Earthquakes in Southern California

Imperial County Services Building Before and After 1979 Earthquake

Imperial County Services Building before (left) and after earthquake (right) showing support pillar failure at the east end of building. This 6-story reinforced concrete frame and shear wall structure completed in 1971 at a construction cost of $1.87 million, was designed to be earthquake resistant. However, during the quake the concrete at the base of the support columns was shattered and the vertical reinforced bars were severely bent allowing the east portion of the building to sag about 30 cm. Replacement costs were estimated at $7 million. Photo Credits: Bay Area Regional Earthquake Preparedness Project, and U.S. Geological Survey

Earth Cracks near El Centro from 1979 Earthquake

Earth cracks near El Centro. Such cracks caused the breakage of underground water pipes in many places; however utilities were interrupted for only a short period of time. Photo Credit: University of Colorado

Sand Boil Near El Centro, 1979

A sand boil near El Centro provides graphic evidence of liquefaction. Such boils were found especially along the southern extent of the Imperial Fault. Liquefaction occurs when earthquake ground shaking distorts the granular structure of the ground causing some loosely packed groups of grains to collapse together. Each collapse transfers pressure from the grain groups to the water. When the pore-water pressures reach a critical level, the granular material suddenly behaves as a liquid rather than a solid and liquefaction has taken place. Photo Credit: G. Reagor, U.S. Geological Survey

Merchandise on Floor After 1979 Imperial Valley Earthquake

Merchandise that fell from shelves in Brawley Drug Store. Aftershocks continued for several months, and several shocks were strong enough to knock merchandise from shelves and to break display windows in the area. Photo Credit: G. Reagor, U.S. Geological Survey

Fallen Porch after 1979 Imperial Valley Earthquake

Fallen porch on 200 block of "G" Street in Brawley. Several homes were damaged in this block. Most of the residential damage was to chimneys. Photo Credit: G. Reagor, U.S. Geological Survey

Fault Trace across Lettuce Field, 1979 Imperial Valley Earthquake

A fault trace crosses a cultivated field near El Centro. The surface rupture on the Imperial Fault extended from about 2.5 miles (4 km) north of the International Border to about 2.5 miles south of Brawley. Maximum lateral displacement was about 22 inches (55 cm) in Heer Dunes and the maximum vertical displacement was 7.5 inches (19 cm) southeast of Brawley. Photo Credit: University of Colorado

Damage to Theater at Brawley, 1979 Imperial Valley Earthquake

The unreinforced brick wall at the Brawley Theater collapsed. Most of the building damage in the business district of Brawley occurred between the 500 and 900 blocks. Unreinforced brick structures are particularly vulnerable to earth shaking. Photo Credit: Bay Area Regional Earthquake Preparedness Project

Damage to Adobe Building in Westmorland, CA, 1981

Earthquake of April 26, 1981, Westmorland, California.
Epicenter: 33.1 deg N, 115.6 deg W. Magnitude 6.3. Damage $1-$3 million. Subsidence was reported on several rural roads in the area. Liquefaction caused scores of mudpots, and oozing soil in nearby fields. One country road west of Westmorland collapsed, producing a 2-foot drop-off. In rural areas, unreinforced, concrete-lined irrigation canals were broken.

View of partially collapsed adobe building in Westmorland. Seventy percent of the 900 homes in Westmorland were damaged. Most, like this structure, were constructed of adobe and/or brick. Photo Credit: Bay Area Regional

Collapsed Building in 1981 Westmorland, CA Earthquake

Earthquake of April 26, 1981, Westmorland, California.
Epicenter: 33.1 deg N, 115.6 deg W. Magnitude 6.3. Damage $1-$3 million. Subsidence was reported on several rural roads in the area. Liquefaction caused scores of mudpots, and oozing soil in nearby fields. One country road west of Westmorland collapsed, producing a 2-foot drop-off. In rural areas, unreinforced, concrete-lined irrigation canals were broken.

View of a two story building partially collapsed in earthquake. Note the undamaged one story building on the left. Twelve buildings were severely damaged and an additional 30 sustained minor damage. City officials ordered the demolition of ten downtown buildings that were damaged beyond repair. Photo Credit: Bay Area Regional Earthquake Preparedness Project

Porch Damage, 1986 Palm Springs, CA Earthquake

Earthquake of July 8, 1986, Palm Springs, California.
Epicenter: 34.0 deg N, 116.6 deg W. Magnitude 6.0. Damage: $4.5 million.

This porch was separated from the trailer and damaged by the quake. Trailers incurred more structural damage than any other type of structure in this earthquake. Photo Credit: Bay Area Regional Earthquake Preparedness Project

Rockfall on Highway after 1986 Palm Springs Earthquake

Earthquake of July 8, 1986, Palm Springs, California.
Epicenter: 34.0 deg N, 116.6 deg W. Magnitude 6.0. Damage: $4.5 million.

This rockfall on the highway is just one of many landslides that occurred in the Palm Springs, California, area. Such rockfalls can temporarily block roads and highways and hinder the movement of emergency vehicles. Photo Credit: Bay Area Regional Earthquake Preparedness Project

Damage to Display Window, 1986 Palm Springs Earthquake

Earthquake of July 8, 1986, Palm Springs, California.
Epicenter: 34.0 deg N, 116.6 deg W. Magnitude 6.0. Damage: $4.5 million.

