The San Andreas Fault is a continental transform fault that extends roughly 1,200 kilometers (750 mi) through California. It forms the tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip (horizontal). The fault divides into three segments, each with different characteristics and a different degree of earthquake risk. The slip rate along the fault ranges from 20 to 35 mm /yr.
The Los Angeles metropolitan area, also known as Metropolitan Los Angeles or the Southland, is the 30th largest metropolitan area in the world and the second-largest metropolitan area in the United States. It is the 3rd largest city by GDP in the world with a $1 trillion+ economy. It is entirely in the southern portion of the U.S. state of California. The tallest building in the Los Angeles metropolitan area is the Wilshire Grand Center at 1,100 feet in Downtown Los Angeles.
The Los Angeles Basin is a sedimentary basin located in southern California, in a region known as the Peninsular Ranges. The basin is also connected to an anomalous group of east-west trending chains of mountains collectively known as the California Transverse Ranges. The present basin is a coastal lowland area, whose floor is marked by elongate low ridges and groups of hills that is located on the edge of the Pacific plate. The Los Angeles Basin, along with the Santa Barbara Channel, the Ventura Basin, the San Fernando Valley, and the San Gabriel Basin, lies within the greater southern California region. On the north, northeast, and east, the lowland basin is bound by the Santa Monica Mountains and Puente, Elysian, Repetto hills. To the southeast, the basin is bordered by the Santa Ana mountains and the San Joaquin Hills. The western boundary of the basin is marked by the Continental Borderland and is part of the onshore portion. The California borderland is characterized by north-west trending offshore ridges and basins. The Los Angeles Basin is notable for its great structural relief and complexity in relation to its geologic youth and small size for its prolific oil production. Yerkes et al. identify 5 major stages of the basin's evolution that begins in the Upper Cretaceous and ends in the Pleistocene. This basin can be classified as an irregular pull-apart basin accompanied by rotational tectonics during the post-early Miocene.
The 1987 Whittier Narrows earthquake occurred in the southern San Gabriel Valley and surrounding communities of southern California at 7:42 a.m. PDT on October 1. The moderate 5.9 magnitude blind thrust earthquake was centered several miles north of Whittier in the town of Rosemead, had a relatively shallow depth, and was felt throughout southern California and southern Nevada. Many homes and businesses were affected, along with roadway disruptions, mainly in Los Angeles and Orange counties. Damage estimates ranged from $213–358 million, with 200 injuries, three directly-related deaths, and five additional fatalities that were associated with the event.
The California Earthquake Prediction Evaluation Council (CEPEC) is a committee of earthquake experts that reviews potentially credible earthquake predictions and forecasts. Its purpose is to advise the Governor of California via the California Office of Emergency Services.
The San Jacinto Fault Zone (SJFZ) is a major strike-slip fault zone that runs through San Bernardino, Riverside, San Diego, and Imperial Counties in Southern California. The SJFZ is a component of the larger San Andreas transform system and is considered to be the most seismically active fault zone in the area. Together they relieve the majority of the stress between the Pacific and North American tectonic plates.
Crafton is an unincorporated community in San Bernardino County, California, United States, located east of Redlands, south of Mentone and west of Yucaipa, California.
The Yorba Linda Fault or Yorba Linda Trend is a fault system that extends from northeast Yorba Linda, California to the southeastern portion of the Chino Hills and Chino Hills (city), in Orange County, California.
The Hosgri Fault is an offshore fault zone located near the Central Coast of California in San Luis Obispo County. The main fault stretches for about 87 miles (140 km), and is located nearest to the coastal communities of Cambria, San Simeon, Morro Bay, Baywood Park-Los Osos and Avila Beach. The fault system is some 260 mi (420 km) long, and is a right-lateral strand of the San Andreas Fault system.
The Brea-Olinda Oil Field is a large oil field in northern Orange County and Los Angeles County, California, along the southern edge of the Puente Hills, about four miles (6 km) northeast of Fullerton, and adjacent to the city of Brea. Discovered in 1880, the field is the sixteenth largest in California by cumulative production, and was the first of California's largest 50 oil fields to be found. It has produced over 412 million barrels of oil in the 130 years since it was first drilled, and retains approximately 19 million barrels in reserve recoverable with current technology. As of the beginning of 2009, 475 wells remained active on the field, operated by several independent oil companies, including Linn Energy, BreitBurn Energy Partners L.P., Cooper & Brain, and Thompson Energy.
The 1940 El Centro earthquake occurred at 21:35 Pacific Standard Time on May 18 in the Imperial Valley in southeastern Southern California near the international border of the United States and Mexico. It had a moment magnitude of 6.9 and a maximum perceived intensity of X (Extreme) on the Mercalli intensity scale. It was the first major earthquake to be recorded by a strong-motion seismograph located next to a fault rupture. The earthquake was characterized as a typical moderate-sized destructive event with a complex energy release signature. It was the strongest recorded earthquake to hit the Imperial Valley, and caused widespread damage to irrigation systems and led to the deaths of nine people.
The Elsinore Trough is a graben rift valley in Riverside County, southern California. It is created by the Elsinore Fault Zone.
The Perris Block is the central block of three major fault-bounded blocks of the northern part of the Peninsular Ranges. The Perris Block lies between the Santa Ana Block to the west and the San Jacinto Block to the east. The Perris Block, was named by Walter A. English in 1925 for the city of Perris, located near the center of the block.
Wolf Valley is a graben rift valley in the Elsinore Trough, in western Riverside County, California.
The 2019 Ridgecrest earthquakes of July 4 and 5 occurred north and northeast of the town of Ridgecrest, California and west of Searles Valley, California. They included three main shocks of Mw magnitudes 6.4, 5.4, and 7.1, and many perceptible aftershocks, mainly within the area of the Naval Air Weapons Station China Lake. The first main shock occurred on July 4 at 10:33 a.m. PDT, approximately 18 km (11.2 mi) ENE of Ridgecrest, and 13 km (8.1 mi) WSW of Trona, on a previously unnoticed NE-SW trending fault where it intersects the NW-SE trending Little Lake Fault Zone. This quake was preceded by several smaller earthquakes, and was followed by more than 1,400 detected aftershocks. The M 5.4 and M 7.1 quakes struck on July 5 at 4:08 a.m. and 8:19 p.m. PDT approximately 10 km (6 miles) to the northwest. The latter, now considered the mainshock, was the most powerful earthquake to occur in the state in 20 years. Subsequent aftershocks extended approximately 50 km (~30 miles) along the Little Lake Fault Zone.
