San Andreas fault - wikipedia San Andreas fault For other uses, see San Andreas ( disambiguation ). San Andreas Fault Aerial photo of the San Andreas Fault Map of the San Andreas Fault showing relative motion Etymology San Andreas Lake Named by Andrew Lawson Year defined 1895 Country United States State California Cities San Francisco Characteristics Segments Calaveras, Hayward, Elsinore, Imperial, Laguna Salada, San Jacinto Length 1,200 km ( 750 mi ) Displacement 20 -- 35 mm ( 0.79 -- 1.38 in ) / yr Tectonics Plate North American & Pacific Status Active Earthquakes 1857, 1906 ( Mw ~ 7.8 ), 1957 ( Mw 5.7 ), 1989 ( Mw ~ 6.9 ), 2004 Type Transform fault Movement Dextral Age Neogene - Holocene Orogeny Gorda - California - Nevada 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 most significant being the southern segment, which passes within about 35 miles ( 56 km ) of Los Angeles. The slip rate along the fault ranges from 20 to 35 mm ( 0.79 to 1.38 in ) / yr. The fault was first identified in 1895 by Professor Andrew Lawson of UC Berkeley, who discovered the northern zone. It is often described as having been named after San Andreas Lake, a small body of water that was formed in a valley between the two plates. However, according to some of his reports from 1895 and 1908, Lawson actually named it after the surrounding San Andreas Valley. Following the 1906 San Francisco earthquake, Lawson concluded that the fault extended all the way into southern California. In 1953, geologist Thomas Dibblee astounded the scientific establishment with his conclusion that hundreds of miles of lateral movement could occur along the fault. A project called the San Andreas Fault Observatory at Depth ( SAFOD ) near Parkfield, Monterey County, is drilling into the fault to improve prediction and recording of future earthquakes. Contents 1 Fault zones 1.1 Northern 1.2 Central 1.3 Southern 2 Plate boundaries 3 Formation 4 Study 4.1 Early years 4.2 Current research 4.3 The next `` Big One '' 4.4 Cascadia connection 5 Earthquakes 6 See also 7 References 8 Further reading 9 External links Fault zones Aerial photo of the San Andreas Fault in the Carrizo Plain The Vasquez Rocks in Agua Dulce, California are evidence of the San Andreas Fault line and part of the 2,650 - mile Pacific Crest Trail. The Mormon Rocks within Cajon Pass show the physical movement of the San Andreas fault in southern California. 3 - D perspective view of Earth 's San Andreas Fault Northern See also : Calaveras Fault and Hayward Fault Zone The northern segment of the fault runs from Hollister, through the Santa Cruz Mountains, epicenter of the 1989 Loma Prieta earthquake, then up the San Francisco Peninsula, where it was first identified by Professor Lawson in 1895, then offshore at Daly City near Mussel Rock. 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. It returns underwater through the linear trough of Tomales Bay which separates the Point Reyes Peninsula from the mainland, runs just east of the Bodega Heads through Bodega Bay and back underwater, returning onshore at Fort Ross. ( 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. ) From Fort Ross, the northern segment continues overland, forming in part a linear valley through which the Gualala River flows. It goes back offshore at Point Arena. 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. Central The central segment of the San Andreas Fault runs in a northwestern direction from Parkfield to Hollister. 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, where the fault slips continuously without causing earthquakes. Southern See also : Elsinore Fault Zone, Imperial Fault, Laguna Salada Fault, and San Jacinto Fault Zone The southern segment ( also known as the Mojave segment ) begins near Bombay Beach, California. Box Canyon, near the Salton Sea, contains upturned strata associated with that section of the fault. The fault then runs along the southern base of the San Bernardino Mountains, crosses through the Cajon Pass and continues northwest along the northern base of the San Gabriel Mountains. These mountains are a result of movement along the San Andreas Fault and are commonly called the Transverse Range. In Palmdale, a portion of the fault is easily examined at a roadcut for the Antelope Valley Freeway. The fault continues northwest alongside the Elizabeth Lake Road to the town of Elizabeth Lake. As it passes the towns of Gorman, Tejon Pass and Frazier Park, the fault begins to bend northward, forming the `` Big Bend ''. This restraining bend is thought to be where the fault locks up in Southern California, with an earthquake - recurrence interval of roughly 140 -- 160 years. Northwest of Frazier Park, the fault runs through the Carrizo Plain, a long, treeless plain where much of the fault is plainly visible. The Elkhorn Scarp defines the fault trace along much of its length within the plain. The southern segment, which stretches from Parkfield in Monterey County all the way to the Salton Sea, is capable of an 8.1 - magnitude earthquake. At its closest, this fault passes about 35 miles ( 56 km ) to the northeast of Los Angeles. Such a large earthquake on this southern segment would kill thousands of people in Los Angeles, San Bernardino, Riverside, and surrounding areas, and cause hundreds of billions of dollars in damage. Plate boundaries This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. ( December 2015 ) The Pacific Plate, to the west of the fault, is moving in a northwest direction while the North American Plate to the east is moving toward the southwest, but relatively southeast under the influence of plate tectonics. The rate of slippage averages about 33 to 37 millimeters ( 1.3 to 1.5 in ) a year across California. The southwestward motion of the North American Plate towards the Pacific is creating compressional forces along the eastern side of the fault. The effect is expressed as the Coast Ranges. The northwest movement of the Pacific Plate is also creating significant compressional forces which are especially pronounced where the North American Plate has forced the San Andreas to jog westward. This has led to the formation of the Transverse Ranges in Southern California, and to a lesser but still significant extent, the Santa Cruz Mountains ( the location of the Loma Prieta earthquake in 1989 ). 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 reason for this is not clear. Several hypotheses have been offered and research is ongoing. One hypothesis -- which gained interest following the Landers earthquake in 1992 -- suggests the plate boundary may be shifting eastward away from the San Andreas towards 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. Formation Tectonic evolution of the San Andreas Fault. The San Andreas began to form in the mid Cenozoic about 30 Mya ( million years ago ). At this time, a spreading center between the Pacific Plate and the Farallon Plate ( which is now mostly subducted, with remnants including the Juan de Fuca Plate, Rivera Plate, Cocos Plate, and the Nazca Plate ) was beginning to reach the subduction zone off the western coast of North America. As the relative motion between the Pacific and North American Plates was different from the relative motion between the Farallon and North American Plates, the spreading ridge began to be `` subducted '', creating a new relative motion and a new style of deformation along the plate boundaries. These geological features are what are chiefly seen along San Andreas Fault. It also includes a possible driver for the deformation of the Basin and Range, separation of the Baja California Peninsula, and rotation of the Transverse Range. The main southern section of the San Andreas Fault proper has only existed for about 5 million years. The first known incarnation of the southern part of the fault was Clemens Well - Fenner - San Francisquito fault zone around 22 -- 13 Ma. This system added the San Gabriel Fault as a primary focus of movement between 10 -- 5 Ma. Currently, it is believed that the modern San Andreas will eventually transfer its motion toward a fault within the Eastern California Shear Zone. This complicated evolution, especially along the southern segment, is mostly caused by either the `` Big Bend '' and / or a difference in the motion vector between the plates and the trend of the fault and it surrounding branches. Study Early years The fault was first identified in Northern California by UC Berkeley geology professor Andrew Lawson in 1895 and named by him after the Laguna de San Andreas, a small lake which lies in a linear valley formed by the fault just south of San Francisco. Eleven years later, Lawson discovered that the San Andreas Fault stretched southward into southern California after reviewing the effects of the 1906 San Francisco earthquake. Large - scale ( hundreds of miles ) lateral movement along the fault was first proposed in a 1953 paper by geologists Mason Hill and Thomas Dibblee. This idea, which was considered radical at the time, has since been vindicated by modern plate tectonics. Current research Seismologists discovered that the San Andreas Fault near Parkfield in central California consistently produces a magnitude 6.0 earthquake approximately once every 22 years. Following recorded seismic events in 1857, 1881, 1901, 1922, 1934, and 1966, scientists predicted that another earthquake should occur in Parkfield in 1993. It eventually occurred in 2004. Due to the frequency of predictable activity, Parkfield has become one of the most important areas in the world for large earthquake research. In 2004, work began just north of Parkfield on the San Andreas Fault Observatory at Depth ( SAFOD ). The goal of SAFOD is to drill a hole nearly 3 kilometres ( 1.9 mi ) into the Earth 's crust and into the San Andreas Fault. An array of sensors will be installed to record earthquakes that happen near this area. The San Andreas Fault System has been the subject of a flood of studies. In particular, scientific research performed during the last 23 years has given rise to about 3,400 publications. The next `` Big one '' Radar generated 3 - D view of the San Andreas Fault, at Crystal Springs Reservoir near San Mateo, California. A study published in 2006 in the journal Nature found that the San Andreas fault has reached a sufficient stress level for an earthquake of magnitude greater than 7.0 on the moment magnitude scale to occur. This study also found that the risk of a large earthquake may be increasing more rapidly than scientists had previously believed. Moreover, the risk is currently concentrated on the southern section of the fault, i.e. the region around Los Angeles, because massive earthquakes have occurred relatively recently on the central ( 1857 ) and northern ( 1906 ) segments of the fault, while the southern section has not seen any similar rupture for at least 300 years. According to this study, a massive earthquake on that southern section of the San Andreas fault would result in major damage to the Palm Springs - Indio metropolitan area and other cities in San Bernardino, Riverside and Imperial counties in California, and Mexicali Municipality in Baja California. It would be strongly felt ( and potentially cause significant damage ) throughout much of Southern California, including densely populated areas of Los Angeles County, Ventura County, Orange County, San Diego County, Ensenada Municipality and Tijuana Municipality, Baja California, San Luis Rio Colorado in Sonora and Yuma, Arizona. Older buildings would be especially prone to damage or collapse, as would buildings built on unconsolidated gravel or in coastal areas where water tables are high ( and thus subject to soil liquefaction ). The paper concluded : 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 can not tell (... ) It could be tomorrow or it could be 10 years or more from now. Nevertheless, in the ten years since that publication there has not been a substantial quake in the Los Angeles area, and two major reports issued by the U.S. Geological Survey ( USGS ) have made variable predictions as to the risk of future seismic events. The ability to predict major earthquakes with sufficient precision to warrant increased precautions has remained elusive. The U.S. Geological Survey most recent forecast, known as UCERF3 ( Uniform California Earthquake Rupture Forecast 3 ), released in November 2013, estimated that an earthquake of magnitude 6.7 M or greater ( i.e. equal to or greater than the 1994 Northridge earthquake ) occurs about once every 6.7 years statewide. The same report also estimated there is a 7 % probability that an earthquake of magnitude 8.0 or greater will occur in the next 30 years somewhere along the San Andreas Fault. A different USGS study in 2008 tried to assess the physical, social and economic consequences of a major earthquake in southern California. That study predicted that a magnitude 7.8 earthquake along the southern San Andreas Fault could cause about 1,800 deaths and $213 billion in damage. Cascadia connection A 2008 paper, studying past earthquakes along the Pacific coastal zone, found a correlation in time between seismic events on the northern San Andreas Fault and the southern part of the Cascadia subduction zone ( which stretches from Vancouver Island to northern California ). Scientists believe quakes on the Cascadia subduction zone may have triggered most of the major quakes on the northern San Andreas within the past 3,000 years. The evidence also shows the rupture direction going from north to south in each of these time - correlated events. However the 1906 San Francisco earthquake seems to have been the exception to this correlation because the plate movement was moved mostly from south to north and it was not preceded by a major quake in the Cascadia zone. Earthquakes See also : List of earthquakes in California The San Andreas Fault has had some notable earthquakes in historic times : 1857 Fort Tejon earthquake : About 350 kilometers ( 220 mi ) were ruptured in central and southern California. 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. Two deaths were reported. The magnitude was about 7.9. 1906 San Francisco earthquake : About 430 kilometers ( 270 mi ) were ruptured in Northern California. The epicenter was near San Francisco. At least 3,000 people died in the earthquake and subsequent fires. The magnitude was estimated to be 7.8. 1957 San Francisco earthquake : A magnitude 5.7 quake with an epicenter on the San Andreas fault in the ocean west of San Francisco and Daly City. 1989 Loma Prieta earthquake : About 40 kilometers ( 25 mi ) 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. Moment magnitude was about 6.9. This quake occurred on October 17, 1989, at approximately 5 : 04 PM PDT. 2004 Parkfield earthquake : On September 28, 2004 at 10 : 15 a.m. PDT, a magnitude 6.0 earthquake struck the Parkfield area. It was felt across the state, including the San Francisco Bay Area. See also San Francisco Bay Area portal Earthquakes portal California earthquake forecast Central Valley ( California ) Coast Range Geomorphic Province Garlock Fault Geologic timeline of Western North America North Anatolian Fault Ramapo Fault San Andreas ( film ) References ^ Jump up to : `` San Andreas Fault Zone ''. CalTech. Retrieved 2017 - 06 - 20. Jump up ^ `` Earthquake Facts ''. earthquake.usgs.gov. Retrieved 2016 - 05 - 28. Jump up ^ Americansouthwest.net `` Box Canyon '' Jump up ^ Rong - Gong Lin II ( October 8, 2010 ). `` San Andreas fault capable of magnitude 8.1 earthquake over 340 - mile swath of California, researchers say ''. Los Angeles Times. Retrieved 2012 - 02 - 17. Jump up ^ Wallace, Robert E. `` Present - Day Crustal Movements and the Mechanics of Cyclic Deformation ''. The San Andreas Fault System, California. Retrieved 2007 - 10 - 26. Jump up ^ Atwater, T., 1970, Implications of Plate Tectonics for the Cenozoic Tectonic Evolution of Western North America Jump up ^ Powell, R.E. ; Weldon, R.J. ( 1992 ). `` Evolution of the San Andreas fault ''. Annual Reviews of Earth and Planetary Science. 20 : 431 -- 468. Jump up ^ Mason L. Hill ; Thomas Dibblee ( April 1953 ). `` San Andreas, Garlock, and Big faults, California ''. Geological Society of America Bulletin : 443 -- 458. Jump up ^ `` San Andreas Fault Observatory at Depth ''. USGS Earthquake Hazards Program. USGS. Jump up ^ Gizzi F.T. ( 2015 ). `` Worldwide trends in research on the San Andreas Fault System '' ( PDF ). Arabian Journal of Geosciences. 8 ( 12 ) : 10893 -- 10909. doi : 10.1007 / s12517 - 015 - 1878 - 4. Jump up ^ NASA ( June 23, 2009 ). `` NASA Radar Provides 3 - D View of San Andreas Fault ''. National Aeronautics and Space Administration. Retrieved 2012 - 02 - 17. ^ Jump up to : Fialko, Yuri ( 2006 ). `` Interseismic strain accumulation and the earthquake potential on the southern San Andreas fault System '' ( PDF ). Nature. 441 ( 7096 ) : 968 -- 971. Bibcode : 2006Natur. 441... 968F. PMID 16791192. doi : 10.1038 / nature04797. Jump up ^ Geller, Robert J. ( Dec 1997 ). `` Earthquake prediction : a critical review ''. Geophysical Journal International. 131 ( 3 ) : 425 -- 450. Bibcode : 1997GeoJI. 131... 425G. doi : 10.1111 / j. 1365 - 246X. 1997. tb06588. x. Jump up ^ `` New Long - Term Earthquake Forecast for California ''. USGS. Jump up ^ `` The ShakeOut Scenario ''. USGS. Jump up ^ BSSA ( April 3, 2008 ). `` Earthquakes Along The Cascadia And San Andreas Faults May Be Linked, Affecting Risk To San Francisco Bay Region ''. Seismological Society of America. Retrieved 2012 - 02 - 17. Further reading Collier, Michael ( December 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. ISBN 0 - 9779935 - 0 - 7. Full color, GPS coordinates,. External links Wikimedia Commons has media related to San Andreas Fault. The Parkfield, California, Earthquake Experiment at the USGS San Andreas Fault Zone Observatory at Depth at the International Continental Scientific Drilling Program The San Andreas Fault by Sandra S. Schulz and Robert E. Wallace Complete Report for San Andreas fault zone, Peninsula section ( Class A ) No. 1c from the USGS New Scripps Study Reveals San Andreas Fault Set for the ' Big One ' at the Scripps Institution of Oceanography San Andreas Fault at Wallace Creek -- Kite Aerial Photography from the USGS `` Scientists Search for a Pulse in Skies Above Earthquake Country '' at JPL The Day California Cracks at Bloomberg Businessweek Google Maps Satellite View on Geology.com San Andreas Fault in Southern California Seismically active fault zones and tectonic blocks of California Statewide Faults San Andreas Fault Faults, zones, and blocks of Southern California Brawley Seismic Zone Chino Fault Elsinore Fault Zone Elysian Park Fault Garlock Fault Hollywood fault Hosgri Fault Imperial Fault Zone Laguna Salada Fault Newport -- Inglewood Fault Peninsular Ranges Puente Hills Fault Raymond Fault Rose Canyon Fault Salton Trough Salinian Block San Cayetano Fault San Felipe Fault Zone San Gabriel Fault San Jacinto Fault Zone Santa Maria River Fault Santa Ynez Fault Shoreline Fault Sierra Madre Fault Zone Ventura Fault White Wolf Fault Whittier Fault Yorba Linda Fault Faults and zones of Northern California Bartlett Springs Fault Calaveras Fault Clayton - Marsh Creek - Greenville Fault Concord Fault Hayward Fault Zone Healdsburg Fault Maacama Fault Mendocino Fracture Zone Mendocino Triple Junction Mount Diablo Thrust Fault Monta Vista Fault Nacimiento Fault Pleasanton Fault Rinconada Fault San Gregorio Fault San Pablo Fault Seal Cove Fault Serra Fault Silver Creek Fault Tesla Fault West Napa Fault Sierra Nevada faults, zones, and blocks Death Valley Fault Zone Furnace Creek Fault Zone Honey Lake Fault Zone Kern Canyon Fault Maria fold and thrust belt Owens Valley Fault Rescue Lineament - Bear Mountains fault zone Sierra Nevada Batholith Sierra Nevada Fault Sierra Nevada - Great Valley Block Smartville Block Walker Lane California Geological Survey Seismic Hazards Mapping Act Mexico ( list ) State of California Sacramento ( capital ) Topics Culture Food Music `` Myth '' Sports Demographics Earthquakes Economy Education Environment Geography Climate Ecology Flora Fauna Government Districts Congressional delegations Healthcare History Law Landmarks State Historic Landmarks National Historic Landmarks National Natural Landmarks NRHP listings Politics Elections People Protected areas State parks State symbols Transportation Water Index of articles Regions Antelope Valley Big Sur California Coast Ranges Cascade Range Central California Central Coast Central Valley Channel Islands Coachella Valley Coastal California Conejo Valley Cucamonga Valley Death Valley East Bay ( SF Bay Area ) East County ( SD ) Eastern California Emerald Triangle Gold Country Great Basin Greater San Bernardino Inland Empire Klamath Basin Lake Tahoe Greater Los Angeles Los Angeles Basin Lost Coast Mojave Desert Mountain Empire North Bay ( SF ) North Coast North Coast ( SD ) Northern California Owens Valley Oxnard Plain Peninsular Ranges Pomona Valley Sacramento Valley Salinas Valley San Fernando Valley San Francisco Bay Area San Francisco Peninsula San Gabriel Valley San Joaquin Valley Santa Clara Valley Santa Clara River Valley Santa Clarita Valley Santa Ynez Valley Shasta Cascade Sierra Nevada Silicon Valley South Bay ( LA ) South Bay ( SD ) South Bay ( SF ) South Coast Southern Border Region Southern California Tech Coast Transverse Ranges Tri-Valley Victor Valley Wine Country Metro regions Metropolitan Fresno Los Angeles metropolitan area Greater Sacramento San Bernardino - Riverside metropolitan area San Francisco metropolitan area San Diego -- Tijuana Counties Alameda Alpine Amador Butte Calaveras Colusa Contra Costa Del Norte El Dorado Fresno Glenn Humboldt Imperial Inyo Kern Kings Lake Lassen Los Angeles Madera Marin Mariposa Mendocino Merced Modoc Mono Monterey Napa Nevada Orange Placer Plumas Riverside Sacramento San Benito San Bernardino San Diego San Francisco San Joaquin San Luis Obispo San Mateo Santa Barbara Santa Clara Santa Cruz Shasta Sierra Siskiyou Solano Sonoma Stanislaus Sutter Tehama Trinity Tulare Tuolumne Ventura Yolo Yuba Most populous cities Los Angeles San Diego San Jose San Francisco Fresno Sacramento Long Beach Oakland Bakersfield Anaheim Significant seismically active faults of North America North America ( crosses national borders ) Alaska - Aleutian megathrust ( US - RU ) Basin and Range Province ( US - MX ) Cascadia subduction zone ( US - CA ) Clarendon - Linden fault system ( US - CA ) Denali Fault ( US - CA ) Northern Cordilleran Volcanic Province ( CA - US ) Puget Sound faults ( US - CA ) Rio Grande rift ( US - MX ) San Andreas Fault ( US - MX ) Southern Great Lakes Seismic Zone ( US - CA ) Tintina Fault ( US - CA ) Canada Charlevoix Seismic Zone Laurentian Slope Seismic Zone Ottawa - Bonnechere Graben Queen Charlotte Fault Saguenay Graben Saint Lawrence rift system Western Quebec Seismic Zone United States Washington and Oregon Brothers Fault Zone Olympic - Wallowa Lineament Puget Sound ( Seattle Fault, Tacoma Fault ) Walker Lane California Calaveras Fault Garlock Fault Hayward Fault Zone Mendocino Fracture Zone Newport -- Inglewood Fault Puente Hills Fault Rose Canyon Fault San Jacinto Fault Zone ( Elsinore Fault Zone ) Great Basin Independence Valley fault system Moab Fault Teton Fault Wasatch Fault Great Plains Central Oklahoma Fault Zone Humboldt Fault Long Point -- Eureka Heights fault system Nemaha Fault Zone Wilzetta Fault Midwest Marianna Fault New Madrid Seismic Zone Sandwich Fault Zone Wabash Valley Seismic Zone Appalachian Mountains and Atlantic Coast Aiken - Augusta Fault Eastern Tennessee Seismic Zone Middleton Place - Summerville Seismic Zone ( Woodstock Fault ) Northern Appalachians Seismic Zone Ramapo Fault Virginia Seismic Zone Caribbean & Mexico Cayman Trough Chixoy - Polochic Fault Enriquillo -- Plantain Garden fault zone ( Cuba ) Gulf of California Rift Zone Lesser Antilles subduction zone Middle America Trench ( Central America ) Motagua Fault ( Central America ) Pedro Miguel Fault Puerto Rico Trench VIAF : 233720329 GND : 4105280 - 8 Retrieved from `` https://en.wikipedia.org/w/index.php?title=San_Andreas_Fault&oldid=801592384 '' Categories : 1906 San Francisco earthquake Geography of Kern County, California Geography of Los Angeles County, California Geography of Marin County, California Geography of Monterey County, California Geography of Palmdale, California Geography of San Bernardino County, California Geography of San Francisco Geography of San Mateo County, California Geography of Santa Clara County, California Geography of Sonoma County, California Geography of the San Francisco Bay Area Geology of Imperial County, California Geology of Los Angeles County, California Geology of Riverside County, California Geology of San Bernardino County, California History of Southern California Landforms of Humboldt County, California National Natural Landmarks in California Salton Trough Seismic faults of California Strike - 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Question: san andreas fault is what type of plate boundary
Answer: transform