Friday, October 17, 2014

Earthquake Maps Available from Ball State University Libraries

This Day in History:  Earthquake Maps Available from Ball State University Libraries

On October 17, 1989, at 5:04 p.m. local time, an earthquake struck a section of the San Andreas Fault System near the San Francisco Bay area.  This was the first earthquake ever to be broadcast live on national television since the San Francisco Giants were playing the Oakland A’s in Game 3 of the World Series at Candlestick Park.  The earthquake was later named the “Loma Prieta” earthquake for the southern Santa Cruz Mountains. 

The Ball State University Libraries GIS Research and Map Collection (GRMC) includes a substantial collection of maps and other resources documenting earthquakes.  The United States Geological Survey (USGS) has published a number of maps showing global seismicity and more detailed maps of individual states like California, Utah, and Alaska.  Another map by the USGS shows three centuries of earthquakes in the central United States—from 1699 to 2002. 

The map above (top, click to enlarge) is a USGS LandSat image of earthquakes and faults in the San Francisco Bay area.  The yellow circles depict the size of earthquakes occurring in the region.  The Loma Prieta earthquake epicenter is the largest circle in the mountain area northeast of Santa Cruz.

Another map (above) of San Francisco published by the USGS shows the actual ground-shaking effects around the city.  Using remote-sensing, the map shows areas of the city built on either sand (gold color on map), bedrock (blue), serpentinite (green), or bay mud and fill (red).  According to the map, the same areas of the city were damaged in the 1906 and 1989 earthquakes:  “These districts are repeatedly damaged because they are built on soft ground that amplifies the shaking in earthquakes.  Structures built on harder ground, such as bedrock, suffer less damage.” 

Earthquake digital data on CD-ROMs is also available from the GRMC and circulates just like maps in the collection.  Maps circulate for two weeks or longer.

For more information, please visit the GRMC Monday through Friday from 8:00 to 5:00 p.m. or call 765-285-1097.

No comments: