86-542: The Rose Canyon Fault is a right-lateral strike-slip fault that runs in a north–south direction off the coast of San Diego County, California , until it comes ashore near downtown San Diego . The fault is linked to the Newport–Inglewood Fault (NIFZ) in the north and either the Agua Blanca Fault or San Miguel–Vallecitos Fault Zone in the south via en echelon stepovers . Conservative estimates of
172-405: A decollement . Extensional decollements can grow to great dimensions and form detachment faults , which are low-angle normal faults with regional tectonic significance. Due to the curvature of the fault plane, the horizontal extensional displacement on a listric fault implies a geometric "gap" between the hanging and footwalls of the fault forms when the slip motion occurs. To accommodate into
258-860: A plate boundary. This class is related to an offset in a spreading center , such as a mid-ocean ridge , or, less common, within continental lithosphere , such as the Dead Sea Transform in the Middle East or the Alpine Fault in New Zealand. Transform faults are also referred to as "conservative" plate boundaries since the lithosphere is neither created nor destroyed. Dip-slip faults can be either normal (" extensional ") or reverse . The terminology of "normal" and "reverse" comes from coal mining in England, where normal faults are
344-786: A transform boundary between the Pacific plate and the North American plate . Faulting is taken up by three main groups of faults: the San Andreas Fault and linked faults, the eastern California shear zone (ECSZ), and the California Continental Borderland (CCB). The San Andreas system and the ECSZ take up around 85% of the deformation, while the CCB accommodates the rest. The CCB is itself split into
430-644: A California earthquake forecast, which models earthquake occurrence in California. This is a partial list of earthquakes in Southern California. For a full list, see List of earthquakes in California . Note: Earthquakes with epicenters in the Los Angeles Metro Area are marked with the (#) symbol. Other earthquakes mentioned indicates shaking was felt in the region. As of the 2020 United States Census , Southern California has
516-591: A M w 6.7 earthquake or greater, such as the San Andreas Fault , which can produce M w 8.0 or greater. The largest known earthquake in California was the 1857 Fort Tejon earthquake that ruptured 200+ miles (320+ kilometers) of the San Andreas Fault from Parkfield to Wrightwood . With a recurrence interval of roughly 150 years, this part of the San Andreas fault is well within its window to produce another large earthquake. Along with
602-582: A fault hosting valuable porphyry copper deposits is northern Chile's Domeyko Fault with deposits at Chuquicamata , Collahuasi , El Abra , El Salvador , La Escondida and Potrerillos . Further south in Chile Los Bronces and El Teniente porphyry copper deposit lie each at the intersection of two fault systems. Faults may not always act as conduits to surface. It has been proposed that deep-seated "misoriented" faults may instead be zones where magmas forming porphyry copper stagnate achieving
688-410: A fault often forms a discontinuity that may have a large influence on the mechanical behavior (strength, deformation, etc.) of soil and rock masses in, for example, tunnel , foundation , or slope construction. The level of a fault's activity can be critical for (1) locating buildings, tanks, and pipelines and (2) assessing the seismic shaking and tsunami hazard to infrastructure and people in
774-408: A fault's age by studying soil features seen in shallow excavations and geomorphology seen in aerial photographs. Subsurface clues include shears and their relationships to carbonate nodules , eroded clay, and iron oxide mineralization, in the case of older soil, and lack of such signs in the case of younger soil. Radiocarbon dating of organic material buried next to or over a fault shear
860-595: A higher population, with 23.76 million residents as of the 2020 census . The sparsely populated desert region of California occupies a significant portion (part of which has even been proposed to be split into a new county due to cultural, economic and geographic differences relative to the rest of the more urban region) of the area: the Colorado Desert , along with the Colorado River , is located on Southern California's eastern border with Arizona , and
946-611: A population of 23,762,904. Despite a reputation for high growth rates, Southern California's population has grown slower than the state average since the 2000s. This is due to California's growth becoming concentrated in the northern part of the state as result of a stronger, tech-oriented economy in the Bay Area and an emerging Greater Sacramento region. Southern California consists of one Combined Statistical Area , eight Metropolitan Statistical Areas , one international metropolitan area , and multiple metropolitan divisions. The region
