Learning With Data Map Activity: A study of tectonic plate boundaries
Refer to your National Geographic Map, The Earth's Fractured Surface, and your copy of the Physiographic Chart of the Seafloor. Similar maps may be substituted. Use "Area Maps" to get a closer look at the margin you are investigating.
A. Convergent Margins or Subduction Zones
Looking at your map of the tectonic plates on
Earth’s surface, choose several convergent plate boundaries. Use
the “Map” module and draw several profiles through the convergent margin you
What do the profiles look like? Describe and sketch the general shape, and label the different parts.
What is happening at this convergent margin?
What types of lithosphere plates are involved? Is it an oceanic-oceanic convergent zone, an oceanic-continental convergent zone, or is it a continental collision zone, where continental lithosphere collides but is not subducted?
Add the Earthquake data. It will automatically give you an earthquake profile for the last profile you created. If you want to see the earthquake profile for one of your other profiles, choose it under the profile button and then click on "update."
What does the earthquake profile look like?
What is the depth of the deepest earthquake?
Why do you think the
profile looks this way? (Remember what kind of plate boundary this is.)
Add the volcano data
Are there volcanoes nearby?
Do they appear to be
in a line or randomly placed? Why?
B. Divergent Margins or Spreading Centers
Depending on the rate of spreading between tectonic plates, there is a great deal of physical variation in divergent margins. Using the “Map” tool, draw several profiles across divergent margins you have identified using your map.
What is the maximum
elevation of your profile? Is this above or below sea level?
Sketch the general shape of your profile.
Where do earthquakes appear to be concentrated?
What is the maximum depth of the earthquakes?
How does this
compare to the maximum depth of the earthquakes at convergent margins? Is it
shallower or deeper?
What is happening at your divergent margin? Is it a mid-ocean ridge or a land-based rift?
Add the volcano database. Remember from the tutorial that data along mid- ocean ridges is under-represented. Do you remember why? Recall that mid-ocean ridges are very far beneath the surface of the ocean.
C. Transform Margins or Strike Slip Faults
Use your National Geographic map to identify transform faults (remember, you live near one). Use the map tool and draw several profiles across transform margins you have identified with your map. Because of the scale of the data, these boundaries may be difficult to identify. Zoom into Western California and try making several profiles across the San Andreas Fault zone. You ought to be able to find some evidence (in profile) of this tectonic boundary. Once you have found a good profile, then add the earthquake data.
What is the deepest earthquake?
How does this compare to the maximum depth of the earthquakes at convergent margins? Is it shallower or deeper?