Images

Seismicity of the United States 1975-1995. Seismicity refers to the geographic and historical distribution of earthquakes.

This ShakeMap of the January 17, 1994 M6.7 Northridge earthquake shaking shows the result of rupture directivity toward the north.

Collection of USGS still images taken after the January 17, 1994 Northridge earthquake highlighting the damage to buildings and infrastructure.

1992 M7.2 Landers, California earthquake slip model

A slip model is a kinematic model that describes the amount, distribution, and timing of slip associated with an earthquake.

The Emerson fault, one of the segments that ruptured in the M7.2 1992 Landers, Calfornia earthquake. 

An automobile lies crushed under the third story of this apartment building in the Marina District. The ground levels are no longer visible because of structural failure and sinking due to liquefaction.

Cross-Sections of Seismicity Along the San Andreas Fault from "Lessons learned from the Loma Prieta, California, earthquake of October 17, 1989"

A downtown building at the corner of Alice and 13th Streets lost part of its unreinforced facade and brick masonry.

The segments of the San Andreas Fault, and the probability for strong shaking in the next 30 years on each segment. 

Oblique aerial view of San Andreas Fault (between white arrows) in southeastern Coachella Valley, near Red Canyon; view to the west.

Charles Richter, inventor of the Richter Scale.

Seismology is the study of earthquakes and the structure of the earth, by both naturally and artificially generated seismic waves.

During the first week of April a different type of seismic signature was showing up on seismograms from Mount St. Helens. On April 1 the first weak harmonic tremor was detected. Stronger bursts of harmonic tremor were recorded on the 2nd. The seismogram above is an example of harmonic tremor recorded at seismic station RAN on April 2.

The nine generalized couples of the seismic moment tensor. Modified after Aki and Richards (1980).

Photo of deformed rock. Deformation is a change in the original shape of a material. When we are talking about earthquakes, deformation is due to stress and strain.

The Richter magnitude scale was developed in 1935 by Charles F. Richter of the California Institute of Technology as a mathematical device to compare the size of earthquakes. The magnitude of an earthquake is determined from the logarithm of the amplitude of waves recorded by seismographs.

Photo of 1995 landslide in La Conchita, California. A landslide is a movement of surface material down a slope. 

1906 earthquake damage to home on Howard and 17th Streets in San Francisco. Liquefaction, the phenomenon of saturated soils losing their stiffness and strength during shaking, caused structures to tilt and collapse.

Strong shaking during the 1868 Hayward Fault earthquake caused the second story of the Alameda County Courthouse in San Leandro to collapse (photo courtesy of the Bancroft Library, University of California). The inset photo shows the courthouse before the quake

Artist D.V. Rogers stomps on one of the geophones surrounding the shake table to trigger it.

Full view of the ground with the San Andreas fault running through the middle of the image. A 30 foot steam offset from the 1857 earthquake can be seen near the right edge of the image.

Photo showing the kite that is suspending the camera over the San Andreas Fault.