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1812 Ventura Earthquake
The 1812 Ventura earthquake (also known as the Santa Barbara earthquake) occurred on the morning of December 21 at 11:00 Pacific Standard Time (PST). The 7.1–7.5 magnitude earthquake, with a Modified Mercalli intensity scale rating of X (''Extreme''), along with its resulting tsunami, caused considerable damage to present-day Santa Barbara and Ventura County, California, which was at the time a territory of the Spanish Empire. One person was killed as a result of the earthquake while another from the aftershock. The earthquake occurred just as the region was recovering from another event on the 8th of December the same year. Both events are thought to have been related. Geological setting ''see also: Thrust tectonics and Transverse Range'' The San Andreas is the "master fault" of California, it is the main plate boundary in the San Andreas Fault System, consisting of other major active faults. This zone of interaction between the Pacific and North American Plates have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alta California
Alta California ('Upper California'), also known as ('New California') among other names, was a province of New Spain, formally established in 1804. Along with the Baja California peninsula, it had previously comprised the province of , but was split off into a separate province in 1804 (named ). Following the Mexican War of Independence, it became a territory of Mexico in April 1822 and was renamed in 1824. The territory included all of the modern U.S. states of California, Nevada, and Utah, and parts of Arizona, Wyoming, Colorado, and New Mexico. In the 1836 Siete Leyes government reorganization, the two Californias were once again combined (as a single ). That change was undone in 1846, but rendered moot by the U.S. military occupation of California in the Mexican-American War. Neither Spain nor Mexico ever colonized the area beyond the southern and central coastal areas of present-day California and small areas of present-day Arizona, so they exerted no effective cont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 faults, right-lateral strike-slip (horizontal). The fault divides into three segments, each with different characteristics and a different degree of earthquake risk. The slip rate along the fault ranges from /yr. It was formed by a transform boundary. The fault was identified in 1895 by Professor Andrew Lawson of University of California, Berkeley, UC Berkeley, who discovered the northern zone. It is often described as having been named after San Andreas Lake, a small body of water that was formed in a valley between the two plates. However, according to some of his reports from 1895 and 1908, Lawson actually named it after the surrounding San Andreas Valley. Following the 1906 San Francisco earthquake, Lawson concluded that the fault extende ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1857 Fort Tejon Earthquake
The 1857 Fort Tejon earthquake occurred at about 8:20 a.m. (Pacific time) on January 9 in central and Southern California. One of the largest recorded earthquakes in the United States, with an estimated moment magnitude of 7.9, it ruptured the southern part of the San Andreas Fault for a length of about 225 miles (350 km), between Parkfield and Wrightwood. Though the shock was centered near Parkfield, the event is referred to as the Fort Tejon earthquake, because that was the location of the greatest damage. Fort Tejon is just north of the junction of the San Andreas and Garlock Faults, where the Tehachapi, San Emigdio, and Sierra Pelona Transverse Ranges come together. The earthquake is the most recent large event to occur along that portion of the San Andreas Fault, and is estimated to have had a maximum perceived intensity of IX (''Violent'') on the Modified Mercalli scale (MMI) near Fort Tejon in the Tehachapi Mountains, and along the San Andreas Fault from Mil Potre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fort Tejon
Fort Tejon in California is a former United States Army outpost which was intermittently active from June 24, 1854, until September 11, 1864. It is located in the Grapevine Canyon (''La Cañada de las Uvas'') between the San Emigdio Mountains and Tehachapi Mountains. It is in the area of Tejon Pass along Interstate 5 in Kern County, California, the main route through the mountain ranges separating the Central Valley from the Los Angeles Basin and Southern California. The fort's location protected the San Joaquin Valley from the south and west. Purpose The fort's mission was to suppress stock rustling and protect settlers from attacks by discontent Californios (pre-statehood residents), and Native American tribes, including the Paiute and Mojave, and to monitor the less aggressive Emigdiano living nearby. The Emigdiano, who were closely related to the Chumash of the coastal and interior lands to the west, had several villages near Fort Tejon. After the earlier Spanish and Mexi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earthquake Rupture
In seismology, an earthquake rupture is the extent of slip that occurs during an earthquake in the Earth's crust. Earthquakes occur for many reasons that include: landslides, movement of magma in a volcano, the formation of a new fault, or, most commonly of all, a slip on an existing fault. Nucleation A tectonic earthquake begins by an initial rupture at a point on the fault surface, a process known as nucleation. The scale of the nucleation zone is uncertain, with some evidence, such as the rupture dimensions of the smallest earthquakes, suggesting that it is smaller than 100 m while other evidence, such as a slow component revealed by low-frequency spectra of some earthquakes, suggest that it is larger. The possibility that the nucleation involves some sort of preparation process is supported by the observation that about 40% of earthquakes are preceded by foreshocks. However, some large earthquakes, such as the M8.6 1950 India - China earthquake., have no foreshocks and it re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dendrochronology