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#17328007119641032-473: A population of approximately 4 million, Los Angeles is the most populous city in California and the second most populous in the United States. South of Los Angeles and with a population of approximately 1.4 million is San Diego, the second most populous city in the state and the eighth most populous in the nation. The counties of Los Angeles , San Diego , Orange , Riverside , and San Bernardino are
1118-504: A potential link. The Rose Canyon Fault has little associated historic seismicity, however a magnitude 6–6.5 earthquake in 1862 is often attributed to it. The shock was assigned a Modified Mercalli intensity shaking of VII ( Very strong ). Shaking was widespread and felt in Los Angeles (over 100 mi (160 km) away). However, due to the lack of reports in the area, it is not possible to guarantee that this earthquake occurred on
1204-769: A whole enacted the Alquist Priolo Special Studies Zone Act in the wake of the 1971 San Fernando earthquake . The act prohibits new construction of residential buildings closer than 50 feet (15 m) from a surface rupturing active fault zone. In addition, the act improved safety by requiring new structures (both residential and commercial) to be seismically retrofitted. It also required existing infrastructure to comply. Since 1972, numerous large magnitude earthquakes have struck Southern California with little widespread damage in part due to act. However, exceptions can be noted for epicenters that lie directly on top of densely populated regions such as
1290-494: 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 distinction, as the rock between the faults is converted to fault-bound lenses of rock and then progressively crushed. Due to friction and
1376-502: Is also home to a large surf and skateboard culture. Companies such as Vans , Volcom , Quiksilver , No Fear , Stüssy , RVCA , and Body Glove are all headquartered there. Skateboarder Tony Hawk ; surfers Rob Machado , Timmy Curran , Bobby Martinez , Pat O'Connell , Dane Reynolds , and Chris Ward live in Southern California. Some of the most famous surf locations are in Southern California as well, including Trestles , Rincon , The Wedge , Huntington Beach , and Malibu . Some of
1462-513: Is also known for its mountain resort communities, such as Big Bear Lake , Lake Arrowhead , and Wrightwood , and their ski resorts, like Bear Mountain , Snow Summit , Snow Valley Mountain Resort , and Mountain High . The inland desert city of Palm Springs is also popular. Southern California is generally considered the area of California south of the latitude 35°45', approximately one-third of
1548-687: Is an important government, arts and entertainment, and retail district. Downtown San Diego is the CBD of San Diego, though the city is filled with business districts. These include Carmel Valley , Del Mar Heights , Mission Valley , Rancho Bernardo , Sorrento Mesa , and University City . Most of these districts are located in Northern San Diego and some within North County regions. Los Angeles Orange County Riverside & San Bernardino San Diego Southern California
1634-410: Is home to Los Angeles International Airport , the second-busiest airport in the United States by passenger volume (see World's busiest airports by passenger traffic ) and the third-busiest by international passenger volume (see Busiest airports in the United States by international passenger traffic ); San Diego International Airport , the busiest single-runway airport in the world; Van Nuys Airport ,
1720-568: Is home to two extended metropolitan areas that exceed five million in population. These are the Greater Los Angeles Area at 17,786,419, and San Diego–Tijuana at 5,105,768. Of these metropolitan areas, the Los Angeles-Long Beach-Santa Ana metropolitan area , Riverside-San Bernardino-Ontario metropolitan area , and Oxnard-Thousand Oaks-Ventura metropolitan area form Greater Los Angeles; while
1806-401: Is low to moderate depending on the area. Rain is infrequent, but is often heavy when it does occur, making flash floods an aspect of living in Southern California. This climatic pattern was alluded to in the hit song " It Never Rains (In Southern California) ". While snow is very rare in lower elevations, mountains above 5,000 feet (1,500 m) receive plentiful snowfall in the winter. Since