A broken display window in a store in downtown Palm Springs. Display windows often break in moderate magnitude earthquakes since the window occupies a large structurally unsupported area of the building subject to torsional forces. Photo Credit: Bay Area Regional Earthquake Preparedness Project

Collapsed Concrete Block Fence Due to 1986 Palm Springs, CA Earthquake

Earthquake of July 8, 1986, Palm Springs, California.
Epicenter: 34.0 deg N, 116.6 deg W. Magnitude 6.0. Damage: $4.5 million.

This concrete block fence near a trailer park collapsed during the quake. Such fence failures were common. Note bent reinforcing rod. Photo Credit: Bay Area Regional Earthquake Preparedness Project

Two Views of Auditorium Showing Damage of 1987 Whittier, CA Earthquake

Earthquake of October 1, 1987, Whittier Narrows, California.
Epicenter: 34.0 deg N, 118.1 deg W. Magnitude: 5.9. Damage: $358 million. Eight deaths. The fault which ruptured was located about 11 km below the surface, and 20 km east of downtown Los Angeles. The fault was an extension of the previously identified Whittier Fault. Severe damage was confined mainly to communities of Los Angeles and near the epicenter.

Left: San Gabriel Civic Auditorium after main shock and before large aftershock. Note cracks near bell tower. Right: The same structure showing damage that occurred during large aftershock. The bell tower that was weakened by the main shock has fallen, and the exterior of building is damaged. Photo Credit: G. Reagor, U.S. Geological Survey

Partial Collapse of Store in 1987 Whittier, CA Earthquake

Earthquake of October 1, 1987, Whittier Narrows, California.
Epicenter: 34.0 deg N, 118.1 deg W. Magnitude: 5.9. Damage: $358 million. Eight deaths. The fault which ruptured was located about 11 km below the surface, and 20 km east of downtown Los Angeles. The fault was an extension of the previously identified Whittier Fault. Severe damage was confined mainly to communities of Los Angeles and near the epicenter.

Partial collapse of the back wall of thrift store located on Main Street between Fifth and Sixth Streets in Alhambra. Falling bricks crushed cars parked in the street. Photo Credit: G. Reagor, U.S. Geological Survey

Shift of Apartment Building in 1987 Whittier, CA Earthquake

Earthquake of October 1, 1987, Whittier Narrows, California.
Epicenter: 34.0 deg N, 118.1 deg W. Magnitude: 5.9. Damage: $358 million. Eight deaths. The fault which ruptured was located about 11 km below the surface, and 20 km east of downtown Los Angeles. The fault was an extension of the previously identified Whittier Fault. Severe damage was confined mainly to communities of Los Angeles and near the epicenter.

The Garvey West Apartment building in Monterey Park at Monterey Pass Road in Garvey shifted about 10 inches to the east on its foundation. Shown here is the southeast corner of the building. Photo Credit: G. Reagor, U.S. Geological Survey

Partial Collapse of Parking Garage, Whittier, CA, 1987 Earthquake

Earthquake of October 1, 1987, Whittier Narrows, California.
Epicenter: 34.0 deg N, 118.1 deg W. Magnitude: 5.9. Damage: $358 million. Eight deaths. The fault which ruptured was located about 11 km below the surface, and 20 km east of downtown Los Angeles. The fault was an extension of the previously identified Whittier Fault. Severe damage was confined mainly to communities of Los Angeles and near the epicenter.

Partial collapse of the May Company's three-level parking garage at Quad Shopping Mall in Whittier. The structure, built in 1965, is located at the corner of Whittier Blvd. and Painter Ave. Photo Credit: G. Reagor, U.S. Geological Survey

Exterior View of Damaged Residence, Whittier, CA 1987 Earthquake

Earthquake of October 1, 1987, Whittier Narrows, California.
Epicenter: 34.0 deg N, 118.1 deg W. Magnitude: 5.9. Damage: $358 million. Eight deaths. The fault which ruptured was located about 11 km below the surface, and 20 km east of downtown Los Angeles. The fault was an extension of the previously identified Whittier Fault. Severe damage was confined mainly to communities of Los Angeles and near the epicenter.

Exterior view (left) of badly damaged brick residence in the 5000 block of Bright Street in North Whittier. Interior view on right shows cracks extending through the outside wall of structure. Photo Credit: G. Reagor, U.S. Geological Survey

Interior View of Damaged Residence, Whittier, CA 1987 Earthquake

Earthquake of October 1, 1987, Whittier Narrows, California.
Epicenter: 34.0 deg N, 118.1 deg W. Magnitude: 5.9. Damage: $358 million. Eight deaths. The fault which ruptured was located about 11 km below the surface, and 20 km east of downtown Los Angeles. The fault was an extension of the previously identified Whittier Fault. Severe damage was confined mainly to communities of Los Angeles and near the epicenter.

Collapse of chimney through roof of above residence and onto bed of four-year old boy who was rescued and hospitalized with broken collar bone. Photo Credit: G. Reagor, U.S. Geological Survey

Collapse of Wall of Store in 1987 Whittier, CA Earthquake

Earthquake of October 1, 1987, Whittier Narrows, California.
Epicenter: 34.0 deg N, 118.1 deg W. Magnitude: 5.9. Damage: $358 million. Eight deaths. The fault which ruptured was located about 11 km below the surface, and 20 km east of downtown Los Angeles. The fault was an extension of the previously identified Whittier Fault. Severe damage was confined mainly to communities of Los Angeles and near the epicenter.

Collapse of wall of second story of Art's Jewelry and Loan establishment on Greenleaf Avenue in "Uptown" Whittier. This older section in north Whittier sustained serious damage. At least 200 residences and 30 businesses were badly damaged and most of the severe damage was to structures built before 1930. Photo Credit: G. Reagor, U.S. Geological Survey