San Andreas fault

San Andreas fault
/san" an dray"euhs/, Geol.
an active strike-slip fault in W United States, extending from San Francisco to S California and forming the on-land portion of the western margin of the North American Plate.
[after San Andreas Lake, located in the rift, in San Mateo County]

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Zone of transform faults at the boundary between two tectonic plates in the western U.S. The fault runs along the coast of northern California for 650 mi (1,050 km) and passes seaward in the vicinity of San Francisco.

Movement along the fault is characterized by frequent earthquakes, including the major San Francisco quake of 1906, when parts of the fault line moved as much as 21 ft (6.4 m), and the less serious earthquake of 1989.

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 major fracture of the Earth's crust in extreme western North America. The fault trends northwestward for more than 800 miles (1,300 km) from the northern end of the Gulf of California (California, Gulf of) through western California, U.S., passing seaward into the Pacific Ocean in the vicinity of San Francisco. Tectonic movement along the fault has been associated with occasional large earthquakes originating near the surface along its path, including a disastrous quake in San Francisco in 1906, a less serious event there in 1989, and a strong and destructive quake centred in the Los Angeles suburb of Northridge in 1994 that occurred along one of the San Andreas's larger secondary faults.

      According to the theory of plate tectonics, the San Andreas Fault represents the transform (strike-slip) boundary between two major plates of the Earth's crust: the Northern Pacific to the south and west and the North American to the north and east. The Northern Pacific plate is sliding laterally past the North American plate in a northerly direction, and hence the San Andreas is classified as a strike-slip fault. The movement of the plates relative to each other has been about 1 cm (0.4 inch) per year over geologic time, though the annual rate of movement has been 4 to 6 cm (1.6 to 2.4 inches) per year since the early 20th century. Parts of the fault line moved as much as 6.4 metres (21 feet) during the 1906 earthquake.

      The great majority of California's population lives in the vicinity of the San Andreas Fault. Some cities, towns, housing developments, and roads are actually built on it, and a tunnel of the San Francisco Bay Area Rapid Transit System (BART) is bored right through the fault zone. Measures taken to offset the danger from earthquakes include reinforcing roads and bridges to withstand tremors and constructing buildings to absorb seismic shocks.

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Universalium. 2010.

Look at other dictionaries:

  • San Andreas Fault —   [sæn ændreɪs fɔːlt, englisch], San Andreas Störung, tektonische Verwerfungszone in Kalifornien, erstreckt sich vom Nordende des Golfs von Kalifornien in Nordwestrichtung durch das Imperial Valley, durch die Coloradowüste östlich von Los Angeles …   Universal-Lexikon

  • San Andreas fault — ☆ San Andreas fault [san an drā′əs ] [after San Andreas valley, through which the fault runs: orig. Sp, San Andrés, St. Andrew] active fault in the earth s crust extending northwest from S California for about 600 miles (966 km) …   English World dictionary

  • San Andreas fault — San An|dre|as fault the San Andreas fault a crack in the Earth s surface which goes from the north to the south of California in the western US. The large areas of rock on either side of this crack are slowly moving in different directions, and… …   Dictionary of contemporary English

  • San Andreas Fault — The San Andreas Fault is a geologic transform fault that runs a length of roughly 800 miles (1,300 km) through California in the United States. The fault s motion is right lateral strike slip (horizontal motion). It forms the tectonic boundary… …   Wikipedia

  • San Andreas Fault — noun a major geological fault in California; runs from San Diego to San Francisco; the source of serious earthquakes • Instance Hypernyms: ↑fault, ↑faulting, ↑geological fault, ↑shift, ↑fracture, ↑break • Part Holonyms: ↑ …   Useful english dictionary

  • San Andreas fault — noun One of the geographical faults running through San Andreas, California. The southern California portion of the coastline is a major transform fault, commonly known as the San Andreas Fault …   Wiktionary

  • San Andreas Fault — Sp Šveñtojo Andriẽjaus sprūdis Ap San Andreas Fault L tektoninių lūžių zona JAV (Kalifornija) …   Pasaulio vietovardžiai. Internetinė duomenų bazė

  • San Andreas fault — San′ An•dre′as fault′ [[t]ˈsæn ænˈdreɪ əs[/t]] n. gel an active geological fault in the western U.S., extending from San Francisco to S California • Etymology: after San Andreas Lake, located in the rift, in San Mateo County …   From formal English to slang

  • San Andreas Fault — /sæn ænˈdreɪəs/ (say san an drayuhs) noun a major fracture in the earth s crust running through western California; site of many tremors and earthquakes, including the San Francisco earthquake in 1906. About 960 km long …   Australian-English dictionary

  • San Andreas Fault — geographical name zone of faults California extending from N coast toward head of Gulf of California …   New Collegiate Dictionary

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