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#17328007119641892-543: Is often critical in distinguishing active from inactive faults. From such relationships, paleoseismologists can estimate the sizes of past earthquakes over the past several hundred years, and develop rough projections of future fault activity. Many ore deposits lie on or are associated with faults. This is because the fractured rock associated with fault zones allow for magma ascent or the circulation of mineral-bearing fluids. Intersections of near-vertical faults are often locations of significant ore deposits. An example of
1978-434: Is released in part as seismic waves , forming an earthquake . Strain occurs accumulatively or instantaneously, depending on the liquid state of the rock; the ductile lower crust and mantle accumulate deformation gradually via shearing , whereas the brittle upper crust reacts by fracture – instantaneous stress release – resulting in motion along the fault. A fault in ductile rocks can also release instantaneously when
2064-463: The Chesapeake Bay impact crater . Ring faults are the result of a series of overlapping normal faults, forming a circular outline. Fractures created by ring faults may be filled by ring dikes . Synthetic and antithetic are terms used to describe minor faults associated with a major fault. Synthetic faults dip in the same direction as the major fault while the antithetic faults dip in
2150-605: The El Centro metropolitan area and San Diego-Carlsbad-San Marcos metropolitan area form the Southern Border Region . North of Greater Los Angeles are the Santa Barbara , San Luis Obispo , and Bakersfield metropolitan areas. Los Angeles (with a population of approximately 3.9 million people) and San Diego (at nearly 1.4 million people) are the two largest cities in all of California, and are among
2236-712: The Los Angeles metropolitan area ( Los Angeles and Orange counties, with 13.3 million people), the Inland Empire ( Riverside and San Bernardino counties, including the Coachella Valley cities, with 4.3 million people), and the Oxnard–Thousand Oaks–Ventura metropolitan area (0.8 million people). In addition, Southern California contains the San Diego metropolitan area with 3.3 million people, Bakersfield metro area with 0.9 million, and
2322-717: The Mojave Desert shares a border with Nevada to the northeast. Southern California's southern border with Baja California is part of the Mexico–United States border . Southern California encompasses eight metropolitan areas (MSAs), three of which together form the Greater Los Angeles Combined Statistical Area (CSA) with over 18 million people, the second-biggest CSA after the New York CSA . These three MSAs are
2408-760: The Newport–Inglewood-Rose Canyon Fault (located adjacent to SoFi Stadium and responsible for Signal Hill ), the Elsinore Fault (created Lake Elsinore ), the Garlock Fault (which marks boundary between of the Sierra Nevada and the Mojave Desert ), and the Hollywood fault (which is within feet of Capitol Records and is roughly parallel to Hollywood Boulevard ). The United States Geological Survey (USGS) has released
2494-779: The San Diego metropolitan area as they do with the Inland Empire . To the east, the United States Census Bureau considers the San Bernardino and Riverside County areas, Riverside-San Bernardino area as a separate metropolitan area from Los Angeles County. Newly developed exurbs formed in the Antelope Valley , north of Los Angeles, the Victor Valley , and the Coachella Valley with the Imperial Valley . Also, population growth
2580-492: The San Fernando Valley . The area of Santa Monica and Venice (and perhaps some of Culver City) is informally referred to as "Silicon Beach" because of the concentration of financial and marketing technology-centric firms located in the region. The San Bernardino-Riverside Area maintains the business districts of Downtown San Bernardino , Hospitality Business/Financial Centre , University District which are in
2666-480: The Santa Barbara , San Luis Obispo , and El Centro (Imperial County) metropolitan areas. The Southern California Megaregion (or megalopolis ) is larger still, extending northeast into Las Vegas , Nevada and south across the Mexican border into Tijuana . Within Southern California are two major cities, Los Angeles and San Diego , as well as three of the country's largest metropolitan areas . With
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2752-526: The Transverse and Peninsular Ranges with their peaks, and into the large and small interior valleys, to the vast deserts of California . Note: Plate boundary faults are indicated with a (#) symbol. Each year, Southern California has about 10,000 earthquakes. Nearly all of them are too small to be felt. Only several hundred have been greater than magnitude (M w ) 3.0, and only about 15–20 have been greater than M w 4.0. California as
