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 (Spanish language, Spanish: ''Valle de Santa Clara'') is a geologic trough in Northern California that extends south–southeast from San Francisco to Hollister, California, Hollister. The longitudinal valley is bordered ...

Northern California Northern California (commonly shortened to NorCal) is a geocultural region that comprises the northern portion of the U.S. state of California, spanning the northernmost 48 of the state's List of counties in California, 58 counties. Northern Ca ...

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

Mercalli intensity The Modified Mercalli intensity scale (MM, MMI, or MCS) measures the effects of an earthquake at a given location. This is in contrast with the seismic magnitude usually reported for an earthquake. Magnitude scales measure the inherent force or ...

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. Determination The primary purpose of a ...

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 a ...

of the

California Coast Ranges The Coast Ranges of California span from Del Norte County, California, Del Norte or Humboldt County, California, south to Santa Barbara County, California, Santa Barbara County. The other three coastal California mountain ranges are the Trans ...

. 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 and recreation ...

) sustained serious damage with financial losses of at least

US$ The United States dollar (Currency symbol, symbol: Dollar sign, $; ISO 4217, currency code: USD) is the official currency of the United States and International use of the U.S. dollar, several other countries. The Coinage Act of 1792 introdu ...

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 aseis ...

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

Sacramento Sacramento ( or ; ; ) is the capital city of the U.S. state of California and the seat of Sacramento County. Located at the confluence of the Sacramento and American Rivers in Northern California's Sacramento Valley, Sacramento's 2020 p ...

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 craft of building a structure with brick, stone, or similar material, including mortar plastering which are often laid in, bound, and pasted together by mortar (masonry), mortar. The term ''masonry'' can also refer to the buildin ...

buildings in the city. The communities of San Jose, San Martin and

Coyote The coyote (''Canis latrans''), also known as the American jackal, prairie wolf, or brush wolf, is a species of canis, canine native to North America. It is smaller than its close relative, the Wolf, gray wolf, and slightly smaller than the c ...

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 form the ...

, 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 The 1979 Coyote Lake earthquake occurred at on August 6 with a Moment magnitude scale, moment magnitude of 5.7 and a maximum Mercalli intensity scale, Mercalli Intensity of VII (''Very strong''). The shock occurred on the Calaveras Fault near ...

'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), founded as the Geological Survey, is an agency of the U.S. Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on Mar ...

* {{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 ...

Morgan Hill, California 1984 earthquakes 1984 in California April 1984 in the United States

Earthquake

Damage

Aftershocks

See also

References

External links