1.
San Andreas Lake
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San Andreas Lake is a reservoir adjacent to the San Francisco Peninsula cities of Millbrae and San Bruno in San Mateo County, California. It is situated directly on the San Andreas Fault, which is named after the valley it is in, the next day they reached a Laguna Grande which today is covered by the Upper Crystal Springs Reservoir. The campsite is marked by California Historical Marker No.94 Portola Expedition Camp, located at Crystal Springs Dam and they camped here a second time on November 12, on their return trip. De Anza returned to Monterey via the Cañada de San Andrés, originally a small natural sag pond, the lake was expanded by the construction of a 100 foot high earth dam in 1868. The dam survived the 1906 earthquake despite the fact that the fault runs directly under the dam, in 1895, Professor Andrew Lawson of the University of California, Berkeley, conferred the name of the lake on the earthquake fault he discovered in its vicinity. San Mateo Creek once hosted coho salmon as evidenced by specimens collected by Professor Alexander Agassiz of Harvard University in the 1850s and 1860s, since the lake is a public water source, it is closed to the public. However, hikers and bicyclists may travel along the shores of the lake on a paved trail that runs just west of Skyline Boulevard from San Bruno Avenue to Millbrae Avenue. A connecting trail, called the Sawyer Camp Trail, crosses the valley on the San Andreas Dam. This 6 mile trail eventually reaches the shores of the Lower Crystal Springs reservoir. List of lakes in California List of lakes in the San Francisco Bay Area U. S. Geological Survey Geographic Names Information System, San Andreas Lake San Andreas Lake San Andreas Fault in the Bay Area
San Andreas Lake
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San Andreas Lake
2.
United States
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Forty-eight of the fifty states and the federal district are contiguous and located in North America between Canada and Mexico. The state of Alaska is in the northwest corner of North America, bordered by Canada to the east, the state of Hawaii is an archipelago in the mid-Pacific Ocean. The U. S. territories are scattered about the Pacific Ocean, the geography, climate and wildlife of the country are extremely diverse. At 3.8 million square miles and with over 324 million people, the United States is the worlds third- or fourth-largest country by area, third-largest by land area. It is one of the worlds most ethnically diverse and multicultural nations, paleo-Indians migrated from Asia to the North American mainland at least 15,000 years ago. European colonization began in the 16th century, the United States emerged from 13 British colonies along the East Coast. Numerous disputes between Great Britain and the following the Seven Years War led to the American Revolution. On July 4,1776, during the course of the American Revolutionary War, the war ended in 1783 with recognition of the independence of the United States by Great Britain, representing the first successful war of independence against a European power. The current constitution was adopted in 1788, after the Articles of Confederation, the first ten amendments, collectively named the Bill of Rights, were ratified in 1791 and designed to guarantee many fundamental civil liberties. During the second half of the 19th century, the American Civil War led to the end of slavery in the country. By the end of century, the United States extended into the Pacific Ocean. The Spanish–American War and World War I confirmed the status as a global military power. The end of the Cold War and the dissolution of the Soviet Union in 1991 left the United States as the sole superpower. The U. S. is a member of the United Nations, World Bank, International Monetary Fund, Organization of American States. The United States is a developed country, with the worlds largest economy by nominal GDP. It ranks highly in several measures of performance, including average wage, human development, per capita GDP. While the U. S. economy is considered post-industrial, characterized by the dominance of services and knowledge economy, the United States is a prominent political and cultural force internationally, and a leader in scientific research and technological innovations. In 1507, the German cartographer Martin Waldseemüller produced a map on which he named the lands of the Western Hemisphere America after the Italian explorer and cartographer Amerigo Vespucci
United States
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Native Americans meeting with Europeans, 1764
United States
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Flag
United States
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The signing of the
Mayflower Compact, 1620.
United States
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The
Declaration of Independence: the
Committee of Five presenting their draft to the
Second Continental Congress in 1776
3.