2838-461: The United States ) as well as the Inland Empire (another large metropolitan area). The region generally contains ten of California's 58 counties: Los Angeles , San Diego , Orange , Riverside , San Bernardino , Kern , Ventura , Santa Barbara , San Luis Obispo , and Imperial counties. Although geographically smaller than Northern California in land area, Southern California has
2924-403: The entertainment industry . Other industries include software, automotive, aerospace, finance, biomedical, ports and regional logistics. The region was a leader in the housing bubble from 2001 to 2007, and has been heavily impacted by the housing crash. Since the 1920s, motion pictures, petroleum, and aircraft manufacturing have been major industries. In one of the richest agricultural regions in
3010-711: The Inner (ICB) and Outer Continental Borderlands. The ICB takes up ~6–8 mm (0.24–0.31 in) of the plate boundary's slip, with the Rose Canyon Fault being one of the most hazardous faults in the ICB system. The right-lateral strike-slip fault extends for 30–50 km (19–31 mi) and slips at a rate of 1.1–2 mm (0.043–0.079 in)/yr. The fault begins in San Diego Bay , then runs through La Jolla before turning offshore. It extends north paralleling
3096-546: The Los Angeles Area are the major business districts of Downtown Pasadena , Downtown Burbank , Downtown Santa Monica , Downtown Glendale and Downtown Long Beach . Los Angeles proper has many business districts, such as Downtown LA and those lining Wilshire Boulevard , including Mid-Wilshire , the Miracle Mile , Downtown Beverly Hills , and Westwood ; others include Century City and Warner Center in
3182-399: The M w 6.7 1994 Northridge Earthquake and, to a lesser extent, the smaller M w 5.5 2008 Chino Hills earthquake . The Northridge earthquake occurred on a blind-thrust fault directly underneath the San Fernando Valley , which until the earthquake was previously undiscovered. Seismic retrofitting of existing and new construction is aimed to prevent damage and save lives in
3268-728: The Newport Inglewood–Rose Canyon–Descanso–Agua Blanca Fault Zone. Others favor an interpretation which links the Rose Canyon to the San Miguel-Vallecitos Fault Zone, though just like with the Descanso and Agua Blanca faults, there are no visible faults connecting the two. Other researchers attempting to determine which of the two faults the Rose Canyon connects to in the south provide evidence for both faults having
3354-631: The Rose Canyon Fault via San Diego Bay step overs, however no clear connection has been determined. Around San Diego Bay, the fault splays out into many different strands, such as the Silver Strand and Spanish Bight faults. Some of these splay faults come very close to the Descanso Fault, which in turn links with the Agua Blanca Fault. This leads certain researchers to consider these faults interconnected as one major fault zone,
3440-558: The Rose Canyon Fault with the Newport-Inglewood, and the combined fault zone can produce M7.3–7.4 earthquakes. Sources Fault (geology)#Strike-slip faults 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
3526-587: The Rose Canyon Fault. Trenching of the fault reveals multiple ruptures within the past 8,100 years, including a rupture that occurred between 300 years to shortly before the San Diego Mission was established. Some of these historic ruptures have an estimated magnitude of 7–7.3. The Rose Canyon Fault Zone can produce large earthquakes which can be very destructive due to its proximity to major population centers in Southern California . On
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3612-456: The Southern California desert system. Because of the barrier formed by the Tehachapi and Sierra Nevada ranges, cartographer George Wheeler observed in 1876 that Northern California was better connected to Oregon and Nevada than it was to Southern California. Following the acquisition of the territory of California by the United States, several pro-slavery politicians attempted to arrange
3698-493: The U.S., cattle and citrus were major industries until farmlands were turned into suburbs. Although military spending cutbacks have had an impact, aerospace continues to be a major factor. Southern California is home to many major business districts. Central business districts (CBD) include Downtown Los Angeles , Downtown Riverside , Downtown San Bernardino , downtown San Diego , and the South Coast Metro . Within
