The Elsinore Fault Zone is a large right-lateral strike-slip

geological fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectoni ...

structure in

Southern California Southern California (commonly shortened to SoCal) is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most populous urban ...

. The fault is part of the trilateral split of the

San Andreas fault The San Andreas Fault is a continental transform fault that extends roughly 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) ...

system and is one of the largest, though quietest faults in Southern California.

Fault characteristics

The Elsinore fault zone, not including Whittier, Chino, and Laguna Salada faults, is long with a slip-rate of 4.0 millimeters/year (0.15 in/yr). It is estimated that this zone is capable of producing a quake of 6.5–7.5 M_W. The projected interval between major rupture events is 250 years. The last major rupture event on the main Elsinore fault was in 1910 with a 6 M_W earthquake centered just northwest of the city of Lake Elsinore.

Fault segments and geography

The fault runs from the mountainous

Peninsular Ranges The Peninsular Ranges (also called the Lower California province) are a group of mountain ranges that stretch from Southern California to the southern tip of the Baja California peninsula; they are part of the North American Coast Ranges, which ...

region between El Centro and

San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the eighth most populous city in the United States ...

, northwest to the Chino Hills range and

Chino Hills The Chino Hills are a mountain range on the border of Orange, Los Angeles, and San Bernardino counties, California, with a small portion in Riverside County. The Chino Hills State Park preserves open space and habitat in them. Geography The C ...

. On the southern end of the fault zone is the southeastern extension of the Elsinore fault zone, the

Laguna Salada Fault The Laguna Salada Fault is a geological fault between the United States and Mexico. About long, it straddles the Imperial County-California–Baja California border. Earthquakes 1892 According to some seismologists the 1892 Laguna Salada ...

. At its northern end, the Elsinore fault zone splits into two segments, the Chino Fault and the

Whittier Fault The Whittier Fault is a geologic fault located in eastern Los Angeles County in Southern California, that is one of the two upper branches of the Elsinore Fault Zone, with the Chino Fault the second. Geology The Whittier Fault is a right-la ...

. In the Elsinore Trough, the Elsinore fault zone creates four

graben In geology, a graben () is a depressed block of the crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German, meaning 'ditch' or 'trench'. The word was first used in the geologic conte ...

rift valley A rift valley is a linear shaped lowland between several highlands or mountain ranges created by the action of a geologic rift. Rifts are formed as a result of the pulling apart of the lithosphere due to extensional tectonics. The linear d ...

s between the Santa Ana Mountain Block and the

Perris Block The Perris Block is the central block of three major fault-bounded blocks of the northern part of the Peninsular Ranges. The Perris Block lies between the Santa Ana Block to the west and the San Jacinto Block to the east. The Perris Block, was ...

: the Temescal Valley, the Elsinore Valley with its large

sag pond A sag pond is a body of fresh water collected in the lowest parts of a depression formed between two sides of an active strike-slip, transtensional or normal fault zone. Formation A sag pond is formed along a strike-slip fault, which may creat ...

of Lake Elsinore and the

Temecula Valley The Temecula Valley is a graben rift valley in western Riverside County, California. The Temecula Valley is one of the graben valleys making up the Elsinore Trough, created by the Elsinore Fault Zone. It lies between the Wildomar Fault on th ...

and Wolf Valley. In the Elsinore Trough the fault zone is split into pairs of parallel strands with the Glen Ivy North Fault and Lee Lake Fault forming the first valley, the Glen Ivy South Fault and

Willard Fault Willard may refer to: People * Willard (name) Geography Places in the United States * Willard, Colorado * Willard, Georgia * Willard, Kansas * Willard, Kentucky * Willard, Michigan, a small unincorporated community in Beaver Township, Bay C ...

s the second and the Willard and Wildomar Faults the last two valleys to the southeast. A multi-year study published in 2018 suggests a connection between the Elsinore Fault and other fault lines farther south, in Mexico: "...observations of the Yuha Desert and Salton Trough suggest that the 2010 M7.2 El Mayor ‐ Cucapah earthquake rupture, the Laguna Salada fault in Baja California, Mexico, and the Elsinore fault in California are part of the same fault system."

References

External links

M6.5 Earthquake on the Elsinore Fault (Santa Ana)
– Southern California Earthquake Center {{Coord missing, Riverside County, California * Seismic faults of California Strike-slip faults Geology of Los Angeles County, California Geology of Orange County, California Geology of Riverside County, California Geology of San Bernardino County, California Geology of San Diego County, California Inland Empire Natural history of Los Angeles County, California Natural history of Orange County, California Natural history of Riverside County, California Natural history of San Bernardino County, California Peninsular Ranges

Fault characteristics

Fault segments and geography

References

Further reading

External links