View of the San Andreas Fault on the Carrizo Plain in central California, 35°07'N, 119°39'W

Aerial photo of the San Andreas Fault in the Carrizo Plain

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 Carrizo Plain is a large enclosed plain approximately 50 miles (80 km long and up to 15 miles (24 km across in southeastern San Luis Obispo County California ( is a US state on the West Coast of the United States, along the Pacific Ocean. The Carrizo Plain is a large enclosed plain approximately 50 miles (80 km long and up to 15 miles (24 km across in southeastern San Luis Obispo County A transform fault is a fault which runs along the boundary of a Tectonic plate. California ( is a US state on the West Coast of the United States, along the Pacific Ocean. The United States of America —commonly referred to as the The fault's motion is right-lateral strike-slip (horizontal motion). This article is about the geologic usage for human physiology usage see the articles Laterality. It forms the tectonic boundary between the Pacific Plate and the North American Plate. This article discusses the geologic usage for the philosophical or architectural usage see Architectonics ' Or see Plate tectonics. The Pacific Plate is an oceanic Tectonic plate beneath the Pacific Ocean. The North American Plate is a Tectonic plate covering most of North America, Greenland and part of Siberia.

The fault was first identified in Northern California by UC Berkeley geology professor Andrew Lawson in 1895 and named by him after a small lake which lies in a linear valley formed by the fault just south of San Francisco, the Laguna de San Andreas. Northern California is the northern portion of the US state of California. The University of California Berkeley (also referred to as Cal, Berkeley and UC Berkeley) is a major research university located in Berkeley Andrew Cowper Lawson (1861-1952 was a professor of geology at the University of California Berkeley. San Andreas Lake (from Spanish Laguna de San Andreas) is the name of an upland lake on the San Francisco Peninsula south of the city of San Francisco Following the 1906 San Francisco Earthquake, it was Lawson who also discovered that the San Andreas Fault stretched well southward into Southern California. Southern California, or So Cal, is defined as the southern portion of the U

Southern, central, and northern segments

The San Andreas Fault can be divided into three segments.

Map of the San Andreas Fault, showing relative motion.

The southern segment (known as the Mojave segment) begins near the Salton Sea at the northern terminus of the East Pacific Rise and runs northward before it begins a slow bend to the west where it meets the San Bernardino Mountains. For the indigenous American tribe see Mohave. The Mojave Desert (moʊˈhɑːvi or /məˈhɑːvi/ ( Hayikwiir Mat'aar in Mojave The Salton Sea is an inland Saline lake, occupying the lowest elevations of the Salton Sink, part of the larger Colorado Desert in Southern The East Pacific Rise is a Mid-oceanic ridge, a divergent tectonic plate boundary located along the floor of the Pacific Ocean. The San Bernardino Mountains ( Huwaaly Kwasakyav in Mojave) are a short transverse Mountain range northeast of Los Angeles in It runs along the southern base of the San Bernardino Mountains, crosses through the Cajon Pass and continues to run northwest along the northern base of the San Gabriel Mountains. At an elevation of 1277 meters (4190 ft the Cajon Pass (kəˈhoʊn is a moderate-elevation Mountain pass between the San Bernardino Mountains and the The San Gabriel Mountains are located in northern Los Angeles County and western San Bernardino County California, USA. These mountains are a result of movement along the San Andreas Fault and are commonly called the Transverse Range. The Transverse Ranges (or more accurately the Los Angeles Ranges) are a group of mountain ranges of southern California, one of the various North American Near Palmdale, a portion of the fault is easily examined as a roadcut for the Antelope Valley Freeway runs directly through it. Palmdale, the first community within the Antelope Valley to incorporate as a city (on August 24, 1962 State Route 14 is a north-south State highway largely in the Mojave Desert of the U

After crossing through Frazier Park, the fault begins to bend northwards. Frazier Park is an Unincorporated area in Kern County, California. This area is referred to as the “Big Bend” and is thought to be where the fault locks up in Southern California as the plates try to move past each other. Southern California, or So Cal, is defined as the southern portion of the U This section of the fault has an earthquake-recurrence interval of roughly 140-160 years. Northwest of Frazier Park, the fault runs through the Carrizo Plain, a long, treeless plain within which much of the fault is plainly visible. The Carrizo Plain is a large enclosed plain approximately 50 miles (80 km long and up to 15 miles (24 km across in southeastern San Luis Obispo County The Elkhorn Scarp defines the fault trace along much of its length within the plain.

The central segment of the San Andreas fault runs in a northwestern direction from Parkfield to Hollister. Parkfield is a village in Monterey County, California. As of 2007 road signs announce the population as 18 but some sources list the population as 900 Hollister is a city in and the County seat of San Benito County, California, United States. While the southern section of the fault and the parts through Parkfield experience earthquakes, the rest of the central section of the fault exhibits a phenomenon called aseismic creep. Geology, aseismic creep is measurable surface displacement along a fault in the absence of notable Earthquakes An example is along the Calaveras This term describes the fault being able to move without causing earthquakes.

Map showing the San Andreas (reds and orange) and major "sister" faults in the San Francisco Bay Area

The northern segment of the fault runs from Hollister, through the Santa Cruz Mountains, epicenter of the 1989 Loma Prieta earthquake, then on up the San Francisco Peninsula, where it was first identified by Professor Lawson in 1895, then offshore at Pacifica at Mussel Rock. The San Francisco Bay Area, commonly known as the Bay Area, or the Bay, is a geographically and ethnically diverse metropolitan region that surrounds the The Santa Cruz Mountains, part of the Pacific Coast Ranges, are a Mountain range in central California, United States. The Loma Prieta earthquake, also known as the Quake of '89 and the World Series Quake, was a major Earthquake that struck the San Francisco Bay The San Francisco Peninsula in California separates the San Francisco Bay from the Pacific Ocean. Pacifica is a city in San Mateo County California, on the coast of the Pacific Ocean between San Francisco and Half Moon Bay. Mussel Rock is a physical feature on the coast of San Mateo County California, offshore from the city of Daly City. This is the approximate location of the epicenter of the 1906 San Francisco earthquake. The fault returns onshore at Bolinas Lagoon just north of Stinson Beach in Marin County. Bolinas Lagoon is a tidal Estuary, approximately in area located at in the West Marin region of Marin County California, United States Stinson Beach California is an unincorporated community in Marin County, California, on the west coast of the United States. March 11, 1889 | It returns underwater through the linear trough of Tomales Bay which separates the Point Reyes Peninsula from the mainland, returning onshore at Fort Ross. Tomales Bay is a long narrow inlet of the Pacific Ocean in Marin County in northern California in the United States. Point Reyes is a prominent cape on the Pacific coast of northern California. (In this region around the San Francisco Bay Area several significant "sister faults" run more-or-less parallel, and each of these can create significantly destructive earthquakes. The San Francisco Bay Area, commonly known as the Bay Area, or the Bay, is a geographically and ethnically diverse metropolitan region that surrounds the ) From Fort Ross the northern segment continues overland, forming in part a linear valley through which the Gualala River flows. The Gualala River is a River on the northern coast of California. It goes back offshore at Point Arena. Point Arena is a small Coastal city in Mendocino County, California, United States. After that, it runs underwater along the coast until it nears Cape Mendocino, where it begins to bend to the west, terminating at the Mendocino Triple Junction. Cape Mendocino in Humboldt County California, USA is the westernmost point on the coast of California. The Mendocino Triple Junction is a geologic Triple junction where the San Andreas Fault meets the Mendocino Fault and the Cascadia subduction zone

Plate movement

Historical movement of the San Andreas Fault

All land west of the fault on the Pacific Plate is moving slowly to the northwest while all land east of the fault is moving to the southwest (relatively southeast as measured at the fault) under the influence of plate tectonics. The Pacific Plate is an oceanic Tectonic plate beneath the Pacific Ocean. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere The rate of slippage averages approximately 33-37 mm/year across California. ^[1]

The westward component of the motion of the North American Plate creates compressional forces which are expressed as uplift in the Coast Ranges. Likewise, the northwest motion of the Pacific Plate creates significant compressional forces where the North American Plate stands in its way, creating the Transverse Ranges in Southern California, and to a lesser, but still significant extent, the Santa Cruz Mountains, site of the Loma Prieta Earthquake of 1989. The Loma Prieta earthquake, also known as the Quake of '89 and the World Series Quake, was a major Earthquake that struck the San Francisco Bay

Studies of the relative motions of the Pacific and North American plates have shown that only about 75 percent of the motion can be accounted for in the movements of the San Andreas and its various branch faults. The rest of the motion has been found in an area east of the Sierra Nevada mountains called the Walker Lane or Eastern California Shear Zone. The Sierra Nevada ( Spanish for "Snowy Range" is a Mountain range located in the U The Walker Lane (also known as the Eastern California Shear Zone)is a geological trough oriented north-northwest-south-southeast roughly aligned with the border of the states The reason for this is not as yet clear, although several hypotheses have been offered and research is ongoing. One hypothesis which gained some currency following the Landers Earthquake in 1992 is that the plate boundary may be shifting eastward, away from the San Andreas to the Walker Lane.

Assuming the plate boundary does not change as hypothesized, projected motion indicates that the landmass west of the San Andreas Fault, including Los Angeles, will eventually slide past San Francisco, then continue northwestward toward the Aleutian Trench, over a period of perhaps twenty million years. The Aleutian Trench (or Aleutian Trough) is a Subduction zone and Oceanic trench which runs along the southern coastline of Alaska and the On the other hand, if the plate boundary shifts eastward, then the entire state of California would move in the same direction.

Scientific research

Research at Parkfield

Further south in central California is the small town of Parkfield, California, which lies along the San Andreas Fault. Parkfield is a village in Monterey County, California. As of 2007 road signs announce the population as 18 but some sources list the population as 900 Seismologists discovered that this section of the fault consistently produces magnitude 6. 0 earthquakes about every 22 years. Following earthquakes in 1857, 1881, 1901, 1922, 1934, and 1966, scientists predicted an earthquake to hit Parkfield in 1993. Parkfield is a village in Monterey County, California. As of 2007 road signs announce the population as 18 but some sources list the population as 900 This quake eventually struck in 2004 (see Parkfield earthquake). Parkfield Earthquake is a name given to various large Earthquakes that occurred in the vicinity of the little town of Parkfield California, in the United States Because of this frequent activity and prediction, Parkfield has become one of the most popular spots in the world to try to capture and record large earthquakes.

In 2004, work began just north of Parkfield on the San Andreas Fault Observatory at Depth (SAFOD). The San Andreas Fault Observatory at Depth ( SAFOD) is one of three components of the Earthscope Project funded by the National Science Foundation in conjunction The goal of SAFOD is to drill a hole nearly 3 kilometers into the Earth's crust and into the San Andreas Fault. An array of sensors will be installed to capture and record earthquakes that happen near this area. ^[2]

The University of California study on "the next big one"

A study completed by Yuri Fialko^[3] has demonstrated that the San Andreas fault has been stressed to a level sufficient for the next "big one," as it is commonly called, that is, an earthquake of magnitude 7. The Richter magnitude scale, or more correctly local magnitude M L scale assigns a single number to quantify the amount of seismic energy released 0 or greater. The study also concluded that the risk of a large earthquake may be increasing faster than researchers had previously believed. Fialko also emphasized in his study that, while the San Andreas Fault has experienced massive earthquakes in 1857 at its central section and in 1906 at its northern segment (the great San Francisco earthquake), the southern section of the fault has not seen a similar rupture in at least 300 years.

If such an earthquake were to occur, Fialko's study stated, it would result in substantial damage to Palm Springs and a number of other cities in San Bernardino, Riverside and Imperial counties in California, and Mexicali municipality in Baja California. Palm Springs is a desert city in Riverside County, California, approximately 111 miles (177 km east of Los Angeles and 136 miles (225 km northeast of San Bernardino County is a county in the US state of California. Riverside County is a County located in the southeastern part of the U Imperial County is a County located in the Imperial Valley, in the far southeast of the U Mexicali is a municipality (municipio in the Mexican state of Baja California. Baja California (pronounced ˈbɑːhɑː kælɨˈfɔrnjə in English is the northernmost state of Mexico. Such an event would be felt throughout much of Southern California, including densely populated areas of metropolitan Los Angeles, Orange County, San Diego and Tijuana, Baja California. Southern California, or So Cal, is defined as the southern portion of the U Los Angeles (lɑˈsændʒələs los ˈaŋxeles in Spanish) is the largest City in the state of California and the American West Orange County is a county in Southern California, United States. Tijuana (ˌtiːəˈwɑːnə Spanish, ti'xwana|ti'ʍana is the largest city of the Mexican state of Baja California, situated on the U Baja California (pronounced ˈbɑːhɑː kælɨˈfɔrnjə in English is the northernmost state of Mexico.

"The information available suggests that the fault is ready for the next big earthquake but exactly when the triggering will happen and when the earthquake will occur we cannot tell," Fialko said. "It could be tomorrow or it could be 10 years or more from now," he concluded in September of 2005.