3784-432: The aftermath of a major quake, but it cannot guarantee that buildings will be unscathed if the epicenter is relatively close by. The 1994 Northridge earthquake was particularly destructive, causing a substantial number of deaths, injuries, and structural collapses. The quake caused the most property damage of any earthquake in U.S. history at an estimated $ 20 billion. Many Southern California faults are able to produce
3870-555: The centers of their respective metropolitan areas, composed of numerous smaller cities and communities. The urban area is also host to an international San Diego–Tijuana metropolitan region, created by the urban area spilling over into Baja California . The main barrier to urbanization along the Interstate 5 corridor is Camp Pendleton . The cities and communities along Interstate 15 and Interstate 215 are so interrelated that Temecula and Murrieta have as much connection with
3956-612: The cities of San Bernardino and Riverside. In Orange County, has highly developed suburban business centers (also known as edge cities ) including the Anaheim–Santa Ana edge city along I-5; and another, the South Coast Plaza–John Wayne Airport edge city that stretches from the South Coast Metro to the Irvine Business Complex ; Newport Center ; and Irvine Spectrum . Downtown Santa Ana
4042-596: The coastline before connecting with the Newport–Inglewood Fault via short en echelon step overs , and the two faults together extend for 170 km (110 mi). The southern terminus of the Rose Canyon Fault Zone has not been conclusively determined, and is considered to connect to the Descanso and Agua Blanca Faults and/or the San Miguel–Vallecitos Fault Zone. Researchers have suggested that both of these faults may transfer slip to
4128-414: The crust. A thrust fault has the same sense of motion as a reverse fault, but with the dip of the fault plane at less than 45°. Thrust faults typically form ramps, flats and fault-bend (hanging wall and footwall) folds. A section of a hanging wall or foot wall where a thrust fault formed along a relatively weak bedding plane is known as a flat and a section where the thrust fault cut upward through
4214-433: The direction of extension or shortening changes during the deformation but the earlier formed faults remain active. The hade angle is defined as the complement of the dip angle; it is the angle between the fault plane and a vertical plane that strikes parallel to the fault. Ring faults , also known as caldera faults , are faults that occur within collapsed volcanic calderas and the sites of bolide strikes, such as
4300-594: The division of Alta California at 36 degrees, 30 minutes, the line of the Missouri Compromise . Instead, the passing of the Compromise of 1850 enabled California to be admitted to the Union as a free state , preventing the southern half of California from becoming its own separate slave state . Subsequently, Californians (dissatisfied with inequitable taxes and land laws) and pro-slavery Southerners in
4386-409: The fault (called a piercing point ). In practice, it is usually only possible to find the slip direction of faults, and an approximation of the heave and throw vector. The two sides of a non-vertical fault are known as the hanging wall and footwall . The hanging wall occurs above the fault plane and the footwall occurs below it. This terminology comes from mining: when working a tabular ore body,
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#17328007119644472-459: The fault is the horizontal component, as in "Throw up and heave out". The vector of slip can be qualitatively assessed by studying any drag folding of strata, which may be visible on either side of the fault. Drag folding is a zone of folding close to a fault that likely arises from frictional resistance to movement on the fault. The direction and magnitude of heave and throw can be measured only by finding common intersection points on either side of
4558-465: The fault movement. Faults are mainly classified in terms of the angle that the fault plane makes with the Earth's surface, known as the dip , and the direction of slip along the fault plane. Based on the direction of slip, faults can be categorized as: In a strike-slip fault (also known as a wrench fault , tear fault or transcurrent fault ), the fault surface (plane) is usually near vertical, and
4644-496: The fault place the length around 30–50 km (19–31 mi), while interpretations including the NIFZ place the length at 170 km (110 mi). There are not many earthquakes associated with the fault, however a magnitude 6–6.5 may have struck on the fault in 1862. The fault runs very near to populated areas when offshore, hence there is high potential for infrequent large and damaging earthquakes. Southern California lies along
