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Section 12
Earthquake Magnitude

In this section you will find materials that support the implementation of EarthComm, Section 12: Earthquake Magnitude.


Learning Through Technology

To learn more about seismic waves, complete the following:

Measurement of Earthquake Wave Amplitude

  1. Visit the Virtual Earthquake website at http://www.sciencecourseware.com/VirtualEarthquake/.    The Virtual Earthquake website will help you to simulate a new earthquake.

    1. pencil Follow the directions to calculate the magnitude of the earthquake.
    2. pencil How does the amplitude (height) of a seismic wave change when the size of an earthquake changes?
    3. pencil How would you expect the amplitude as recorded on a seismogram to change as you get farther from the epicenter?

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Inquiring Further

  1. To learn more about detecting and recording earthquakes, visit the following web sites:

    Did You Feel It?, USGS
    Contribute your intensity observations of an earthquake that you experienced.

    Earthquakes and Seismicity, USGS
    Describes the energy released by an earthquake. Includes a good explanation of the difference between intensity and magnitude.

    Earthquake Intensity Database Search, NOAA
    Includes an earthquake intensity location map of North America. Allows searches for specific earthquakes by city and state, so you can look up the intensity of earthquakes that have shaken your community.
  1. To learn more about the ways earthquakes are measured, visit the following web sites:

    Seismometers, Seismographs, and Seismograms, etc., USGS
    Explains how seismographs work, includes diagrams of seismographs and also reviews P and S wave motion and explains how to read Travel-Time curves.

    Global Seismographic Network, USGS
    Description of the Global Seismic Network (GSN) and how it is used to study earthquakes around the world.

    Monitoring Earthquakes Around the World, USGS
    Brief description of how seismograph stations are used to monitor earthquakes.

  2. To learn more about tsunami warning system in the Pacific, visit the following web sites:

    Tsunami: the Great Waves, NOAA
    Describes the causes of tsunamis as well as how they are detected by the Tsunami Warning System (TWS) in the Pacific.

    NOAA Center for Tsunami Research, NOAA
    Describes research and development efforts in tsunami monitoring networks. Includes data on recent tsunamis and spectacular animation.

    Local Tsunamis in the Pacific Northwest, USGS
    History of local tsunamis, including geological evidence and legends surrounding these giant waves.

    Tsunami, FEMA
    Reviews what a tsunami is and what kinds of damage are typically associated with a tsunami occurrence.

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Resources

To learn more about this topic, visit the following web sites:

Seismometers

Seismometers, Seismographs, and Seismograms, etc., USGS
Explains how seismographs work, includes diagrams of seismographs and also reviews P and S wave motion and explains how to read Travel-Time curves.

How are Earthquakes Studied?, Michigan Technological University
Includes a photograph and description of the first device used to detect earthquakes and an illustration showing how seismograms are generated.

"The Early History of Seismometry (to 1900)," by James Dewey and Perry Byerly, USGS
Series of "chapters" which detail the early development of instruments used to detect and measure earthquake activity.

Interpreting Seismograms

How Do I Read a Seismogram, Michigan Technological University
Includes images to help you to learn to read seismograms.

Seismometers, Seismographs, and Seismograms, USGS
Descriptions of how seismometers, seismographs, and seismograms are used to monitor volcanic eruptions.

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