The 1918 San Jacinto earthquake occurred in extreme eastern

San Diego County San Diego County (), officially the County of San Diego, is a county in the southwestern corner of the U.S. state of California. As of the 2020 census, the population was 3,298,634, making it California's second-most populous county and the f ...

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 a ...

on April 21 at . The shock had a moment magnitude of 6.7 and a maximum

Mercalli The Modified Mercalli intensity scale (MM, MMI, or MCS), developed from Giuseppe Mercalli's Mercalli intensity scale of 1902, is a seismic intensity scales, seismic intensity scale used for measuring the intensity of shaking produced by an earthq ...

intensity of IX (''Violent''). Several injuries and one death occurred with total losses estimated to be $200,000.

Tectonic setting

The San Jacinto Fault Zone is a major strike-slip fault zone that runs through

San Bernardino San Bernardino (; Spanish for "Saint Bernardino") is a city and county seat of San Bernardino County, California, United States. Located in the Inland Empire region of Southern California, the city had a population of 222,101 in the 2020 cen ...

, Riverside,

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, and Imperial counties in

. The SJFZ is a component of the larger San Andreas transform system and is considered to be the most seismically active fault zone in the area. Together they relieve the majority of the stress between the

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and

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tectonic plates.

Damage

Many of the buildings in San Jacinto's business district were of poor construction, and all but one frame building and one concrete building collapsed, though high-quality structures did not experience serious damage. Minor damage to other buildings within of San Jacinto also occurred. Roadways and

irrigation Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been devel ...

canals also sustained damage and small sand blows were seen on a farm northwest of San Jacinto. The earthquake occurred on a Sunday afternoon when most of the businesses in San Jacinto were closed and void of customers. The business district had the greatest damage, though Hemet was also severely damaged. Damage to chimneys, windows, and plaster walls occurred to buildings and structures within of San Jacinto. Some of the damage that was inspected included landslides, partially collapsed buildings, and damaged irrigation canals and roads. Ground cracks were observed near the banks of the San Jacinto River.

References

Sources * *

External links

Could a great quake strike on the enigmatic San Jacinto fault?
– Temblor, Inc. * {{Earthquakes in the United States Earthquakes in California 1918 earthquakes 1918 in California 1918 natural disasters in the United States

Tectonic setting

Damage

See also

References

External links