4730-671: The fault, earthquakes nearing magnitude 7 have a recurrence interval between 700±400 and 2,000 years. Scenarios modeling a magnitude 6.9 earthquake predict peak ground acceleration will reach 0.55 g in San Diego, and 0.35 g in Tijuana . Downtown San Diego and Mission Bay will experience liquefaction , while Mt. Soledad may experience landslides . Coastal areas such as La Jolla and Point Loma may experience localized coastal bluff failures, and submarine canyons may have landslides which trigger tsunamis . Other studies link
4816-429: The first decade of the 21st century, droughts and wildfires have increased in frequency as a result of climate change . Southern California consists of one of the more varied collections of geologic, topographic, and natural ecosystem landscapes in a diversity outnumbering other major regions in the state and country. The region spans from Pacific Ocean islands , shorelines , beaches, and coastal plains , through
4902-749: The five most populous in the state, and are among the top 15 most populous counties in the United States. The motion picture , television and music industry are centered in the Los Angeles area in Southern California. Hollywood , a district of Los Angeles, gives its name to the American motion picture industry, which is synonymous with the neighborhood name. Headquartered in Southern California are The Walt Disney Company (which owns ABC ), Sony Pictures , Universal Pictures , MGM , Paramount Pictures , and Warner Bros . Universal, Warner Bros., and Sony also run major record companies. Southern California
4988-428: The footwall moves laterally either left or right with very little vertical motion. Strike-slip faults with left-lateral motion are also known as sinistral faults and those with right-lateral motion as dextral faults. Each is defined by the direction of movement of the ground as would be seen by an observer on the opposite side of the fault. A special class of strike-slip fault is the transform fault when it forms
5074-531: The footwall. The dip of most normal faults is at least 60 degrees but some normal faults dip at less than 45 degrees. A downthrown block between two normal faults dipping towards each other is a graben . A block stranded between two grabens, and therefore two normal faults dipping away from each other, is a horst . A sequence of grabens and horsts on the surface of the Earth produces a characteristic basin and range topography . Normal faults can evolve into listric faults, with their plane dip being steeper near
5160-429: The geometric gap, and depending on its rheology , the hanging wall might fold and slide downwards into the gap and produce rollover folding , or break into further faults and blocks which fil in the gap. If faults form, imbrication fans or domino faulting may form. A reverse fault is the opposite of a normal fault—the hanging wall moves up relative to the footwall. Reverse faults indicate compressive shortening of
5246-491: The implied mechanism of deformation. A fault that passes through different levels of the lithosphere will have many different types of fault rock developed along its surface. Continued dip-slip displacement tends to juxtapose fault rocks characteristic of different crustal levels, with varying degrees of overprinting. This effect is particularly clear in the case of detachment faults and major thrust faults . The main types of fault rock include: In geotechnical engineering ,
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#17328007119645332-464: The largest faults on Earth and give rise to the largest earthquakes. A fault which has a component of dip-slip and a component of strike-slip is termed an oblique-slip fault . Nearly all faults have some component of both dip-slip and strike-slip; hence, defining a fault as oblique requires both dip and strike components to be measurable and significant. Some oblique faults occur within transtensional and transpressional regimes, and others occur where
5418-401: 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
5504-582: The lightly populated "cow counties" of Southern California attempted three times in the 1850s to achieve a separate statehood or territorial status separate from Northern California . The last attempt, the Pico Act of 1859, was passed by the California State Legislature and signed by State Governor John B. Weller . It was approved overwhelmingly by nearly 75 percent of voters to form the proposed Territory of Colorado . This territory
5590-408: The miner stood with the footwall under his feet and with the hanging wall above him. These terms are important for distinguishing different dip-slip fault types: reverse faults and normal faults. In a reverse fault, the hanging wall displaces upward, while in a normal fault the hanging wall displaces downward. Distinguishing between these two fault types is important for determining the stress regime of
