Additional Information

Additional Information about the Earthquakes featured in the Exhibit

All of the earthquakes featured had an average magnitude of 6.48

All of the earthquakes caused structural damages estimated above 39 million U.S. dollars.

Every earthquake, with the exception of the 1933 Long Beach earthquake, occurred early in morning between the hours of 4:30 am – 7:45 am.

The 1971 San Fernando, 1987 Whitter-Narrows, and 1994 Northridge earthquakes were blind thrust fault events.

Blind thrust faults are faults that are buried deeper underground, and do not break or show signs of activity on the surface when weak points in the layers of the earth’s crust slide against each other at a vertical angle.  

The 1925 Santa Barbara and 1933 Long Beach earthquakes were strike-slip fault events. Both earthquakes had epicenters located near or offshore in the Pacific Ocean.

Strike-slip faults are faults that are vertical (or nearly vertical) fractures in the earth’s crust where during an earthquake the layers and surface of the earth mostly move horizontally. The tectonic plates strike and slip against each other in opposite and parallel movements.

Besides the major San Andres Fault Line, Metropolitan Los Angeles County is sandwiched between three slightly smaller but major thrust faults; the Compton, Puente Hills, and Sierra Madre fault lines. Los Angeles is also centered in a complex cluster of various fault lines that contribute to the city’s gradual movement north and the increased elevation of the San Gabriel Mountains. The crust underlying Los Angeles is cut by thrust faults, strike-slip faults, like the San Andreas Fault, and other strike-slip or blind thrust faults sub-parallel and perpendicular to the Los Angeles basin.  These faults all take part in accommodating the gradual “north-south squeeze.”


For more information on earthquakes refer to these resources:

California Institute of Technology: Southern California Earthquake Data Center:
Cal Tech Seismological Laboratory:
Southern California Earthquake Center:
United States Geological Survey Website:


Discover what the Department of History at Cal State University, Los Angeles has to offer at:

The Ground Beneath Our Feet: A Hundred Years of Earthquakes Digital Exhibit is also available at: