Initial Publication Date: June 22, 2010

Week 7: Investigating Earthquake Activity

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Using My World to Analyze Earthquake Patterns

The roads near Hebgen Lake, Montana after earthquake, August 1959. Close-up of fractured Highway. Source: USGS Photo archives.

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Key Investigation Questions:

  • How are earthquakes distributed?
  • Where do really big earthquakes occur?
  • How do recent quakes compare with the historical record?


 
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Introduction

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Earthquake Patterns

Earth is a dynamic planet. Its crust is continuously forming and deforming, constantly pushed and pulled as it moves. When strain that has built up over time is suddenly released, the crust shakes, and we call this movement an earthquake. Depending upon their strength and where they strike, earthquakes can inflict severe property damage and claim thousands of lives.


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Launch My World and Open the Earthquakes Project

My World Icon

  • Launch My World by double-clicking its icon on your desktop or by clicking its icon in the Dock (Mac) or Launch Bar (Win).
  • Choose File > Open Project, navigate to Applications/My World/data/EarthquakeMW, select the E_QuakesMW.m3vz file, and click Open.
  • A global map will open with the Continents, U.S. States, and Lines of Longitude and Latitude on the map.

 



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Examine a Year's Worth of Earthquake Data

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Add earthquake data from 2009

  • Click the Add Layer from File add layer from file button. The Import Data File window opens.
  • Navigate to the csv_files folder within the EarthquakesMW folder. In that folder, select the 2009EQ.shp file that was created the last time you added this data as Import Text Data. Then click OK.
  • Click on the 2009EQ label in the Layer List. Then select Table of Layer.
  • Look at the upper left corner of the Table of Layer to find out how many earthquakes with a magnitude of 4.0 or greater occurred in the past year. (Remember that this data set has only earthquakes with a magnitude of 4.0 or greater.)
  1. In Visualize mode click the Add Layer from File add layer from file button. The Import Data File window opens. Navigate to the EarthquakesMW folder. In that folder, select the 2009EQ.shp file that was created the last time you added this data as Import Text Data. Then click OK.
    3 import 2009 EQ file
  2. Click on the 2009EQ label in the Layer List. Then select Table of Layer.
  3. Look at the upper right corner of the Table of Layer 2009EQ to find out how many earthquakes of a magnitude 4.0 or greater occurred in 2009.
    31 2009 EQ table


How many earthquakes of a magnitude of 4.0 or higher occurred in 2009? Look on the map, what do you notice about the distribution of these earthquakes?

What do you now notice about the distribution of earthquakes?

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Examine the Distribution of Past Significant and Big Earthquakes

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Add the significant and big earthquakes from 2150 BC to 2007 AD

The Significant and Big Earthquakes will now be displayed on the map along with the 2009 Earthquakes.

36 big sig on map top of page

Compare Earthquake Distributions

  1. Click and drag Plate Boundary types in the Layer List
    37 move layer up
  2. This is what the map looks like with the plate boundary layer on top.
    38 PB are on top


What type of plate boundary is associated with the historical Significant and Big earthquakes (i.e. ones that have a magnitude of 7.0 or greater)?

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Where are the Big Earthquakes Mostly Likely to Occur in the Future?

As you discovered, most "big" earthquakes are concentrated at convergent plate boundaries. It is possible to characterize a risk zone using a GIS. For example, through querying and buffering, we can find out how many magnitude 7.0 or greater earthquakes have occurred within a specified distance of a plate boundary.

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Select convergent plate boundaries

  1. In Analyze mode. Choose Select ... by Value Plate Boundary type whose Margin Type matches 'Convergent'.
  2. Click OK. 
    40 margin type is convergent
  3. Here is what the map looks like with the convergent plate boundaries highlighted.
    41 margin type conv OK


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Select earthquakes from the sig_big layer that are within a specified distance

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Show the results of the spatial query

  1. Make sig_big the active layer by clicking once on its name in the Layer List. Then select Table of Layer.
    44 attribute table
  2. Scroll the Attributes of sig_big to view the selected records.


What percentage of big earthquakes occur within 100 miles of a convergent plate boundary?

What percentage of big earthquakes occur within 200 miles of a convergent plate boundary?

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How does the 2010 Earthquake Pattern Stack Up?

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Select the Chilean earthquake

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Discover how far this earthquake was from a major city

How would you discover the distance that this earthquake was from a major city?

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Show me the result

 

Use the procedure above to investigate the Haitian earthquake.

 

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Explore More if you have Time


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