5676-550: The more urban region) that have been left undeveloped. It is the third most populated megalopolis in the United States, after the Great Lakes megalopolis and the Northeast megalopolis . Much of Southern California is famous for its large, spread-out, suburban communities and use of automobiles and highways. The dominant areas are Los Angeles, Orange County , San Diego , and Riverside – San Bernardino , each of which are
5762-435: The most common. With the passage of time, a regional reversal between tensional and compressional stresses (or vice-versa) might occur, and faults may be reactivated with their relative block movement inverted in opposite directions to the original movement (fault inversion). In such a way, a normal fault may therefore become a reverse fault and vice versa. In a normal fault, the hanging wall moves downward, relative to
5848-494: The opposite direction. These faults may be accompanied by rollover anticlines (e.g. the Niger Delta Structural Style). All faults have a measurable thickness, made up of deformed rock characteristic of the level in the crust where the faulting happened, of the rock types affected by the fault and of the presence and nature of any mineralising fluids . Fault rocks are classified by their textures and
5934-412: The right time for—and type of— igneous differentiation . At a given time differentiated magmas would burst violently out of the fault-traps and head to shallower places in the crust where porphyry copper deposits would be formed. As faults are zones of weakness, they facilitate the interaction of water with the surrounding rock and enhance chemical weathering . The enhanced chemical weathering increases
6020-423: The rigidity of the constituent rocks, the two sides of a fault cannot always glide or flow past each other easily, and so occasionally all movement stops. The regions of higher friction along a fault plane, where it becomes locked, are called asperities . Stress builds up when a fault is locked, and when it reaches a level that exceeds the strength threshold, the fault ruptures and the accumulated strain energy
6106-455: The size of the weathered zone and hence creates more space for groundwater . Fault zones act as aquifers and also assist groundwater transport. Southern California Southern California (commonly shortened to SoCal ) is a geographic and 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 populous urban agglomeration in
6192-471: The sole county to vote for the GOP, with Orange County having been Democrat since 2012. Southern California is one of the largest economies in the United States. It is dominated by, and heavily dependent upon, the abundance of petroleum, as opposed to other regions where automobiles are not nearly as dominant, due to the vast majority of transport that runs on this fuel. Southern California is famous for tourism and
6278-584: The southern section of the San Andreas (in the Palm Springs region, which has not ruptured in ~400 years), the entire Southern California portion of the San Andreas Fault is ready to produce a powerful earthquake in the near future. Notable faults capable of large magnitude events include the San Jacinto Fault (a splay of the San Andreas that runs directly under the I-10 & I-215 interchange),
6364-470: The state, formed by the northern boundaries of San Luis Obispo , Kern , and San Bernardino counties, which are not exactly a straight line. Another definition for Southern California uses Point Conception and the Tehachapi Mountains as the northern geographical barriers, especially when defining California's bioregions . In this definition, Owens Valley and Death Valley are part of
6450-404: The strain rate is too great. Slip is defined as the relative movement of geological features present on either side of a fault plane. A fault's sense of slip is defined as the relative motion of the rock on each side of the fault concerning the other side. In measuring the horizontal or vertical separation, the throw of the fault is the vertical component of the separation and the heave of
6536-416: The stratigraphic sequence is known as a ramp . Typically, thrust faults move within formations by forming flats and climbing up sections with ramps. This results in the hanging wall flat (or a portion thereof) lying atop the foot wall ramp as shown in the fault-bend fold diagram. Thrust faults form nappes and klippen in the large thrust belts. Subduction zones are a special class of thrusts that form
