The
Garlock Fault is a left-lateral strike-slip
fault lineIn geology, a fault or fault line is a planar fracture in rock in which the rock on one side of the fracture has moved with respect to the rock on the other side. Large faults within the Earth's crust are the result of differential or shear motion and active fault zones are the causal locations of...
running approximately northeast-southwest in southern
CaliforniaCalifornia is the most populous state in the United States, and the third largest by area. California is the second most populous sub-national entity in the Americas, behind only São Paulo, Brazil...
. It runs for much of its length along the southern base of the
Tehachapi MountainsThe Tehachapi Mountains are a short transverse range in southern California in the United States, running SW-NE connecting the Coast Ranges on the west with the southern end of the Sierra Nevada mountains on the east...
. 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. Stretching for 250 kilometers, it is the second-longest fault line in California and is one of the most prominent geological features in the southern part of the state.
The Garlock Fault runs from a junction with the
San Andreas FaultThe San Andreas Fault is a continental transform fault that runs a length of roughly through California in the United States. The fault's motion is right-lateral strike-slip...
in Antelope Valley, eastward to a junction with the
Death Valley Fault ZoneThe Death Valley Fault Zone is a right lateral-moving geologic fault in eastern California. It runs from a connection with the Furnace Creek Fault Zone in the Amargosa Valley southward to a junction with the Garlock Fault. It is considered an integral part of the Walker Lane.-References:*...
.
The Garlock is believed to have developed to accommodate the strain differential between the
extensional tectonicsExtensional tectonics is concerned with the structures formed, and the tectonic processes associated with, the stretching of the crust or lithosphere.-Deformation styles:...
of the
Great BasinThe Great Basin is a large, arid region of the western United States. Its boundaries vary depending on how it is defined, but it is most commonly defined as the contiguous endorheic basin roughly between the Wasatch Mountains and the Sierra Nevada mountains. Culturally, the Great Basin is home to...
crust and the right lateral strike-slip faulting of the
Mojave DesertThe Mojave Desert , , locally referred to as the High Desert, occupies a significant portion of southeastern California and smaller parts of central California, southern Nevada, southwestern Utah and northwestern Arizona, in the United States...
crust.
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.
The
Garlock Fault is a left-lateral strike-slip
fault lineIn geology, a fault or fault line is a planar fracture in rock in which the rock on one side of the fracture has moved with respect to the rock on the other side. Large faults within the Earth's crust are the result of differential or shear motion and active fault zones are the causal locations of...
running approximately northeast-southwest in southern
CaliforniaCalifornia is the most populous state in the United States, and the third largest by area. California is the second most populous sub-national entity in the Americas, behind only São Paulo, Brazil...
. It runs for much of its length along the southern base of the
Tehachapi MountainsThe Tehachapi Mountains are a short transverse range in southern California in the United States, running SW-NE connecting the Coast Ranges on the west with the southern end of the Sierra Nevada mountains on the east...
. 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. Stretching for 250 kilometers, it is the second-longest fault line in California and is one of the most prominent geological features in the southern part of the state.
The Garlock Fault runs from a junction with the
San Andreas FaultThe San Andreas Fault is a continental transform fault that runs a length of roughly through California in the United States. The fault's motion is right-lateral strike-slip...
in Antelope Valley, eastward to a junction with the
Death Valley Fault ZoneThe Death Valley Fault Zone is a right lateral-moving geologic fault in eastern California. It runs from a connection with the Furnace Creek Fault Zone in the Amargosa Valley southward to a junction with the Garlock Fault. It is considered an integral part of the Walker Lane.-References:*...
.
The Garlock is believed to have developed to accommodate the strain differential between the
extensional tectonicsExtensional tectonics is concerned with the structures formed, and the tectonic processes associated with, the stretching of the crust or lithosphere.-Deformation styles:...
of the
Great BasinThe Great Basin is a large, arid region of the western United States. Its boundaries vary depending on how it is defined, but it is most commonly defined as the contiguous endorheic basin roughly between the Wasatch Mountains and the Sierra Nevada mountains. Culturally, the Great Basin is home to...
crust and the right lateral strike-slip faulting of the
Mojave DesertThe Mojave Desert , , locally referred to as the High Desert, occupies a significant portion of southeastern California and smaller parts of central California, southern Nevada, southwestern Utah and northwestern Arizona, in the United States...
crust.
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. In the case of the Garlock Fault, this means that the terrain north of the fault is moving westward relative to the terrain south of the fault, which is moving relatively eastward.
Activity
The Garlock moves at a rate of between 2 and 11 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 creepIn geology, aseismic creep is measurable surface displacement along a fault in the absence of notable earthquakes.An example is along the Calaveras fault in Hollister, California. Streets crossing the fault in Hollister show significant offset and several houses sitting atop the fault are notably...
