Goals

Earthquakes were instrumental data used by geologists to unravelling the location and nature of plate boundaries. In this exercise you will evaluate the most recent earthquake data and determine if they support what you've learned about the distribution of earthquakes relative to plate boundaries.

Supporting skills: geography, calculation of percent, identification of range, data organization and critical thinking, report writing

Instructions

Be prepared to spend at least an hour at the computer getting your data. You will need to explore the links for each earthquake so you can determine their location and assign them to a plate boundary. Beware: This list changes daily so if you miss something important you might have to start over. You will not be able to access the same data list.

Completed work must be neatly typed, referenced,and proofread.

Procedure:

1. Go to the sites listed below and print out the following:

   <http://wwwneic.cr.usgs.gov/neis/current/world.html> USGS Earthquake information: Map of current world seismicity (map of the last 21 earthquakes worldwide).  You can obtain a more detailed map showing the location of an earthquake relative to a plate boundary by double clicking the epicenter tag on the map.You may find the "historical seismicity" link informative

2. Click on Near Real Time Earthquake List and print out the list of earthquakes
3. You can also get a local map by double-clicking on an earthquake in the list.
4. Both the world map and the list of earthquakes are to be included in your report.

Using the real-time earthquake map that you just printed, this Tectonic map compiled by researchers at NASA's Goddard Flight Center, and a map of plate boundaries fill out the table below. You should be able to interpret the tectonic setting of each earthquake from its location on the map.

Tectonic setting	Total number of earthquakes for each setting	% of all earthquakes	range of magnitudes
Plate boundaries	.	.	.
subduction zone	.	.	.
zone of continental convergence	.	.	.
mid-oceanic ridge	.	.	.
zone of continental rifting	.	.	.
transform boundary	.	.	.
Intraplate	.	.	.

%=(number in each setting/Total number of earthquakes)*100

range = lowest-to-highest values. For example for a set of date obtained on 1/5/2001 the magnitudes of earthquakes along divergent boundaries ranged from 2-4.5. This Table must be completed and incorporated into your report. Click here to obtain a clean blank copy with caption.

Part II: Write a report (25).

Write a two- to four-page typed paper that covers the topics listed below. Use the topic headings as subheadings for your report. The text of your report should be in your own words and not copied from the textbook or from other sources. All books and sites used for reference must be listed and properly cited in a bibliography at the end of your report. Any figures used must have figure captions and must be reference if taken from a book or website.

Topics:

1. Causes of earthquakes (5) Write an introductory paragraph explaining the causes of earthquakes according to the elastic rebound theory. Include such terms as stress, strain, strength of the rock, rupture, etc.
   
2. Distribution of earthquakes (10) After reviewing you lecture notes and researching the topic write a section on the global distribution of earthquakes. Include a discussion of the relationship between plate tectonic setting, the distribution of epicenters, and the distribution and depth of hypocenters.
   

   Your discussion should answer the following questions.

   a. Where do the majority of earthquakes occur and why?

   b. What are intraplate earthquakes and what are some of the hypotheses presented to explain them?

   c. According the the plate tectonic theory how and why do hypocenter depths vary along transform boundaries, divergent boundaries, continental-continental convergent boundaries, and subduction zones.  Is this supported by your data?

3. Discussion of listed earthquakes (10) Discuss the earthquakes on your list. Here you will use the data from your table. The point of this section is to see whether or not the relationships outlined above are actually supported by the data. Keep in mind that the 21 earthquakes on your list is a very small statistical sampling. Don't forget to mention the dates of the earthquake data that you're using (e.g. March 21-23/2001).
   

In this section the following questions should be addressed.

a. Where are the earthquakes concentrated? And why?

b. What percentage are intraplate? What percentage occurred along plate boundaries. What percentage occur along each type of plate boundaries?

c. Does the data you've collected support the relationships discussed above. Mention and discuss any relationship between plate boundary earthquake depths.

Bibliography and Appendix

Bibliography page: This page must include references to texts or sites that you used to write this report. See syllabus for proper reference format. You may include illustrations to aid your discussion. However, any illustration obtained from a written or online source must be referenced in the figure caption and in the Bibliography.

Appendix: Include the map and list of recent earthquakes in an Appendix at the end of your report.

• Grading form

Lindley Hanson/Department of Geological Sciences/Salem State College