Part 4—Investigate Earthquakes and their Distribution

Step 1 Launch My World and Set up the Map

  1. Launch My World.
  2. Make sure you are in Construct mode. (Click the "Construct" tab at top of screen to change modes).
  3. Select Geology from the Data Library pull-down menu.
  4. Click and drag the following layers to your Layer List:
    • *Continents
    • *Plate Boundary Types
    • Earthquakes - Medium 4.0-5.9 (2001-2003)

    • Optional:
    • Earthquakes - Big 6.0-9 (1994-2003)
    • Earthquakes - Small 2.0-3.9 (2001-2003)
  5. If you are continuing from Part 2 the first two layers will already be on your map.
  6. Switch to Visualize mode by clicking the Visualize tab.

Step 2 Explore the Depths of Earthquakes

  1. Open the table of the layer for the Earthquakes Medium... layer to investigate its contents. Sort the "Depth and Magnitude" fields ascending and descending. Note the ranges of values for both of these fields.
  2. Legend Tip: You can toggle a layer's legend on and off by selecting the "Hide/Show Color Legend" button.

  3. Close the Table of the Layer.
  4. Use the map to explore the visual patterns in Earthquake locations? Provide a possible reason why Earthquakes occur in these locations.
  5. Create a series of selections of shallow (0-199) and medium (200-399) and deep (400 and greater) earthquakes using the 'select by value' in Analyze mode.
  6. Highlight Mode Tip: After making a selection in Analyze mode, try different Highlight Modes to see different ways to display your selection functions of earthquake medium .
  7. Select the earthquakes by magnitude.
    • Select items from "earthquakes medium..." whose "depth is greater than "400." Provide a result name that will describe the selection.
    • Return to Analyze mode and create the additional selections from "earthquakes medium..." Provide result names that will describe the selection.
  8. Consider the following questions:
    • Switch between the different selections and make observations of where earthquakes of different depths occur.

    • Where do the deepest (400km and greater) earthquakes occur?

    • Why do you think earthquakes are deepest at these locations?

    • Where do the shallowest (0-199km) Earthquakes occur?

    • Why do you think earthquakes are shallowest at these locations?

Step 3 Observe the Relationship between Earthquake Patterns at Different Types of Plate Boundaries

Now that you have investigated seafloor age and volcano activity, you will look for one more relationship in support of the theory of plate tectonics. To do this, turn on the Plate Boundaries layer and observe the relationship between plate boundary types and earthquake patterns.
  1. Consider the following questions while looking at the map:
    • What is the pattern of earthquake depths at a divergent boundary?

    • What is the pattern of earthquake depths at a convergent boundary?

    • What differences do you notice between these two boundary types?

    • Is the pattern of earthquakes similar on both sides of the plate boundary? Explain the pattern you observe.
    • Summary question: For each boundary type, list evidence you've discovered that describes plate movement.