California
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California is the most populous state in the United States and the third most extensive by area. Located on the western coast of the U. S, California is bordered by the other U. S. states of Oregon, Nevada, and Arizona and shares an international border with the Mexican state of Baja California. Los Angeles is Californias most populous city, and the second largest after New York City. The Los Angeles Area and the San Francisco Bay Area are the nations second- and fifth-most populous urban regions, California also has the nations most populous county, Los Angeles County, and its largest county by area, San Bernardino County. The Central Valley, an agricultural area, dominates the states center. What is now California was first settled by various Native American tribes before being explored by a number of European expeditions during the 16th and 17th centuries, the Spanish Empire then claimed it as part of Alta California in their New Spain colony. The area became a part of Mexico in 1821 following its war for independence. The western portion of Alta California then was organized as the State of California, the California Gold Rush starting in 1848 led to dramatic social and demographic changes, with large-scale emigration from the east and abroad with an accompanying economic boom. If it were a country, California would be the 6th largest economy in the world, fifty-eight percent of the states economy is centered on finance, government, real estate services, technology, and professional, scientific and technical business services. Although it accounts for only 1.5 percent of the states economy, the story of Calafia is recorded in a 1510 work The Adventures of Esplandián, written as a sequel to Amadis de Gaula by Spanish adventure writer Garci Rodríguez de Montalvo. The kingdom of Queen Calafia, according to Montalvo, was said to be a land inhabited by griffins and other strange beasts. This conventional wisdom that California was an island, with maps drawn to reflect this belief, shortened forms of the states name include CA, Cal. Calif. and US-CA. Settled by successive waves of arrivals during the last 10,000 years, various estimates of the native population range from 100,000 to 300,000. The Indigenous peoples of California included more than 70 distinct groups of Native Americans, ranging from large, settled populations living on the coast to groups in the interior. California groups also were diverse in their organization with bands, tribes, villages. Trade, intermarriage and military alliances fostered many social and economic relationships among the diverse groups, the first European effort to explore the coast as far north as the Russian River was a Spanish sailing expedition, led by Portuguese captain Juan Rodríguez Cabrillo, in 1542. Some 37 years later English explorer Francis Drake also explored and claimed a portion of the California coast in 1579. Spanish traders made unintended visits with the Manila galleons on their trips from the Philippines beginning in 1565
California
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A forest of redwood trees in
Redwood National Park
California
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Flag
California
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Mount Shasta
California
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Aerial view of the
California Central Valley
4.
San Francisco
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San Francisco, officially the City and County of San Francisco, is the cultural, commercial, and financial center of Northern California. It is the birthplace of the United Nations, the California Gold Rush of 1849 brought rapid growth, making it the largest city on the West Coast at the time. San Francisco became a consolidated city-county in 1856, after three-quarters of the city was destroyed by the 1906 earthquake and fire, San Francisco was quickly rebuilt, hosting the Panama-Pacific International Exposition nine years later. In World War II, San Francisco was a port of embarkation for service members shipping out to the Pacific Theater. Politically, the city votes strongly along liberal Democratic Party lines, San Francisco is also the headquarters of five major banking institutions and various other companies such as Levi Strauss & Co. Dolby, Airbnb, Weebly, Pacific Gas and Electric Company, Yelp, Pinterest, Twitter, Uber, Lyft, Mozilla, Wikimedia Foundation, as of 2016, San Francisco is ranked high on world liveability rankings. The earliest archaeological evidence of habitation of the territory of the city of San Francisco dates to 3000 BC. Upon independence from Spain in 1821, the became part of Mexico. Under Mexican rule, the system gradually ended, and its lands became privatized. In 1835, Englishman William Richardson erected the first independent homestead, together with Alcalde Francisco de Haro, he laid out a street plan for the expanded settlement, and the town, named Yerba Buena, began to attract American settlers. Commodore John D. Sloat claimed California for the United States on July 7,1846, during the Mexican–American War, montgomery arrived to claim Yerba Buena two days later. Yerba Buena was renamed San Francisco on January 30 of the next year, despite its attractive location as a port and naval base, San Francisco was still a small settlement with inhospitable geography. The California Gold Rush brought a flood of treasure seekers, with their sourdough bread in tow, prospectors accumulated in San Francisco over rival Benicia, raising the population from 1,000 in 1848 to 25,000 by December 1849. The promise of fabulous riches was so strong that crews on arriving vessels deserted and rushed off to the gold fields, leaving behind a forest of masts in San Francisco harbor. Some of these approximately 500 abandoned ships were used at times as storeships, saloons and hotels, many were left to rot, by 1851 the harbor was extended out into the bay by wharves while buildings were erected on piles among the ships. By 1870 Yerba Buena Cove had been filled to create new land, buried ships are occasionally exposed when foundations are dug for new buildings. California was quickly granted statehood in 1850 and the U. S. military built Fort Point at the Golden Gate, silver discoveries, including the Comstock Lode in Nevada in 1859, further drove rapid population growth. With hordes of fortune seekers streaming through the city, lawlessness was common, and the Barbary Coast section of town gained notoriety as a haven for criminals, prostitution, entrepreneurs sought to capitalize on the wealth generated by the Gold Rush
San Francisco
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San Francisco and the
Golden Gate Bridge from
Marin Headlands
San Francisco
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Mission San Francisco de Asís (Mission Dolores)
San Francisco
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1853
United States Coast Survey Map
San Francisco
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Francis Samuel Marryat, Hilltop of San Francisco, California, Looking toward the Bay, 1849. M.& N. Hanhart Chromolithograph
5.
