Earthquakes

When the earth shakes, people pay attention. Most earthquakes result from movements of the rocks within the Earth’s crust. Stresses that build up over time, generally as a result of plate tectonics, reach the point where the rocks can no longer resist or accommodate the pressure by elastic deformation, so a rupture results. The sudden release of energy generated an earthquake. Although we are aware of large earthquakes in populated areas, there are many smaller quakes that occur daily around the world. The smaller quakes may not be felt by humans, but can be recorded by a seismograph. All earthquakes provide us with information about planet Earth and the tectonic processes that continue to occur.

All students in Prof. Anderson’s classes:

Make sure to include the Indonesia, Dec. 26, 2004 earthquake and tsunami in your research.

Part 1         About Earthquakes

To learn something about earthquakes, start by going to the University of California, Santa Barbara Institute for Crustal Studies at:

http://www.crustal.ucsb.edu/ics/outreach// or

http://www.crustal.ucsb.edu/ics/outreach/understanding/

• Take the Earthquake quiz.
• Then return to the Understanding Earthquakes page.
• Try the How Earthquakes occur animation.

Even if your browser does not allow you to view the animation, you can still read the information presented and may be able to view the static images.

• Answer the questions on the worksheet.
• Before leaving the starting page, as time permits, check out the Famous Earthquake Accounts. They are eyewitness writings.

Part 2: What’s Shaking?

• Visit the USGS National Earthquake Information Center at:

http://wwwneic.cr.usgs.gov/

• Navigate through the different topics presented to answer the questions on the worksheet.
• Now go to Current Seismicity Information
• Start with Finger qk_info@gldfs.cr.usgs.gov.
• Scroll down to the section on Additional information. Select one of the other specific region sites, as directed by your professor. If none was given, then select one of interest to you. Access the site using the address given. You may need to prefix the address with http://

For example: to go to the Southern California site, direct your browser to: www.scecdc.sec.org.

or

http://www.scecdc.org.

• Next, choose the “List of Recent Earthquakes….”

Some sites have a different format, but you can find the same type of information. For example, for the Northern California site for Berkeley, at: quake.geo.Berkeley.edu

You would go – under Data Retrieval from the NCEDC – through Retrieve, search, or browse data from the NCEDC to reach a page that gives you the choice of:

Finger quake@quake.geo.berkeley.edu

There you will receive a list of the recent quakes for that region. Answer the questions on the worksheet.

Telnet for quakes

You can check the information available from the NEIC on the internet in a different way. This will require that you leave your browser and use Telnet. After earthquakes have scrolled off the NEIC “quake” list on their Web page, they are available in updated form from the Quick Epicenter Determinations (QED) bulletin board. To access QED, use the Telnet command “telnet neis.cr.usgs.gov ,” log in as QED and follow the on-line directions. Note that Telnet is not like finger. You will need to interact with the QED to obtain what you want.

Part 3: Images of Earthquakes

Images of over 80 earthquakes are available at the Earthquake Engineering Research Center at: http://www.eerc.berkeley.edu/

• Take the link: EqIIS – Earthquake Image Information System.

You can go directly to some of the collection’s images for specific earthquakes using the links provided.

You may also go through Query EqIIS and look up any of the Archived materials by name. For example:

· Anchorage, Alaska, 1964

· Mexico City, Mexico, 1985

· San Francisco, 1906

• Download images on one or more earthquakes and answer the questions on the worksheet.

Part 4: Tsunami

• Go to the University of Washington Geophysics Program at:

http://www.geophysics.washington.edu/

• Choose the links Seismology and Earthquakes and then select Tsunami information.
• Answer the questions on the worksheet.

Earthquakes Worksheet

Part 1: About Earthquakes

1.         Earthquake Quiz. How did you do?

Introduction to Elastic Rebound Animation.

1. Which earthquake led to the development of the currently accepted theory of how earthquakes occur?

2. How far could the fault associated with this earthquake be traced, and what was the maximum displacement observed along this fault?

Part 2: What’s Shaking?

National Earthquake Information Center

1. What are the main missions of the NEIC?

2. On average, how frequently do great earthquakes (as defined by the magnitude) occur?

3. What are some differences between the magnitude and the intensity of an earthquake?

4. How many different magnitude scales are there in use at present, and why are there so many?

Recent Earthquakes

1. What are the dates covered in this table?

2. What is the largest magnitude earthquake that is listed, what was the depth (DEP) to the hypocenter, where did the earthquake occur, and what type of magnitude is given?

3. What was the largest magnitude earthquake that occurred in North America during this time period, and where did it occur?

Area of your Choice

1. What site have you chosen?

2. What organization maintains the site?

3. What are the dated covered in the recent listing?

4. What is the largest magnitude earthquake that is listed, what was the depth (DEP) to the hypocenter and where did the earthquake occur?

Part 3: Images of the Earth

1. Which earthquake did you choose (date, location, magnitude)?

2. What was the image?

3. Why do you think the photographer chose this subject?

Part 4: Tsunami

Physics of a Tsunami

1. What is a tsunami?

2. What kind of events can generate a tsunami?

3. What is the literal translation of the word tsunami, and from what language?

4. How do tsunamis differ from other water waves?

5. How fast can a tsunami travel in the open water of the Pacific Ocean?

6. What happens to a tsunami as it approaches land, enters shallower water, and slows down?

Great Tsunamis

1. List the four most recent great tsunamis.

2. Of the four most recent great tsunamis described, which caused the largest loss of life and greatest property damage?

Tsunami Hazard Mitigation

1. If you hear a warning or think a tsunami might be coming, what is the single most important thing to do if you are on land?

2. If you are on a boat, where is the safest place for your boat to be?

3. Write down one of the “Important Facts to Know about Tsunamis” that you think is especially worth remembering.