Editing Garlock Fault

{{Short description|Fault running along the margins of the Mojave Desert of Southern California, United States}}
[[Image:Garlock Fault.jpg|thumb|upright=1.35|Perspective view of Garlock Fault]]
The '''Garlock Fault''' is a left-lateral [[strike-slip fault]] running northeast–southwest along the north margins of the [[Mojave Desert]] of [[Southern California]], for much of its length along the southern base of the [[Tehachapi Mountains]].

==Geography==
[[File:USGS Garlock Fault Zone map.png|thumb|upright=1.85|Garlock Fault Zone map]]
{{Unreferenced section|date=August 2020}}
Stretching for  {{convert|250|km|mi|sp=us}}, it is the second-longest fault in California, and one of the most prominent geological features in the southern part of the state.  It marks the northern boundary of the area known as the Mojave Block, as well as the southern ends of the [[Sierra Nevada]] and the valleys of the westernmost [[Basin and Range province]].

The Garlock Fault runs from a junction with the [[San Andreas Fault]] in the [[Antelope Valley, California|Antelope Valley]], eastward to a junction with the [[Death Valley Fault Zone]] in the eastern Mojave Desert. It is named after the historic mining town of [[Garlock, California|Garlock]], founded in 1894 by Eugene Garlock and now a [[ghost town]].  Relatively few communities lie directly along the Garlock, as it is primarily situated in the desert, with [[Frazier Park, California|Frazier Park]], [[Tehachapi, California|Tehachapi]], [[Mojave, California|Mojave]], and [[Johannesburg, California|Johannesburg]] being the closest to it.

==Geology==
The Garlock Fault is believed to have developed to accommodate the strain between the [[extensional tectonics]] of the [[Great Basin]] crust and the right lateral strike-slip faulting of the [[Mojave Desert]] crust.<ref>{{cite book|url=https://books.google.com/books?id=h8fVs7EgaJEC&pg=PA375|title=Classic Cordilleran Concepts|access-date=2008-08-10|publisher=Department of Geology, University of Kansas|isbn=9780813723389|date=January 1999}}</ref>

Unlike most of the other faults in California, slip on the Garlock Fault is left-lateral; that is, the land on the other side of the fault moves to the left from the perspective of someone facing the fault.  Thus, the terrain north of the fault is moving westward and that on the south is moving eastward.

== Activity ==
The Garlock Fault moves at a rate of between 2 and 11&nbsp;mm a year, with an average slip of around 7 millimeters. While most of the fault is locked, certain segments have been shown to move by [[aseismic creep]], which is motion without resulting earthquakes.

The Garlock is not considered to be a particularly [[active fault]], seldom producing any shaking detectable by humans, although it has been known to generate sympathetic [[Seismology|seismic events]] when triggered by other [[earthquake]]s and in one instance by the removal of [[groundwater|ground water]]. These events, as well as continuing [[microearthquake]] activity and the state of the [[fault scarp|scarps]] from previous ruptures, do indicate that the Garlock will produce another major quake at some point in the future.<ref>{{cite journal|url=http://bssa.geoscienceworld.org/cgi/content/abstract/73/6A/1721 |title=Seismicity of the Garlock fault, California |first1=L.|last1=Astiz|first2=C. R.|last2=Allen|author-link2=Clarence Allen (geologist)|journal=Bulletin of the Seismological Society of America|publisher=[[Seismological Society of America]]|year=1983|volume=73|issue=6A|pages=1721–1734|doi=10.1785/BSSA07306A1721 }}</ref>

A study published in October 2019 in the journal ''[[Science (journal)|Science]]'' indicated that a part of the Garlock fault slipped after being triggered by the [[2019 Ridgecrest earthquakes|series of earthquakes in the Ridgecrest area]] which occurred in July 2019.<ref name=Time20181018>{{cite web|url=https://time.com/5705085/garlock-fault-ridgecrest-earthquake-california/|title=Scientists: Movement Detected Along California Fault That Could Cause an 8-Magnitude Earthquake|date=October 18, 2019|website=Time}}</ref> Reports in the [[Los Angeles Times]] indicated that a magnitude 8 earthquake along the Garlock fault would have the potential for grave disaster.<ref name=Time20181018 />