The Cascadia Connection

Recent studies of past earthquake traces on both the northern San Andreas Fault and the southern Cascadia subduction zone indicate a correlation in time which may be evidence that quakes on the Cascadia subduction zone may have triggered most of the major quakes on the northern San Andreas during at least the past 3,000 years or so. The Cascadia Subduction zone is a Subduction zone, a type of convergent plate boundary that stretches from northern Vancouver Island to The evidence also shows the rupture direction going from north to south in each of these time-correlated events. The 1906 San Francisco Earthquake seems to have been a major exception to this correlation, however, as it was not preceded by a major Cascadia quake, and the rupture moved mostly from south to north. ^[4]

Notable earthquakes

The San Andreas Fault has had some notable earthquakes in historic times:

• 1857 Fort Tejon earthquake — 350 kilometers were ruptured in central and southern California. An earthquake is the result of a sudden release of energy in the Earth 's crust that creates Seismic waves Earthquakes are recorded with a Seismometer Though it is known as the Fort Tejon earthquake, the epicenter is thought to have been located far to the north, just south of Parkfield. Only two deaths were reported. The magnitude was about 8. The Richter magnitude scale, or more correctly local magnitude M L scale assigns a single number to quantify the amount of seismic energy released 0
• 1906 San Francisco Earthquake — 430 kilometers were ruptured in Northern California. The epicenter was near San Francisco. About 3000 people died in the earthquake and subsequent fires. This time the magnitude was estimated to be 7. 8.
• 1989 Loma Prieta earthquake — 40 kilometers were ruptured (although the rupture did not reach the surface) near Santa Cruz, California, causing 63 deaths and moderate damage in certain vulnerable locations in the San Francisco Bay Area. The Loma Prieta earthquake, also known as the Quake of '89 and the World Series Quake, was a major Earthquake that struck the San Francisco Bay Magnitude this time was about 7. 1. The earthquake also postponed game 3 of the 1989 World Series at Candlestick Park. The 1989 World Series was played between the Oakland Athletics and the San Francisco Giants. Candlestick Park (also commonly referred to as Candlestick or The Stick) is an outdoor sports and entertainment stadium located in San Francisco California
• 2004 Parkfield earthquake — on 28 September 2004 at quarter past 10 in the morning, a magnitude 6. Parkfield Earthquake is a name given to various large Earthquakes that occurred in the vicinity of the little town of Parkfield California, in the United States Events 48 BC - Pompey the Great is assassinated on orders of King Ptolemy of Egypt after landing in Egypt. "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " 0 earthquake struck California on the San Andreas Fault. This earthquake was originally expected in 1993 based on the latest earthquake prediction theories of the time. Eleven years passed before this prediction finally came to pass. Despite the extra time between events the magnitude of the earthquake was no larger than originally expected.