.
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
seismic eventsSeismology is the scientific study of earthquakes and the propagation of elastic waves through the Earth...
when triggered by other
earthquakeAn 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, also known as a seismograph...
s and in one instance by the removal of
ground waterGroundwater is water located beneath the ground surface in soil pore spaces and in the fractures of lithologic formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in...
. These events, as well as continuing
microearthquakeA microearthquake is a very low intensity earthquake which is usually three or less on the Richter scale. Microearthquakes are at times caused by large masses stomping their feet, the first such recorded instance being the Earthquake Game in 1988...
activity and the state of the
scarpsA fault scarp is the topographic expression of faulting attributed to the displacement of the land surface by movement along the fault. It can be caused by differential erosion along an old inactive geologic fault with hard & weak rock, or by a movement on an active fault. In many cases, bluffs...
from previous ruptures, do indicate that the Garlock will produce another major quake at some point in the future.
The most recent notable event was a magnitude 5.7 near the town of
MojaveMojave is a census-designated place in Kern County, California, United States. Mojave is located east of Bakersfield, at an elevation of 2762 feet . The population was 3,836 at the 2000 census. The town is located at the southwestern corner of the Mojave Desert, below the Oak Creek Pass...
on July 11, 1992. It is thought to have been triggered by the
Landers EarthquakeThe 1992 Landers Earthquake was a magnitude 7.3 earthquake that occurred on June 28, 1992 with an epicenter near the town of Landers, California...
, just two weeks earlier.
The last significant ruptures on the Garlock were thought to be in the years 1050 A.D. and 1500 A.D.. Research has pinned the interval between significant ruptures on the Garlock as being anywhere between 200 and 3000 years depending on the segment of the fault.
Geography
The Garlock constitutes one of the borders of the
Mojave DesertThe Mojave Desert , , locally referred to as the High Desert, occupies a significant portion of southeastern California and smaller parts of central California, southern Nevada, southwestern Utah and northwestern Arizona, in the United States...
, and is a significant
geologicGeology is the science and study of the solid and liquid matter that constitutes the Earth. The field of geology encompasses the study of the composition, structure, physical properties, dynamics, and history of Earth materials, and the processes by which they are formed, moved, and changed...
landmark in California. Mountain ranges mark its western edge, and its trace is clearly visible on aerial images of the state.
Relatively few communities lie directly along the Garlock, as it is situated in the desert,
Frazier ParkFrazier Park is an unincorporated community in Kern County, California. Frazier Park is west of Lebec, at an elevation of 4,639 feet . It is one of the Mountain Communities of the Tejon Pass...
,
TehachapiTehachapi is a city incorporated in 1909 located in the Tehachapi Mountains between Bakersfield and Mojave in Kern County, California. Tehachapi is located east-southeast of Bakersfield, at an elevation of...
,
MojaveMojave is a census-designated place in Kern County, California, United States. Mojave is located east of Bakersfield, at an elevation of 2762 feet . The population was 3,836 at the 2000 census. The town is located at the southwestern corner of the Mojave Desert, below the Oak Creek Pass...
, and
JohannesburgJohannesburg is a census-designated place in Kern County, California, in a mining district of the Rand Mountains. Johannesburg is located east-northeast of Randsburg, at an elevation of 3517 feet . The terminus of the Randsburg Railway was here from 1897 to 1933. The population was 176 at the...
being the closest. However, a major rupture along the Garlock would probably be felt in most of the southern part of California.
Nearby Communities
- Frazier Park
- Tehachapi
Tehachapi is a city incorporated in 1909 located in the Tehachapi Mountains between Bakersfield and Mojave in Kern County, California. Tehachapi is located east-southeast of Bakersfield, at an elevation of...
- Mojave
Mojave is a census-designated place in Kern County, California, United States. Mojave is located east of Bakersfield, at an elevation of 2762 feet . The population was 3,836 at the 2000 census. The town is located at the southwestern corner of the Mojave Desert, below the Oak Creek Pass...
- Johannesburg
Johannesburg is a census-designated place in Kern County, California, in a mining district of the Rand Mountains. Johannesburg is located east-northeast of Randsburg, at an elevation of 3517 feet . The terminus of the Randsburg Railway was here from 1897 to 1933. The population was 176 at the...
- Ridgecrest
Ridgecrest was incorporated as a city in 1963. It was formerly known as Crumville. It is located in the Indian Wells Valley in northeastern Kern County, California adjacent to the Naval Air Weapons Station China Lake . Ridgecrest is the only incorporated city along US 395 in Kern County. The...
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