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Homework #3

Geography of Seismic and Volcanic Hazards

Due in class Thursday, July 20


Purpose:

As a group, you are to research the geographic distribution of earthquakes, and volcanoes, and plate boundaries at various scales using GIS:


1
Global/National

Earthquakes, volcanoes, and plate tectonics.

Using ArcVoyager, your textbook, and the online sources, follow directions and answer the the following five questions about the geographic patterns you see:

In ATC 304, 1. Turn on two computers side by side. On one computer open ESRI World Thematic Data , and on the other, open the locally installed ArcVoyager, and read the Guide that appears, to learn the basics of using this GIS. When you get to the Point Me section, choose the Physical Geography project, and click on the magnifying glass icon near the top to open the project.

Question 1: Are earthquakes evenly distributed around the earth? If they are not evenly distributed, where are earthquakes concentrated, and what patterns can you see?

2. At the left part of the screen is the Table of Contents; each item listed is called a Theme. Though the "Major Lakes" and "Major Rivers" themes are interesting, they will get in our way for these activities, so turn them off by clicking on the checkmark for each theme. This is the way to turn any theme off or on.

3. Scroll down the list of themes, and turn on "Major Earthquakes 1970-93". You might not be able to see all of this theme's title; if you need to check it, put the cursor on the gray bar on the right side of the Table of Contents and drag the right edge farther right - but don't leave it there because you will want the space in the map window for future work. Compare the with the location of volcanoes.

Question 2: Are there more earthquakes and volcanoes at or near plate boundaries, or more away from the boundaries?

4. This pattern of earthquakes and volcanoes on the earth has helped scientists determine that the surface of the earth is actually not solid and continuous, but instead is made of pieces, called tectonic plates, which can move. It is the movement of these plates which causes earthquakes.

a. To see the relation between the plates and the earthquakes, turn on the "Plates" theme. But now we have a problem: since ArcVoyager draws each visible theme starting at the bottom of the Table of Contents and working towards the top, the Plates cover the dots for the earthquakes, so we can't see the relationship between them.

b. To fix this, scroll the Table of Contents so you can see the Major Earthquakes theme, but there is also some room above the Plates theme. Then move the cursor onto the Table of Contents, and to somewhere on the Major Earthquakes theme name. Then click the mouse and hold it, and drag the Major Earthquakes theme to just above the Plates theme, and release the mouse button. Now the Plates theme will plot first, and the earthquake dots will be drawn on top of the plates.

Question 3:

Using ArcVoyager (only in ATC 304), your textbook, and ESRI World Thematic Data (online), compare and contrast the kinds of earthquakes and volcanoes and landforms associated with the following locations:
 region

type
 earthquakes  volcanoes  landforms

 Western California

transform boundary
   (None, why not?)  

Western Washington State

convergent boundary
     

  Iceland

divergent boundary
     

 Hawaiian Islands

 hotspot
     

What to look for:
earthquakes: strength, frequency, depth, what kind of fault?
volcanoes: composite or shield types?, effusive or explosive eruptions?
landforms: mountains, ocean trenches, rift valleys, island arcs, etc.
Try to relate all of these to the part they play in the rock cycle and plate tectonics system.


2
Regional/Local

Your Bay Area neighborhood - assessing earthquake hazard:

Determine the location of your neighborhood on a map of the bay area. Then, using the Bay Area Shaking Hazard Maps found at the ABAG Earthquake Maps and Information website , try to determine the potential for damage to your neighborhood due to an earthquake. You may choose any scenario or shaking intensity maps to analyze various aspects of vulnerability.

Question 4: What are the main faults in the Bay area? Which one is closest to your neighborhood?

Question 5: Please explain what accounts for the seismic hazard in your neighborhood, and the variation in hazard throughout the Bay Area. Aside from proximity to the epicenter and fault, what are other important factors in determining the pattern of seismic hazard?

Documentation:

Hand in the anwers to your questions along with all of the maps and other data used in your research. Don't forget to include full citations and a bibliography to tell me where you got your maps and other information. For more information, please read how to hand in assignments.


Questions one and two were adapted from a lesson on earthquakes and plate tectonics titled "Making Earthshaking Discoveries." Author: Martin F. Schmidt, Jr.
available at: http://gis.esri.com/industries/k-12/arclessons/arclessons.cfm

Related links:

ESRI World Thematic Data

ABAG Earthquake Maps and Information
Comprehensive earthquake related info

Mitigation Techniques: Make your home safer.

Community Preparedness Website Project

Earthquake Information from the USGS
USGS National Earthquake Information Center

Northern California Earthquake Data Center Home Page

Plate Tectonics and Earthquake Links