The 1992 Joshua Tree earthquake occurred at 9:50:25 p.m.
PDT (04:50:25 UTC) on April 22 in
Southern California
Southern California (commonly shortened to SoCal) is a geographic and Cultural area, 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 po ...
. The
magnitude 6.2 earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...
struck under the Little San Bernadino Mountains, near the town of
Joshua Tree, California
Joshua Tree is a census-designated place (CDP) in San Bernardino County, California, San Bernardino County, California, United States. The population was 7,414 at the 2010 census. At approximately above sea level, Joshua Tree and its surrounding c ...
.
[ Though no deaths were reported, the earthquake caused 32 injuries. 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 VII (''Very Strong'') was observed in Joshua Tree and caused light to moderate damage.[ The event preceded the ]Landers
Landers may refer to:
People
* Landers (surname), a list of people surnamed Landers (including fictional people)
Places
* Landers, California, United States
* Landers Peaks, group of peaks in the northern portion of Alexander Island, Antarct ...
and Big Bear
Big Bear, also known as ( cr, ᒥᐢᑕᐦᐃᒪᐢᑿ; – 17 January 1888[Mistahimaskwa](_blank)
...
earthquakes by two months but is now recognized as the beginning of a series of major earthquakes that culminated in two events on June 28, 1992.
Earthquake
The Joshua Tree mainshock struck at 9:50:25 p.m. It was caused by north-northwest-trending, right-lateral strike-slip faulting on the Eureka Peak fault which is at least long and possibly handles a significant portion of the slip transferred from the San Andreas Fault
The San Andreas Fault is a continental transform fault that extends roughly through California. It forms the tectonics, tectonic boundary between the Pacific Plate and the North American Plate, and its motion is Fault (geology)#Strike-slip fau ...
zone. Its epicenter was centered about east of Downtown Los Angeles
Downtown Los Angeles (DTLA) contains the central business district of Los Angeles. In addition, it contains a diverse residential area of some 85,000 people, and covers . A 2013 study found that the district is home to over 500,000 jobs. It is ...
and about deep.[ The shaking was reportedly felt as far away as ]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 List of United States cities by population, eigh ...
, Santa Barbara, California
Santa Barbara ( es, Santa Bárbara, meaning "Saint Barbara") is a coastal city in Santa Barbara County, California, of which it is also the county seat. Situated on a south-facing section of coastline, the longest such section on the West Coas ...
, Las Vegas
Las Vegas (; Spanish for "The Meadows"), often known simply as Vegas, is the 25th-most populous city in the United States, the most populous city in the state of Nevada, and the county seat of Clark County. The city anchors the Las Vegas ...
, Yuma, Arizona
Yuma ( coc, Yuum) is a city in and the county seat of Yuma County, Arizona, United States. The city's population was 93,064 at the 2010 census, up from the 2000 census population of 77,515.
Yuma is the principal city of the Yuma, Arizona, M ...
, and Phoenix, Arizona
Phoenix ( ; nv, Hoozdo; es, Fénix or , yuf-x-wal, Banyà:nyuwá) is the List of capitals in the United States, capital and List of cities and towns in Arizona#List of cities and towns, most populous city of the U.S. state of Arizona, with 1 ...
.[ Approximately two months later, the strongest earthquake in 40 years since the ]1952 Kern County earthquake
The 1952 Kern County earthquake occurred on July 21 in the southern San Joaquin Valley and measured 7.3 on the moment magnitude scale. The main shock occurred at 4:52 am Pacific Daylight Time (11:52 UTC), killed 12 people, injured hundreds mor ...
hit Southern California and caused 92 million dollars in damages.
