Objectives:

• Discover and characterize regional and global patterns of earthquake distribution.

Background: The San Francisco Bay area is, of course, not the only part of the world where earthquakes occur—they are also a prominent feature of life in lots of other places, including other parts of California. In this exercise we will investigate where earthquakes tend to occur and where they don't, and try to characterize the patterns that we find.

Pedagogical Strategy: In Part I, working with the members of your permanent group, you'll use earthquake distribution maps to try to identify patterns of earthquake distribution both in California and globally.

Detailed Instructions:

Working with the other members of your permanent group, develop a consensus response to questions about the several maps below. Select a spokesperson to communicate your consensus response to the rest of the class.

1. Click on the link below to see a map (provided by the U.S. Geologic Survey) that shows the locations of earthquakes in California and Nevada during the last week:
   

   Recent earthquakes in California and Nevada:
   (http://quake.wr.usgs.gov/recenteqs/latest.htm)
   

   1. According to the information accompanying this map, how many earthquakes occurred in California and Nevada during the last week?
      
      
   2. Were they distributed more or less randomly, or does there appear to be a pattern to their distribution? Describe any patterns that you see.
      
      
   3. The map provides information about the magnitudes of the earthquakes that occurred, based on the momentum magnitude scale (which has replaced the older Richter scale). What range of magnitudes did recent earthquakes in California and Nevada have?
      
      
   4. Click on the link below to see a map of earthquakes larger than magnitude 5.0 on the Richter scale in California since 1800 (provided by the California Geologic Survey).
      

      Earthquakes stronger than magnitude 5.0 in California since 1800:
      (http://www.conservation.ca.gov/cgs/rghm/quakes/PublishingImages/statewide_view_gif.gif)
      

      Based on this map and on the previous map, would you say that the pattern of the last week's worth of activity is representative of the pattern of medium to large sized earthquakes in California historically?
      
   
   
   
2. Click on the link below to see a map of the global distribution of earthquakes from 1975-1995 (provided by the USGS's National Earthquake Information Center). The colored dots represent the locations of earthquakes. (At this point, treat all colos the same.)
   

   Global distribution of earthquakes from 1975-1995:
   (http://neic.usgs.gov/neis/general/seismicity/world.html)
   
   

   Based on this map, how would you describe the global distribution of earthquakes? Is the pattern relatively random, or is there some systematic organization? If the patterns appear organized, describe what pattern of organization you see.