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1899 San Jacinto Earthquake
The 1899 San Jacinto earthquake occurred on Christmas morning (December 25) at 04:25 local time in Southern California. The estimated moment magnitude 6.7 earthquake had an epicenter located 10 miles southeast of San Jacinto. The earthquake had a maximum Mercalli intensity of IX (''Violent''). Severe damage occurred, amounting to US$50,000 (1899 rate), as well as six fatalities. Tectonic setting The mainshock occurred on a segment of the San Jacinto Fault Zone. This highly segmented, 210-km-long strike-slip fault that forms part of the boundary between the North American and Pacific plates. The fault is part of a complex plate boundary system known as the San Andreas Fault System. It runs parallel to the San Andreas Fault, west of the Salton Sea, and is separated from the San Andreas Fault by the San Jacinto Mountains to its east. It cuts under cities including Hemet, Colton, and San Bernardino along the way, before joining the San Andreas Fault at Devore. Because the fault is s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
San Jacinto Fault Zone
The San Jacinto Fault Zone (SJFZ) is a major strike-slip fault zone that runs through San Bernardino, Riverside, San Diego, and Imperial Counties in Southern California. 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 Pacific and North American tectonic plates. The SJFZ itself consists of many individual fault segments, some of which have only been individualized as recently as the 1980s, but activity along the line of faults has been documented since the 1890s. One segment of the SJFZ, the Anza seismic gap, has not experienced any major activity since instrumental records have been kept. Each segment was evaluated for its seismic risk and was assigned a probability for the occurrence of a large rupture for the thirty-year period starting in 1995. While several of the large earthquakes along the SJFZ have not resulted in sig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1968 Borrego Mountain Earthquake
The 1968 Borrego Mountain earthquake occurred on April 8, at 18:28 PST, near the unincorporated community of Ocotillo Wells in San Diego County. The moment magnitude () 6.6 strike-slip earthquake struck with a focal depth of . Damage was relatively moderate, and the mainshock was assigned a maximum Modified Mercalli intensity (MMI) of VII (''Very strong''). Shaking was felt in Nevada, and Arizona. It was the largest earthquake to strike California since 1952, and its display of afterslip became the subject of scientific interest. Tectonic setting A simplified tectonic bounday map of the Salton Trough area. Red lines show major faults and arrows indicate fault motion. The San Andreas Fault (SAF) is the main plate boundary that defines the margin between the Pacific and North American Plates in California. It is believed to have formed during the Oligocene. The fault has a length of , of which, it is visible for from the Salton Sea to Point Arena. Divided into four distinc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Escondido, California
Escondido is a city in San Diego County, California, United States. Located in the North County region, it was incorporated in 1888, and is one of the oldest cities in San Diego County. It has a population of 151,038 as of the 2020 census. Etymology "Escondido" is a Spanish word meaning "hidden". One source says the name originally referred to ''agua escondida'' or hidden water; another says it meant "hidden treasure". The city is known as ''Eskondiid'' in Kumeyaay. History The Escondido area was first settled by the Luiseño, who established campsites and villages along the creek running through the area. They named the place Mixéelum Pompáwvo or "Mehel-om-pom-pavo." The Luiseno also had another village north of Mixéelum Pompáwvo called Panakare. The Kumeyaay migrated from areas near the Colorado River, settling both in the San Pasqual Valley and near the San Dieguito River in the southwestern and western portions of what is now Escondido. Most of the villages and campsi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rockslide
A rockslide is a type of landslide caused by rock failure in which part of the bedding plane of failure passes through compacted rock and material collapses ''en masse'' and not in individual blocks. Note that a rockslide is similar to an avalanche because they are both slides of debris that can bury a piece of land. While a landslide occurs when loose dirt or sediment falls down a slope, a rockslide occurs only when solid rocks are transported down slope. The rocks tumble downhill, loosening other rocks on their way and smashing everything in their path. Fast-flowing rock slides or debris slides behave similarly to snow avalanches, and are often referred to as rock avalanches or debris avalanches. Definition The term landslide refers to a variety of mass wasting events (geologic slope failures) that include slumps, slides, falls, and flows. The two major types of slides are rotational slides and translational slides. Rockslides are a type of translational event since the rock ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Landslide
Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated grade (slope), slope failures, mudflows, and debris flows. Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients, from mountain ranges to coastal cliffs or even underwater, in which case they are called submarine landslides. Gravity is the primary driving force for a landslide to occur, but there are other factors affecting slope stability that produce specific conditions that make a slope prone to failure. In many cases, the landslide is triggered by a specific event (such as a heavy rainfall, an earthquake, a slope cut to build a road, and many others), although this is not always identifiable. Causes Landslides occur when the slope (or a portion of it) undergoes some processes that change its condition from stable to unstable. This is essentially due to a decrease in the She ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Murrieta, California
Murrieta is a city in southwestern Riverside County, California, United States. The population of Murrieta was 110,949 as of the 2020 census. Murrieta experienced a 133.7% population increase between 2000 and 2010, making Murrieta one of the fastest-growing cities in the state during that period. Largely residential in character, Murrieta is typically characterized as a bedroom community. Murrieta is bordered by the city of Temecula to the south, the cities of Menifee and Wildomar to the north, and the unincorporated community of French Valley to the east. Murrieta is located in the center of the Los Angeles-San Diego mega-region. Murrieta is named for Juan Murrieta, a Californio ranchero who founded the town. History For most of its history, Murrieta was not heavily populated. On June 9, 1873, Domingo Pujol, Francisco Sanjurjo, and Juan and Ezequiel Murrieta purchased the Rancho Pauba and Rancho Temecula Mexican land grants, comprising in the area. Ezequiel returned to S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soboba Band Of Luiseño Indians
