The 1984 Morgan Hill earthquake (also known as the Halls Valley earthquake) occurred on April 24 at in the

Santa Clara Valley The Santa Clara Valley is a geologic trough in Northern California that extends 90 miles (145 km) south–southeast from San Francisco to Hollister. The longitudinal valley is bordered on the west by the Santa Cruz Mountains and on the east ...

of Northern California. The shock had a moment magnitude of 6.2 and a maximum

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

of VIII (''Severe''). The

epicenter The epicenter, epicentre () or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates. Surface damage Before the instrumental pe ...

was located near Mount Hamilton in the

Diablo Range The Diablo Range is a mountain range in the California Coast Ranges subdivision of the Pacific Coast Ranges in northern California, United States. It stretches from the eastern San Francisco Bay area at its northern end to the Salinas Valley are ...

of the

California Coast Ranges The Coast Ranges of California span from Del Norte or Humboldt County, California, south to Santa Barbara County. The other three coastal California mountain ranges are the Transverse Ranges, Peninsular Ranges and the Klamath Mountains. P ...

. Nearby communities (including

Morgan Hill Morgan Hill is a city in Santa Clara County, California, at the southern tip of Silicon Valley, in the San Francisco Bay Area. Morgan Hill is an affluent residential community, the seat of several high-tech companies, and a dining, entertainmen ...

) sustained serious damage with financial losses of at least

US$ The United States dollar (symbol: $; code: USD; also abbreviated US$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official ...

7.5 million.

Earthquake

The earthquake occurred along the

Calaveras Fault The Calaveras Fault is a major branch of the San Andreas Fault System that is located in northern California in the San Francisco Bay Area. Activity on the different segments of the fault includes moderate and large earthquakes as well as aseismi ...

, with the epicenter northeast of San Jose, and at a depth of . The shock was felt in

Sacramento ) , image_map = Sacramento County California Incorporated and Unincorporated areas Sacramento Highlighted.svg , mapsize = 250x200px , map_caption = Location within Sacramento ...

in California's central valley.

Damage

The earthquake was reported to be felt over an area of .

was the worst affected, with a number of mobile homes sliding off foundations, and moderate damage to several

masonry Masonry is the building of structures from individual units, which are often laid in and bound together by mortar; the term ''masonry'' can also refer to the units themselves. The common materials of masonry construction are bricks, building ...

buildings in the city. The communities of San Jose, San Martin and Coyote were some areas that experienced minor damage. In

Santa Clara County Santa Clara County, officially the County of Santa Clara, is the sixth-most populous county in the U.S. state of California, with a population of 1,936,259, as of the 2020 census. Santa Clara County and neighboring San Benito County together f ...

, over 550 buildings were reported to have received at least minor damage.

Aftershocks

The outline of aftershocks show that the rupture propagated southeast over a section of the fault, as far as San Martin, to the location of the 1979 Coyote Lake earthquake's mainshock. That event's aftershock zone also stretched to the southeast.

References

External links

M 6.2 – Northern California
–

United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

* {{DEFAULTSORT:Morgan Hill earthquake

1984 Events January * January 1 – The Bornean Sultanate of Brunei gains full independence from the United Kingdom, having become a British protectorate in 1888. * January 7 – Brunei becomes the sixth member of the Association of Southeas ...

1984 earthquakes 1984 in California April 1984 events in the United States

Earthquake

Damage

Aftershocks

See also

References

External links