See also: List of earthquakes

The San Andreas Fault in popular culture

• In the mini-series Magnitude 10.5, San Andreas Fault is the center of the whole question which arises in the mini-series. The following is a list of major Earthquakes. USGS list of significant earthquakes This is a list of significant earthquakes as listed by the
• The television version of the theatrically-released film Earthquake features a prologue about the San Andreas, implying that the fault is responsible for the disaster of the title. Earthquake is a 1974 action adventure / disaster / Thriller film that achieved huge box-office success continuing the Disaster film There is no mention of the San Andreas fault in the theatrical version of the film.
• The plot of the original Superman movie had Lex Luthor purchasing massive amounts of land east of the fault and then detonating a nuclear missile at the fault line, causing all land west of the fault to plunge into the sea and turning Luthor's previously purchased barren land into beachfront property. Superman (also known as Superman The Movie) is a 1978 Superhero film based on the DC Comics character of the Lex Luthor is a fictional character that appears in comic books published by DC Comics. A nuclear weapon is an explosive device that derives its destructive force from Nuclear reactions either fission or a combination of fission and fusion.
• The James Bond movie A View to a Kill saw a plot by villain Max Zorin to set off explosives under the San Andreas and Hayward faults in order to destroy Silicon Valley. James Bond 007 is a Fictional character created in 1953 by writer Ian Fleming, who featured him in twelve Novels and two Short story A View To A Kill (1985 is the fourteenth Spy film of the James Bond series, and the seventh and last to star Roger Moore as the fictional Max Zorin is a fictional character and the main antagonist in the James Bond film A View to a Kill. The Hayward Fault Zone is a Geologic fault zone capable of generating significantly destructive Earthquakes About 60 kilometers long it lies mainly along the For the valley nicknamed "Silicone Valley" see San Fernando Valley.
• The video game Grand Theft Auto: San Andreas, is set in a fictional state named after this fault. Grand Theft Auto San Andreas is a sandbox-style action-adventure computer and Video game developed by Rockstar North Also, what is said to be the fault can be seen running through San Fierro, a fictionalized version of San Francisco.
• There is a popular misconception, played up in Curt Gentry's Last Days of the Late, Great State of California (1968) that, eventually, a portion of California will break away from the continental U. An urban legend or urban myth is a form of modern Folklore consisting of stories thought to be factual by those circulating them S. at the fault. Since the San Andreas Fault is a strike-slip (horizontal motion) fault and not a normal (vertical motion) fault nor a rift, this scenario is not plausible. In Geology, a rift is a place where the Earth 's crust and Lithosphere are being pulled apart and is an example of Extensional tectonics
• The aforementioned misconception has been referenced by Bill Hicks' album, Arizona Bay, the Tool song, Ænema, the Presidents of the United States of America song, "Naked and Famous", the Warren Zevon song, "Desperadoes Under the Eaves", and the Steely Dan song "My Old School. William Melvin Hicks ( December 16, 1961 – February 26, 1994) was an American stand-up comedian. Arizona Bay is an album by comedian Bill Hicks, posthumously released in 1997 through Rykodisc. Tool is an American rock band that was formed in 1990 in Los Angeles, California. " Ænema " is a 1996 song by Progressive rock band Tool, released from their 1996 Album Ænima. Warren William Zevon (January 24 1947 &ndash September 7 2003 was a Grammy Award -winning American rock Singer-songwriter and Musician Steely Dan is a American rock band centered on core members Walter Becker and Donald Fagen. " The 1968 song "California Shakin' Away" by the one-local-hit group Shango warns listeners to "get ready to tie up the boat in Idaho. "
• The misconception also forms part of the plot of The End of the World, a popular Flash animation. A Flash animation or Flash cartoon is an animated Film which is created using Adobe Flash animation software and often distributed in the
• On Duke Nukem 3D games. Duke Nukem 3D is a First-person shooter computer game developed by 3D Realms and published by Apogee Software. Duke explored the San Andreas Fault area on the final stages of Episode 1 LA Meltdown on The Abyss
• The song "San Andreas Fault" by Natalie Merchant off her 1995 album Tigerlily is about the San Andreas fault. Natalie Anne O'Shea Merchant (born October 26, 1963 in Jamestown, New York, U Tigerlily is an album by Singer-songwriter Natalie Merchant, released on June 20, 1995 (see 1995 in music)
• In an Animaniacs song about the 1994 Northridge earthquake, the Warners incorrectly claim that the San Andreas Fault was the cause. Steven Spielberg Presents Animaniacs, usually referred to as Animaniacs, is an American animated series, distributed by Warner Bros ^[5]
• In the Three Investigators book The Mystery of the Green Ghost, it is believed that an earthquake caused by the fault line had destroyed the infamous ghost pearls. The Three Investigators was an American juvenile Detective Book series first published as " Alfred Hitchcock and the Three Investigators

See also

• Hayward Fault Zone
• Calaveras Fault
• Garlock Fault
• Geologic timeline of Western North America

References

• Collier, Michael (Dec 1, 1999). A Land in Motion. UC Press. ISBN 0-520-21897-3.  
• Stoffer, Philip W. (2006). Where's the San Andreas fault? A guidebook to tracing the fault on public lands in the San Francisco Bay region. USGS. General Interest Publication 16.  
• The California Earthquake of April 18, 1906: Report of the State Earthquake Investigation Commission, Andrew C. Lawson, chairman, Carnegie Institution of Washington Publication 87, 2 vols. (1908) - Available online at this USGS webpage.
• Lynch, David K. (2006). Field Guide to the San Andreas Fault: See and Touch the World's Most Famous Fault on any one of Twelve Easy Day Trips. Thule Scientific. Full color, GPS coordinates, ISBN 0-9779935-0-7.  

External links

• The Parkfield Experiment
• San Andreas Fault Observatory at Depth
• Southern California Earthquake Data Center: San Andreas Fault
• USGS: The San Andreas Fault
• Scripps Institution of Oceanography (University of California, San Diego) study indicating that an earthquake of magnitude 7.0 or greater is "overdue."
• Source for the Carrizo Plain images (USGS)
• Latest Earthquakes (USGS)
• The Day California Cracks at BusinessWeek online (09/19/05)

Coordinates: 35°07′N 119°39′W / 35.117, -119.65