The Soboba Band of Luiseño Indians is a federally recognized tribe of Luiseño people, headquartered in Riverside County, California. On June 18, 1883, the Soboba Reservation was established by the United States government in San Jacinto. There are five other federally recognized tribes of Luiseño people in southern California. History Contact and change The Luiseño Indians first encountered Europeans acting as missionaries, and the Luiseño allowed them to come through their community because they were literate. Writers passed through the San Jacinto valley where the Luiseño were settled and recorded much of their culture. Along with missionaries and soldiers were a part of the 1776 Juan Bautista de Anza expedition overland to and through Las Californias sponsored by the Spanish monarchy. took the Luiseño homeland and claimed it theirs for the San Antonio de Pala Asistencia cattle rancho. According to Father Jose Sanchez: "Proceeding in the same direction, we stopped at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Riverside, California
Riverside is a city in and the county seat of Riverside County, California, United States, in the Inland Empire metropolitan area. It is named for its location beside the Santa Ana River. It is the most populous city in the Inland Empire and in Riverside County, and is about southeast of downtown Los Angeles. It is also part of the Greater Los Angeles area. Riverside is the 61st-most-populous city in the United States and 12th-most-populous city in California. As of the 2020 census, it had a population of 314,998. Along with San Bernardino, Riverside is a principal city in the nation's 13th-largest Metropolitan Statistical Area (MSA); the Riverside-San Bernardino-Ontario MSA (pop. 4,599,839) ranks in population just below San Francisco (4,749,008) and above Detroit (4,392,041). Riverside was founded in the early 1870s. It is the birthplace of the California citrus industry and home of the Mission Inn, the nation's largest Mission Revival Style building. It is also home ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Rupture
In seismology, surface rupture (or ground rupture, or ground displacement) is the visible offset of the ground surface when an earthquake rupture along a fault affects the Earth's surface. Surface rupture is opposed by buried rupture, where there is no displacement at ground level. This is a major risk to any structure that is built across a fault zone that may be active, in addition to any risk from ground shaking. Surface rupture entails vertical or horizontal movement, on either side of a ruptured fault. Surface rupture can affect large areas of land. __TOC__ Lack of surface rupture Not every earthquake results in surface rupture, particularly for smaller and deeper earthquakes. In some cases, however, the lack of surface effects is because the fault that moved does not reach the surface. For example, the 1994 Northridge earthquake had a moment magnitude of 6.7, caused major damage in the Los Angeles area, occurred at below the Earth's surface, but did not cause surface ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fissure
A fissure is a long, narrow crack opening along the surface of Earth. The term is derived from the Latin word , which means 'cleft' or 'crack'. Fissures emerge in Earth's crust, on ice sheets and glaciers, and on volcanoes. Ground fissure A , also called an , is a long, narrow crack or linear opening in the Earth's crust. Ground fissures can form naturally, such as from tectonic faulting and earthquakes, or as a consequence of human activity, such as oil mining and groundwater pumping. Once formed, ground fissures can be extended and eroded by torrential rain. They can be hazardous to people and livestock living on the affected surfaces and damaging to property and infrastructure, such as roads, underground pipes, canals, and dams. In circumstances where there is the extensive withdrawal of groundwater, the earth above the water table can subside causing fissures to form at the surface. This typically occurs at the floor of arid valleys having rock formations and compacte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Press-Enterprise
''The Press-Enterprise'' is a paid daily newspaper published by Digital First Media that serves the Inland Empire in Southern California. Headquartered in downtown Riverside, California, it is the primary newspaper for Riverside County, with heavy penetration into neighboring San Bernardino County. The geographic circulation area of the newspaper spans from the border of Orange County to the west, east to the Coachella Valley, north to the San Bernardino Mountains, and south to the San Diego County line. ''The Press-Enterprise'' is a member of the Southern California News Group. The newspaper traces its roots to ''The Press'', which began publishing in 1878, and ''The Daily Enterprise'', which started publishing in 1885. The two papers were merged into one company in 1931, but the company did not begin publishing a daily morning paper named ''The Press-Enterprise'' until 1983. A. H. Belo acquired the company in 1998. In October 2013, A.H. Belo announced that it had reached an a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Government Printing Office
The United States Government Publishing Office (USGPO or GPO; formerly the United States Government Printing Office) is an agency of the legislative branch of the United States Federal government. The office produces and distributes information products and services for all three branches of the Federal Government, including U.S. passports for the Department of State as well as the official publications of the Supreme Court, the Congress, the Executive Office of the President, executive departments, and independent agencies. An act of Congress changed the office's name to its current form in 2014. History The Government Printing Office was created by congressional joint resolution () on June 23, 1860. It began operations March 4, 1861, with 350 employees and reached a peak employment of 8,500 in 1972. The agency began transformation to computer technology in the 1980s; along with the gradual replacement of paper with electronic document distribution, this has led to a stea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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