TIME: January 17, 1994 / 4:30:55 am PST
LOCATION: 20 miles west-northwest of Los Angeles
At 4:30 am, on January 17, 1994, residents of the greater Los Angeles area were rudely awakened by the strong shaking of the Northridge earthquake. This was the first earthquake to strike directly under an urban area of the United States since the 1933 Long Beach earthquake.
The earthquake occurred on a blind thrust fault, and produced the strongest ground motions ever instrumentally recorded in an urban setting in North America. Damage was wide-spread, sections of major freeways collapsed, parking structures and office buildings collapsed, and numerous apartment buildings suffered irreparable damage. Damage to wood-frame apartment houses was very widespread in the San Fernando Valley and Santa Monica areas, especially to structures with "soft" first floor or lower-level parking garages. The high accelerations, both vertical and horizontal, lifted structures off of their foundations and/or shifted walls laterally.
LOMA PRIETA EARTHQUAKE
TIME: October 17, 1989 / 5:04 pm PST
LOCATION: 10 miles northeast of the city of Santa Cruz, California,
The Loma Prieta earthquake occurred in the greater San Francisco Bay Area in California. It is popularly nicknamed the World Series Quake because it occurred during the World Series, which happened to match up the Bay Area's two Major League Baseball teams. The earthquake lasted for 15 seconds Portion of the Cypress Street Viaduct, Interstate 880, in Oakland collapsed.
This was a major earthquake which caused severe damage as far as 70 miles away; most notably in San Francisco, Oakland, the San Francisco Peninsula, and in areas closer to the epicenter in the communities of Santa Cruz, the Monterey Bay, Watsonville, and Los Gatos. There were at least 63 deaths (some say 66) and 3,757 injuries as a result of this earthquake. The quake also caused an estimated $6 billion in property damage, the costliest natural disaster in U.S. history at the time. It was the largest earthquake to occur on the San Andreas Fault since the great 1906 San Francisco earthquake.
AN FERNANDO EARTHQUAKE
TIME: February 9, 1971 / 6:01 am PST
LOCATION: 34° 24.67' N, 118° 24.04' W
Also known as the Sylmar Earthquake, this earthquake occurred on the San Fernando fault zone, a zone of thrust faulting which broke the surface in the Sylmar-San Fernando Area. The total surface rupture was roughly 19 km (12 miles) long. The maximum slip was up to 2 meters (6 feet). The earthquake caused over $500 million in property damage and 65 deaths. Most of the deaths occurred when the Veteran's Administration Hospital collapsed. Several other hospitals, including the Olive View Community Hospital in Sylmar suffered severe damage. Newly constructed freeway overpasses also collapsed, in damage scenes similar to those which occurred 23 years later in the 1994 Northridge Earthquake. Loss of life could have been much greater had the earthquake struck at a busier time of day.
KERN COUNTY EARTHQUAKE
TIME: July 21, 1952 / 4:52 am, PDT
LOCATION: 23 miles south of Bakersfield
The largest earthquake in southern California since the Fort Tejon earthquake of 1857 and the Owens Valley earthquake of 1872, the Kern County earthquake of 1952 caused immense and widespread damage. The quake occurred on the White Wolf fault, a reverse fault (with some left-lateral component of slip) north of the intersection of the Garlock and San Andreas faults. The area shaken by this quake was impressively large. It was felt in Reno, Nevada, and required a construction effort in Las Vegas to realign structural steel. In San Francisco, it was felt mainly by people on the upper floors of tall buildings. Power outages occurred in Los Angeles, along with minor building damage. It was felt in San Diego as well, and even damaged one building there! At Owens Lake, about 200 kilometers away, the shaking broke a pipeline and disturbed salt beds, causing damage to a mining operation. The Kern County earthquake claimed 12 lives, was responsible for at least 18 injuries, and caused at least $50 million in property damage. This quake and its aftershocks (at least 20 were of magnitude 5.0 or greater) were responsible for damaging hundreds of buildings in the Kern County area, at least 100 of which had to be torn down. It devastated a section of the Southern Pacific Railroad line near Bear Mountain. It wreaked havoc on agriculture in the Arvin area, where the land has been reclaimed from the Kern River Delta, creating conditions which amplify the shaking of an earthquake. Slumping and surface rupture caused irrigation breaks and subsurface movement disturbed well output. Major relevelling had to be done in many places.
THE GREAT SAN FRANSISCO EARTHQUAKE 1906
TIME: April 18, 1906/ 5:12 am PST
LOCATION: 2 miles offshore from San Fransisco
The Great San Francisco earthquake of 1906 struck San Francisco and the coast of northern California. It ruptured along the San Andreas Fault both northward and southward for a total length of 296 miles. Shaking was felt from Oregon to Los Angeles, and inland as far as central Nevada. The earthquake and resulting fire would be remembered as one of the worst natural disasters in the history of the United States, comparable in devastation to the Galveston Hurricane of 1900 and Hurricane Katrina in 2005. This death toll has been revised to today's conservative estimate of at least 3000; some estimates have put it as high as 6000. Between 225,000 and 300,000 people were left homeless out of a population of about 400,000. Over 80% of the city was destroyed by the earthquake and fire. The 1908 Lawson Report, a study of the 1906 quake, showed that the very same San Andreas Fault which had caused the disaster in San Francisco ran close to Los Angeles as well.