoft Word 2007 (.docx) 88kB Sep18 24) - worked example can be shared with students to help them check their work
  • Text from Wave frequency exercise XLS (Microsoft Word 2007 (.docx) 17kB Sep8 24): This document provides step-by-step instructions for students to complete the wave frequency exercise. These instructions are also embedded in the spreadsheet.
• Seismic velocity exercise (Excel 2007 (.xlsx) 776kB Sep18 24)
  • Seismic velocity exercise - worked example (Microsoft Word 2007 (.docx) 534kB Sep18 24) - worked example can be shared with students to help them check their work
  • Text from Seismic velocity exercise XLS (Microsoft Word 2007 (.docx) 542kB Sep15 24): This document provides step-by-step instructions for students to complete the seismic velocity exercise. These instructions are also embedded in the spreadsheet.
• Answer keys, solution sets, and a grading rubric are available for instructors. See the "Assessment" section of this page, below.

Instructors may provide a review of Microsoft Excel (and analogous free software) to students before Exercise 1.

The Excel-based exercise can be completed using a Team-based learning (TBL) or a Jigsaw approach:

• The students could be divided up into small groups (~3 students per group), with each team calculating the wavelength of one of the waveforms provided.
• After calculations, all groups could add their results to a large graph for the whole class on the whiteboard. If more than three groups are in the class, differences between calculated results could be plotted together and discussed in the context of uncertainty.
• Finally, small groups could discuss the possible reasons for the trend in the x-y plot and list ideas on the board for a class-wide discussion.
• If the students struggle with the exercises, start by providing the "Worked Examples" that break down the work into more explicit steps and do not use Excel. If the students are struggling with the Excel implementation, consider providing the key or "solution" Excel workbook sheets in part or in whole so they can see how to enter the formulas. Alternatively, show the solution sheets to the whole class, and then have the students go back and reproduce the results themselves.

• The Excel-based exercises provided in the Teaching Materials section of this page may be completed by students for a grade, using this rubric for Excel-based exercises (Microsoft Word 2007 (.docx) 75kB Sep8 24)
• Assessment questions, intro to seismic refraction (Microsoft Word 2007 (.docx) 84kB Sep8 24). These questions can be given to students as homework, on quizzes, or on exams.

Solutions for instructors

• Answer key, student handout, intro to seismic refraction -- private instructor-only file
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• Answer key, assessment questions, intro to seismic refraction -- private instructor-only file
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• Answer key, Wave frequency exercise -- private instructor-only file
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• Answer key, Seismic velocity exercise -- private instructor-only file
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Making this module work in your course

Additional exercises related to bedrock and the environment may be accessed here:

• Bedrock geology mapping exercise
• Geology and geomorphology exercise
• Urban Environmental Excursions: Field Trips to Connect Urban Geology Students with the World around Them

Here is a MATLAB toolbox for reading raw SEGY files for download