6622-400: The surface, then shallower with increased depth, with the fault plane curving into the Earth. They can also form where the hanging wall is absent (such as on a cliff), where the footwall may slump in a manner that creates multiple listric faults. The fault panes of listric faults can further flatten and evolve into a horizontal or near-horizontal plane, where slip progresses horizontally along
6708-417: The top eight largest cities in the United States. In Southern California, there are also 14 cities with more than 200,000 residents and 48 cities over 100,000 residents. Many of Southern California's most developed cities lie along or in close proximity to the coast, with the exception of San Bernardino and Riverside. Southern California has drifted left since 2004, and is solidly Democrat. Kern County remains
6794-582: The vicinity. In California, for example, new building construction has been prohibited directly on or near faults that have moved within the Holocene Epoch (the last 11,700 years) of the Earth's geological history. Also, faults that have shown movement during the Holocene plus Pleistocene Epochs (the last 2.6 million years) may receive consideration, especially for critical structures such as power plants, dams, hospitals, and schools. Geologists assess
6880-429: The world's busiest general aviation airport; major commercial airports at San Bernardino , Orange County , Bakersfield , Ontario , Burbank , and Long Beach ; and numerous smaller commercial and general aviation airports. Six of the seven lines of the commuter rail system, Metrolink , run out of Downtown Los Angeles, connecting Los Angeles, Ventura , San Bernardino, Riverside, Orange, and San Diego counties with
6966-435: The world's largest action sports events, including the X Games , Boost Mobile Pro , and the U.S. Open of Surfing , are held in Southern California. The region is also important to the world of yachting with premier events including the annual Transpacific Yacht Race , or Transpac , from Los Angeles to Hawaii. San Diego Yacht Club hosted the three America's Cup races from 1988 to 1995. The first modern-era triathlon
7052-528: Was grouped with other counties of the San Joaquin Valley , California's central agricultural valley. Southern California consists of a heavily developed urban environment, home to some of the largest urban areas in the state, along with the Deserts of California (part of which was even proposed to become a new county due to cultural, economic and geographic differences relative to the rest of
7138-533: Was held in San Diego's Mission Bay in 1974. Since then, Southern California, and San Diego in particular, have become a mecca for triathlon and multi-sport racing, products, and culture. Southern California has multiple sports franchises and networks, such as Fox Sports Net . Many of these locals and tourists frequent the Southern California coast for its beaches. Some of Southern California's most popular beaches are Malibu , Laguna Beach , La Jolla , Manhattan Beach , and Hermosa Beach . Southern California
7224-546: Was high in the Bakersfield-Kern County , Santa Maria , and San Luis Obispo areas. Most of Southern California has a Mediterranean -like climate, with warm and dry summers, mild and wet winters, where cool weather and freezing temperatures are rare. Southern California contains other types of climates, including semi-arid , desert and mountain , with infrequent rain and many sunny days. Summers are hot or warm, and dry, while winters are mild, and rainfall
7310-698: Was the name of a proposed new state which failed to get on the 2018 California ballot. The ballot measure proposed splitting the existing state into three parts. In December 2020, during the COVID-19 pandemic , the state government led by Governor Gavin Newsom divided the state into five regions for the purpose of issuing stay-at-home orders. The Southern California region consisted of the following counties: Imperial , Inyo , Los Angeles , Mono , Orange , Riverside , San Bernardino , San Diego , San Luis Obispo , Santa Barbara , and Ventura . However, Kern County
7396-773: Was to include a portion of the much larger Tulare County and all of San Luis Obispo County . The proposal was sent to Washington, D.C. , with a strong advocate in Senator Milton Latham . However, the secession crisis following the election of Abraham Lincoln in 1860 and the subsequent American Civil War led to the proposal never coming to a vote. In 1900, the Los Angeles Times defined Southern California as including "the seven counties of Los Angeles, San Bernardino, Orange, Riverside, San Diego, Ventura, and Santa Barbara." This definition left out San Luis Obispo and Kern counties. Southern California
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