Loma Prieta, California, Earthquake October 17, 1989. Oakland. Support column failure and collapsed upper deck on the Cypress viaduct of Interstate 880. Slide III-5, U.S. Geological Survey Open-File Report 90-547.
(Photo I.D. whg00003)

Historically, the Earth quakes in October...

On October 17, 1989, at 5:04 pm local time, a 7.1 surface-wave magnitude earthquake shook San Francisco, Oakland, and the surrounding peninsula for 15 seconds. The epicenter was located south-southwest of Loma Prieta Peak in the Santa Cruz Mountains’ Forest of Nisene Marks State Park. Much of this area had been rebuilt on top of the reclaimed land of the rubble from the 1906 San Francisco earthquake, leaving it very unstable. The Loma Prieta quake caused liquefaction of the underlying soil, resulting in extensive property damage throughout the region estimated at $6 billion.

The earthquake started during the evening commuter rush hour and collapsed part of the San Francisco-Oakland Bay Bridge and the Cypress Street Viaduct on the Nimitz Freeway (Interstate 880), which had the highest concentration of victims at this location with 42 deaths. Luckily enough, many people had left work early due to the two Major League Baseball teams, the Oakland Athletics and the San Francisco Giants, playing the third game of the 1989 World Series and this is speculated to have saved lives. The final death toll was 66, along with 3,757 reported injuries.

The 1989 Loma Prieta earthquake was the one of the largest quakes to occur on the San Andreas Fault, second only to the great San Francisco earthquake of 1906

For more information regarding this earthquake and others, visit the following links:

USGS DDS-29 “The October 17, 1989, Loma Prieta, California, Earthquake”
http://pubs.usgs.gov/dds/dds-29/

USGS Earthquake Hazards Program
http://neic.usgs.gov/neis/eq_depot/usa/1989_10_18.html

“This Dynamic Planet”
World Map of Volcanoes, Earthquakes, Impact Craters, and Plate Tectonics
http://www.minerals.si.edu/tdpmap/index.htm