PLATE TECTONICS DATA ONLINE
OBJECTIVES:
1. The student will become familiar with the function of the USGS as a data resource and
information gathering agency.
2. The student will access current geological information and report the results of an
internet data resource.
INTRODUCTION:
The USGS or United States Geological Survey keeps significant quantities of geological
data online for student access as an educational or statistical tool. The USGS web site
describes its government organization as the following:
“Created by an act of congress in 1879, the USGS has evolved over the ensuing 120
years matching its talent and knowledge to the progress of science and technology.
Today, the USGS stands as the sole science agency for the Department of the Interior. It
is sought out by thousands of partners and customers for its natural science expertise and
its vast earth and biological data holdings. The USGS is the science provider of choice in
accessing the information and understanding to help resolve complex natural resource
problems across the Nation and around the world.”
Today you will survey information from the USGS and other sources to determine some
vital tectonic statistics.
PROCEDURE AND ANALYSIS:
1. Go to http://sideshow.jpl.nasa.gov/mbh/series.html, which is a site summarizing data
collected from satellites used to accurately measure the movements of the tectonic
plates. Refer to the figure labeled “Global Velocities” toward the bottom of the page
and answer the questions for #1.
2. Next we are going to look a little closer at some tectonic plate movements underneath
the Pacific Ocean. Click on link below and answer the questions for #2.
http://cddis.gsfc.nasa.gov/slrtecto/swpactect.html
3. Now look at the map of South America at http://bowie.gsfc.nasa.gov/926/soamtect.html and
answer the questions for #3.
4. Now we are going to explore the thickness of the Earth’s crust. Go to
http://earthquake.usgs.gov/data/crust/ and check out the map of the thickness of the Earth’s
crust at various locations and fill in the table below on the map and answer the questions for #4.
5. Now go to the diagram at http://earthquake.usgs.gov/data/crust/cascadia.php which is a graph
of the Cascadia Subduction zone off of Oregon’s coast, and answer the questions for #5. See
bottom of diagram to enlarge.
6. Access the following site: http://pubs.usgs.gov/publications/text/dynamic.html.
Summarize the information described at this site for question #6. (HINT: The Preface
is good place to start.)
DATA, OBSERVATIONS, and ANALYSIS:
Answer the following questions on your own headed paper.
1a. What does the length of the black arrow represent? What does the direction the
arrow points indicate?
1b. What direction is most of North America moving (assume the top of the map is
north)? Approximately how far does it move in one year?
1c. Now look at Europe. What direction is it moving? How far does it move in one
year?
2a. What direction is Maui moving? Does the set of undersea mountains northwest of
Maui line up with the arrow? Why do they line up so closely?
3a. What direction is the Nazca plate, on which Easter Island is located, moving?
3b. What direction are the mountains along the coast of South America moving (i.e. at
Santiago)?
3c. Earthquakes and volcanic activity suggest that the Nazca is sub ducting underneath
the South American plate. How is this happening if both plates are moving in the
same direction?
4a. Select the most extreme value for a given region (thickest or thinnest point):
Geographic Region, Crustal Thickness (km), Himalayas (North of India), Atlantic
Ocean, Pacific Ocean, West Coast of South America, Western United States, and
Australia.
4b. Why is the crust the thickest underneath the Himalayas?
5a. What is the light blue material at the upper left side of the diagram with a density of
1? (Hint: recall the specific gravity exercise we did in lab)
5b. Approximately how deep does the green continental crust extend below the Western
Cascades? What is the approximate density of the continental crust?
5c. How does the density of the sub ducting slab compare to that of the mantle (pink
material in the lower part of the diagram)?
Pink Mantle_____________________ Subducting Slab________________________
6. Summarize the information provided by The Dynamic Earth.