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

geological fault Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth ...

structure in

Southern California Southern California (commonly shortened to SoCal) is a geographic and Cultural area, cultural List of regions of California, region that generally comprises the southern portion of the U.S. state of California. Its densely populated coastal reg ...

. The fault is part of the trilateral split of the

San Andreas Fault The San Andreas Fault is a continental Fault (geology)#Strike-slip faults, right-lateral strike-slip transform fault that extends roughly through the U.S. state of California. It forms part of the tectonics, tectonic boundary between the Paci ...

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 Lake Elsinore is a natural freshwater lake in Riverside County, California, United States, located east of the Santa Ana Mountains and fed by the San Jacinto River. Originally named ''Laguna Grande'' by Spanish explorers, it was renamed for t ...

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 Pacific Coast Range ...

region between

El Centro El Centro ( Spanish for "The Center") is a city and county seat of Imperial County, California, United States. El Centro is the most populous city in the Imperial Valley, the east anchor of the Southern California Border Region, and the co ...

and

San Diego San Diego ( , ) is a city on the Pacific coast of Southern California, adjacent to the Mexico–United States border. With a population of over 1.4 million, it is the List of United States cities by population, eighth-most populous city in t ...

, 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. Chino Hills State Park preserves open space and habitat in them. Geography The Chin ...

. 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 Trough is a graben rift valley in Riverside County, southern California. It is created by the Elsinore Fault Zone. It is located between the Santa Ana Mountains to the west, and the Temescal Mountains of the Perris Block and the Tem ...

, the Elsinore Fault Zone creates four

graben In geology, a graben () is a depression (geology), depressed block of the Crust (geology), crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German language, German, meaning 'ditch' or 't ...

rift valley A rift valley is a linear shaped lowland between several highlands or mountain ranges produced 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 ...

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 n ...

: the Temescal Valley,

Elsinore Valley Elsinore Valley is a graben rift valley in western Riverside County, California, a part of the Elsinore Trough. The Elsinore Valley is a graben between the Santa Ana Block to the southwest and the Perris Block on the northeast. It is a complex ...

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 ...

, the

Temecula Valley The Temecula Valley (Spanish language, Spanish: ''Valle de Temecula'') 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 Fau ...

, and Wolf Valley. In the Elsinore Trough, the fault zone is split into pairs of parallel strands with the

Glen Ivy North Fault A glen is a valley, typically one that is long and bounded by gently sloped concave sides, unlike a ravine, which is deep and bounded by steep slopes. The word is Goidelic in origin: ''gleann'' in Irish and Scottish Gaelic, ''glion'' in Manx. ...

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 Cou ...

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 The Yuha Desert is a section of the Sonoran Desert located in the Imperial Valley of California, south of Interstate 8, west of El Centro, and north of the international border. Unique aspects of the Yuha Desert include the Oyster Shell Beds, ...

and

Salton Trough The Salton Trough is an active tectonic pull-apart basin, or graben. It lies within the Imperial, Riverside, and San Diego counties of southeastern California and extends south of the Mexico–United States border into the state of Baja Califo ...

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 The Statewide California Earthquake Center (SCEC) is a collaboration of more than 1,000 scientists across 100 research institutions focused primarily on conducting research on earthquakes in Southern California and elsewhere by gathering data, c ...

{{Clear * 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