The last significant ruptures on the Garlock were thought to be in the years 1050 AD and 1500 AD. Research has pinned the interval between significant ruptures on the Garlock as being anywhere between 200 and 3,000 years, depending on the segment of the fault.<ref name=bigone>{{cite news|url=http://www.latimes.com/local/lanow/la-me-ln-earthquake-fault-cluster-20150422-story.html|title=The Big One could trigger series of large earthquakes, study finds|work=Los Angeles Times|date= April 22, 2015|first= Rong-Gong |last= Lin II}}</ref> The most recent notable event in the Garlock Fault Zone was a magnitude 5.7 near the town of [[Mojave, California|Mojave]] on July 11, 1992.<ref name="SCEDC Major Faults"/> It is thought to have been triggered by the [[1992 Landers earthquake|Landers earthquake]], just two weeks earlier.<ref name="SCEDC Major Faults">{{cite web |title=Garlock Fault Zone |url=https://scedc.caltech.edu/significant/garlock.html |publisher=Southern California Earthquake Data Center |access-date=17 October 2019}}</ref> However, no surface slippage of the fault itself had been recorded in modern times until 2019. Following [[2019 Ridgecrest earthquakes|a series of earthquakes]] on nearby minor faults in late July 2019, the Garlock Fault was observed moving about 2&nbsp;cm&nbsp;(0.8&nbsp;in)<ref name="KTLA 2019"/> between July and October accompanied by numerous minor earthquakes, a state known as [[aseismic creep|fault creep]], and producing a bulge in land observed by satellite radar images.<ref name="KTLA 2019">{{cite news |title=Unprecedented Movement on Mojave Desert Fault Capable of Magnitude 8.0 Earthquake: Caltech Study |url=https://ktla.com/2019/10/17/unprecedented-movement-detected-on-mojave-desert-fault-capable-of-magnitude-8-0-earthquake-caltech/ |access-date=18 October 2019 |publisher=KTLA |agency=Associated Press |date=October 17, 2019}}</ref><ref name="LAT 2019">{{cite news |title=Unprecedented movement detected on California earthquake fault capable of 8.0 temblor |url=https://www.latimes.com/california/story/2019-10-17/unprecedented-movement-recorded-on-california-earthquake-capable-of-8-0-temblor |url-access=limited |access-date=18 October 2019 |newspaper=Los Angeles Times |date=October 17, 2019}}</ref><ref>{{citation|doi=10.1126/science.aaz0109|pmid=31624209|bibcode=2019Sci...366..346R|title=Hierarchical interlocked orthogonal faulting in the 2019 Ridgecrest earthquake sequence|journal=Science|volume=366|issue=6463|pages=346–351|year=2019|last1=Ross|first1=Zachary E.|last2=Idini|first2=Benjamín|last3=Jia|first3=Zhe|last4=Stephenson|first4=Oliver L.|last5=Zhong|first5=Minyan|last6=Wang|first6=Xin|last7=Zhan|first7=Zhongwen|last8=Simons|first8=Mark|last9=Fielding|first9=Eric J.|last10=Yun|first10=Sang-Ho|last11=Hauksson|first11=Egill|last12=Moore|first12=Angelyn W.|last13=Liu|first13=Zhen|last14=Jung|first14=Jungkyo|s2cid=204772194|url=https://authors.library.caltech.edu/99382/2/aaz0109_Ross_SM.pdf|doi-access=free}}</ref>

==References==
{{Reflist}}

==External links==
*[https://web.archive.org/web/20051125075057/http://www.data.scec.org/fault_index/garlock.html Southern California Earthquake Data Center: Faults in Southern California]

{{California Faults}}
{{Faults}}

[[Category:Seismic faults of California]]
[[Category:Natural history of the Mojave Desert]]
[[Category:Natural history of Kern County, California]]
[[Category:Natural history of Los Angeles County, California]]
[[Category:Natural history of San Bernardino County, California]]
[[Category:Tehachapi Mountains]]
[[Category:Strike-slip faults]]