Part 3—Explore Earthquakes and Seismic Waves

Step 1 Add Earthquakes and Shear Wave Velocities Layers

Earthquakes generate seismic waves that move through Earth. Changes in the speed of some of these wave help scientists learn about Earth's structure. In this step, you'll compare the types of plate boundaries with seismic shear wave velocities near them. You'll observe different types of plate boundaries around the world and the pattern of shear wave velocities near them.
  1. If necessary, launch My World and open the Seismic Wave.m3vz project file.
  2. Select the Zoom to Full Extent button to ensure that you are at the full world view. Turn off the Tectonic Plate names layer. Make sure only the Plate Boundary Types and Countries layers are turned on.


  3. Observe the distribution of tectonic plate boundaries around the world. What do the different colored plate boundaries represent?
  4. Turn on the Seismic S-wave Velocity at 100 km layer. Observe the relationship between color and velocity for this layer. The values are in kilometers per second (km/sec). What color represents the slowest shear wave velocity? What color represents the fastest?
  5. Turn on the Earthquake layers. What do you notice about the distribution of earthquakes and the plate boundaries?
  6. In the next few steps, you'll examine the relationship among shear wave velocities at a depth of 100 km, types of plate boundaries, and earthquake locations. You'll examine these data for Japan, India, and the middle of the Atlantic Ocean.

Step 2 Examine Data near Japan

  1. Use the Zoom In tool to Zoom In on the area around Japan.

  2. Save your work as a new 'Map View'. Click the Map View pull-down menu located above the map. In the save the current as... dialog box, type the word "Japan."
  3. Examine the plate boundary near Japan.
    • Is this a convergent or divergent plate boundary?
    • Turn on and activate the Tectonic Plate Names layer. Use the Get Information identify tool to determine which plates are east and west of the boundary.
  4. Look at the distribution of Seismic S-wave velocities on each side of the plate boundary. How do the velocities you observe on each side of the boundary compare to one another? (Hint: you may need to turn Earthquakes and Tectonic Plates off to see the colors.)
  5. How are the earthquakes distributed on either side of the plate boundary - evenly or only on one side?
  6. Can you think of a reason for this pattern of shear wave velocities and earthquakes?
  7. You may want to examine shear wave velocities near other locations along this plate boundary to see if the relationship you discovered holds true.

  8. Zoom back out to the full world view by clicking the Zoom to Full Extent button.

Step 3 Examine Data near India

  1. Zoom In to the area around India.

  2. Save your work as a new 'Map View'. Click the Map View pull-down menu located above the map. In the save the current as... dialog box, type the word "India."
  3. Examine the plate boundaries near northern India.
    • Is this a convergent or divergent plate boundary?
    • Identify the tectonic plates north and south of the boundary.
    • In terms of geographic features, how is India different from Japan?
    • What major mountain range is located along India's northern border?
    • Are the earthquakes evenly distributed on each side of the plate boundary or only on one side?
  4. Look at the distribution of S-wave velocities on each side of the plate boundary. How do the velocities you observe on each side of the boundary compare to one another?
  5. Can you think of an explanation for the shear wave velocities being faster south of the Himalayas?
  6. Zoom back out to the full world view by clicking on the Zoom to Full Extent button.

Step 4 Examine Data in the Mid-Atlantic

  1. Zoom in on the Mid-Atlantic Ridge.

  2. Save your work as a new 'Map View'. Click the Map View pull-down menu located above the map. In the save the current as... dialog box, type the word "Mid-Atlantic."
  3. Examine the plate boundary.
    • What is the primary type of plate boundary here?
    • Which plates are on the east and west side of the boundary?
  4. Look at the shear wave velocities on each side of the plate boundary. Are they similar on each side?
  5. How are the earthquakes distributed in regard to the plate boundary - evenly or or only on one side?
  6. Can you think of a reason for this pattern of velocities and earthquakes?
  7. Examine more plate boundaries around the world. See if the patterns you discovered in shear wave velocities at the three plate boundaries above can be generalized for the whole world. If you find locations that exhibit a different pattern, hypothesize about the factors that might be affecting that situation.

Step 5 Save your Work

  1. Zoom back out to the full world view by clicking on the Zoom to Full Extent button.
  2. Save your edited project with a new name such as: Seismic Wave Part 3.m3vz. Save the file to a location where you can locate it easily, such as the desktop or your documents folder, if you are using a shared computer.