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#### Summary

This activity takes place in a laboratory setting and requires ~1.5-2 hours to complete. Students read and interpret seismograms, determine the epicenter of an earthquake by triangulation, and learn how to enter data in a spreadsheet.

## Context

#### Audience

Undergraduate class on introductory physical geology, natural hazards or quantitative reasoning for non-majors

#### Skills and concepts that students must have mastered

Must have basic knowledge about earthquakes: magnitude, depth, epicenter, P- and S-waves

#### How the activity is situated in the course

This activity follows lectures on earthquakes. It is the first laboratory exercise in the course and introduces computer spreadsheets.

## Goals

#### Content/concepts goals for this activity

Read seismograms, identify arrival times of P- and S-waves, and use a travel time curve to obtain the distances from the seismometers to the epicenter

#### Higher order thinking skills goals for this activity

Calculate the time that the earthquake occurred, locate the epicenter by triangulation, and graphically determine the local magnitudes of the earthquake

#### Other skills goals for this activity

Enter data and a formula in a spreadsheet, compute the average magnitude of the earthquake, translate algebraic expressions to spreadsheet format

## Description of the activity/assignment

In this activity, students work with data from an earthquake in South America. Student materials include a Microsoft Excel spreadsheet with marked cells and cells to enter data, a PDF with seismograms, travel-time curve and nomogram, and the instruction sheet. The exercise is divided into three parts.

Part I introduces the concept of a seismogram. Students identify P- and S-wave arrival times and use the differences to obtain distances from a travel-time curve.

In Part II, students work with GPS Visualizer to triangulate the epicenter online and with a nomogram to determine the local magnitude of the earthquake as recorded by each seismometer.

Part III involves an introduction to spreadsheets using a workbook with prepared worksheets. Finally, students rewrite algebraic expressions in computer terms for entering formulas in spreadsheets.

## Determining whether students have met the goals

In both the traditional face-to-face and online versions of the course, this activity is assessed based on the answers to the questions. It is also possible to have students submit their completed spreadsheets, although this option works best in a small class.

## Supporting references/URLs

Michigan Technical University, 2007, How do I locate that Earthquake's Epicenter? Online resource – Accessed June 15, 2019
http://www.geo.mtu.edu/UPSeis/locating.html

Wald, L., The Science of Earthquakes: Online resource – Accessed June 15, 2019
https://earthquake.usgs.gov/learn/kids/eqscience.php

Earthquake Hazards Program: Online resource – Accessed June 15, 2019
https://earthquake.usgs.gov

M 8.3 Illapel, Chile, earthquake: Online resource – Accessed June 15, 2019
https://earthquake.usgs.gov/earthquakes/eventpage/us20003k7a/executive

Schneider, A., 2019, GPS Visualizer: Onlinw resource – Accessed June 15, 2019
http://www.gpsvisualizer.com/map_input

Microsoft, 2018, Excel for Windows Video Training: Online resource – Accessed June 15, 2019