Dendrochronology (or tree-ring dating) is the scientific method of dating tree rings (also called growth rings) to the exact year they were formed. As well as dating them, this can give data for dendroclimatology, the study of climate and atmospheric conditions during different periods in history from wood. Dendrochronology derives from Ancient Greek (), meaning "tree", (), meaning "time", and (), "the study of". Dendrochronology is useful for determining the precise age of samples, especially those that are too recent for radiocarbon dating, which always produces a range rather than an exact date. However, for a precise date of the death of the tree a full sample to the edge is needed, which most trimmed timber will not provide. It also gives data on the timing of events and rates of change in the environment (most prominently climate) and also in wood found in archaeology or works of art and architecture, such as old panel paintings. It is also used as a check in radiocar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
USGS - San Andreas Fault Zone
The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientist A scientist is a person who conducts Scientific method, scientific research to advance knowledge in an Branches of science, area of the natural sciences. In classical antiquity, there was no real ancient analog of a modern scientist. Instead, ...s of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization's work spans the disciplines of biology, geography, geology, and hydrology. The USGS is a fact-finding research organization with no regulatory responsibility. The agency was founded on March 3, 1879. The USGS is a bureau of the United States Department of the Interior; it is that department's sole scientific agency. The USGS employs approximately 8,670 people and is headquartered in Reston, Virginia. The USGS also has major offices ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Garlock Fault
The Garlock Fault is a left-lateral strike-slip fault running northeast–southwest along the north margins of the Mojave Desert of Southern California, for much of its length along the southern base of the Tehachapi Mountains. Geography Stretching for , it is the second-longest fault in California, and one of the most prominent geological features in the southern part of the state. It marks the northern boundary of the area known as the Mojave Block, as well as the southern ends of the Sierra Nevada and the valleys of the westernmost Basin and Range province. The Garlock Fault runs from a junction with the San Andreas Fault in the Antelope Valley, eastward to a junction with the Death Valley Fault Zone in the eastern Mojave Desert. It is named after the historic mining town of Garlock, founded in 1894 by Eugene Garlock and now a ghost town. Relatively few communities lie directly along the Garlock, as it is primarily situated in the desert, with Frazier Park, Tehachapi, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Santa Monica Mountains
The Santa Monica Mountains is a coastal mountain range in Southern California, next to the Pacific Ocean. It is part of the Transverse Ranges. Because of its proximity to densely populated regions, it is one of the most visited natural areas in California. The Santa Monica Mountains National Recreation Area encompasses this mountain range. Geography The range extends approximately east-west from the Hollywood Hills in Los Angeles to Point Mugu in Ventura County. The western mountains, separating the Conejo Valley from Malibu, suddenly end at Mugu Peak as the rugged, nearly impassible shoreline gives way to tidal lagoons and coastal sand dunes of the alluvial Oxnard Plain. The mountain range contributed to the isolation of this vast coastal plain before regular transportation routes reached western Ventura County. The eastern mountains form a barrier between the San Fernando Valley and the Los Angeles Basin, separating "the Valley" on the north and west-central Los Angeles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thrust Fault
A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If the angle of the fault plane is lower (often less than 15 degrees from the horizontal) and the displacement of the overlying block is large (often in the kilometer range) the fault is called an ''overthrust'' or ''overthrust fault''. Erosion can remove part of the overlying block, creating a ''fenster'' (or ''window'') – when the underlying block is exposed only in a relatively small area. When erosion removes most of the overlying block, leaving island-like remnants resting on the lower block, the remnants are called ''klippen'' (singular ''klippe''). Blind thrust faults If the fault plane terminates before it reaches the Earth's surface, it is referred to as a ''blind thrust'' fault. Because of the lack of surface evidence, blind thr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strike-slip Tectonics
Strike-slip tectonics or wrench tectonics is the type of tectonics that is dominated by lateral (horizontal) movements within the Earth's crust (and lithosphere). Where a zone of strike-slip tectonics forms the boundary between two tectonic plates, this is known as a transform or conservative plate boundary. Areas of strike-slip tectonics are characterised by particular deformation styles including: ''stepovers'', ''Riedel shears'', ''flower structures'' and ''strike-slip duplexes''. Where the displacement along a zone of strike-slip deviates from parallelism with the zone itself, the style becomes either transpressional or transtensional depending on the sense of deviation. Strike-slip tectonics is characteristic of several geological environments, including oceanic and continental transform faults, zones of oblique collision and the deforming foreland of zones of continental collision. Deformation styles Stepovers When strike-slip fault zones develop, they typically form as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault (geology)
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep. A ''fault plane'' is the plane that represents the fracture surface of a fault. A ''fault trace'' or ''fault line'' is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geologic maps to represent a fault. A ''fault zone'' is a cluster of parallel faults. However, the term is also used for the zone of crushed rock along a single fault. Prolonged motion along closely spaced faults can blur the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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