The magnitude 6.2 earthquake that occurred in Joshua Tree, California, on April 22, 1992, was a previously unmapped north-facing earthquake located about 20 km south of the Mount Pinto fault and about 10 km northeast of the mission and a maximum fault slip of was estimated. It was attributed to the right fault along the Late Quaternary Fault. The Creek is a tributary of the San Andreas Fault system. The proximity of the epicenter to the Coachella Valley segment, a particularly dangerous part of the San Andreas fault, immediately raised concerns that it could be a precursor to a larger earthquake. This prompted the California Department of Emergency Services to issue a warning of possible future activity in the local counties shortly after the earthquake.[
]
Impact
Although this earthquake did not have surface faulting that was observed, the rupture propagated northward 12 miles (19 km) to the town of Joshua Tree, where it caused damage. It caused minor damage to several bridges and minor architectural damage to public school buildings. A supermarket was damaged. 32 people were injured by the quake.[ Of the 170 public school facilities in the earthquake's geographic area, 10 had minor structural damage, ranging from cracks in plaster to hairline cracks in masonry walls. 48 bridges were inspected after the earthquake, and 13 showed signs of movement, nine of which were slightly damaged. None of the bridges suffered damage severe enough to affect its traffic.][
In some areas, it was felt for at least 60 seconds. It temporarily shut down at least one television station, but Downtown Los Angeles electrical service was not affected. The quake rattled Southern California, temporarily disrupting phone service from east of ]Riverside
Riverside may refer to:
Places Australia
* Riverside, Tasmania, a suburb of Launceston, Tasmania
Canada
* Riverside (electoral district), in the Yukon
* Riverside, Calgary, a neighbourhood in Alberta
* Riverside, Manitoba, a former rural m ...
to the Arizona border. At the Hyatt Regency Suites in Palm Springs
Palm Springs (Cahuilla: ''Séc-he'') is a desert resort city in Riverside County, California, United States, within the Colorado Desert's Coachella Valley. The city covers approximately , making it the largest city in Riverside County by land ...
, chief security officer Jerry Iovine reported that guests on the top floor had been temporarily evacuated while construction experts examined the structure of the six-story hotel. The Governor's Office of Emergency Services issued advisories to six counties telling officials in Riverside, San Bernardino, Imperial, Los Angeles, Orange, and San Diego counties that they should be on alert for another, larger quake.
Aftershocks
The earthquake had more than 6,000 aftershocks
In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in the same area of the main shock, caused as the displaced crust adjusts to the effects of the main shock. Large earthquakes can have hundreds to thousand ...
, the largest with a magnitude of 4.8. A foreshock of magnitude 4.6 occurred about two hours before the main quake. The aftershocks spread along a northward trend from about north of the San Andreas Fault northwest of Indio, California
Indio (Spanish language, Spanish for "Indian") is a city in Riverside County, California, Riverside County, California, United States, in the Coachella Valley of Southern California's Colorado Desert region. It lies east of Palm Springs, Califo ...
to the east-striking Mount Pinto Fault and it also preceded the Landers event near the southern end of the future Landers aftershock zones. The aftershock sequence of the Joshua Tree quake also showed a clear relative calm during the period before the Landers rupture.[
]
See also
* List of earthquakes in 1992
This is a list of earthquakes in 1992. Only earthquakes of magnitude 6 or above are included, unless they result in damage or casualties, or are notable for some other reason. All dates are listed according to UTC time.
By death toll
By m ...
* List of earthquakes in California
The earliest known California earthquake was documented in 1769 by the Spanish explorers and Catholic missionaries of the Portolá expedition as they traveled northward from San Diego along the Santa Ana River near the present site of Los Angeles ...
* List of earthquakes in the United States
The following is a list of notable earthquakes and tsunamis which had their epicenter in areas that are now part of the United States with the latter affecting areas of the United States. Those in ''italics'' were not part of the United States whe ...
* 1992 Landers earthquake
The 1992 Landers earthquake occurred on Sunday, June 28 with an epicenter near the town of Landers, California, Landers, California, in San Bernardino County. The shock had a Moment magnitude scale, moment magnitude of 7.3 and a maximum Mercalli ...
* 1992 Big Bear earthquake
References
{{Earthquakes in the United States
Earthquakes in California
1992 earthquakes
1992 in California