Calaveras Fault
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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 aseismic creep, the last large event was the 1984 Morgan Hill event and the last moderate earthquake was the 2007 Alum Rock event. It is believed to link with the Hayward fault, as well as the West Napa Fault and it passes through or near the cities of Alamo, Danville, San Ramon, Dublin, Pleasanton, Sunol, Milpitas, San Jose, Gilroy, and Hollister. To the east of the Hayward-Rodgers Creek fault, the Calaveras fault extends 123 km, splaying from the San Andreas fault near Hollister and terminating at Danville at its northern end. It runs east of the San Andreas, diverging from it in the vicinity of Hollister, California, between the San Andreas Fault and the Calaveras Fault lies the Hayward Fault, which diverges from the Calaveras Fault east of San Jose, California. To the east lies the Clayton-Marsh Creek-Greenville Fault and these four fault structures are some of the major faults in California at the latitude of San Francisco. All are right lateral-moving strike-slip faults, the Calaveras Fault was named for Calaveras Creek in Santa Clara County east of San Jose where it was first identified. Calaveras is also the name of a California county in the foothills of the Sierra Nevada mountains, some 100 miles east of Santa Clara County, far from the Calaveras Fault. Some of the cities which the Calaveras Fault passes through or near are, Alamo, Danville, San Ramon, Dublin, Pleasanton, Sunol, Milpitas, San Jose, Gilroy, and Hollister. The West Napa Fault in Napa County is believed to be a continuation of the Calaveras Fault north of the Carquinez Strait, between the faults lies an area of minor faults aligned en echelon known as the Contra Costa Shear Zone. Stresses are also produced by offset and converging slip-strike motions between the Calaveras and Clayton-Marsh Creek-Greenville Fault that continue to elevate Mount Diablo, the Pacific Plate is a major section of the Earths crust, gradually expanding by the eruption of magma along the East Pacific Rise to the southeast. It is also being subducted far to the northwest into the Aleutian Trench under the North American Plate well north of San Francisco, in California, the plate is sliding northwestward along a transform boundary, the San Andreas Fault, toward the subduction zone. At the same time, the North American Plate is moving southwestward, the Calaveras Fault shares the same relative motions of the San Andreas. A number of magnitude 6 earthquakes have been recorded on the fault throughout recorded history, the most recent of these was a magnitude 6.2 earthquake near Morgan Hill in 1984. A magnitude 5.6 earthquake occurred on the Calaveras Fault on October 30,2007 at 20,04 PDT, near Alum Rock. Prior to the 2014 South Napa earthquake, it was the most powerful quake to hit the Bay Area since the Loma Prieta earthquake of 1989, recent assessments suggest that the northern Calaveras fault may be more likely to fail in the next few decades than previously thought. Bernal Subbasin Tesla Fault M6.9 Earthquake on the Calaveras Fault — Southern California Earthquake Center ABAG shaking hazard maps
Calaveras Fault
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For recent activity in the region shown on this map see the USGS map for this location. The "live" maps will also show all of the names of faults shown on the map as you rollover with the cursor.
6.
Hayward Fault Zone
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The Hayward Fault Zone is a geologic fault zone capable of generating significantly destructive earthquakes. This fault is about 74 mi long, situated mainly along the base of the hills on the east side of San Francisco Bay. It runs through densely populated areas, including the cities of Richmond, El Cerrito, Berkeley, Oakland, San Leandro, Hayward, Union City, Fremont, and San Jose, in order from north-to-south. The Hayward Fault is parallel to its more famous westerly neighbor, the San Andreas Fault, to the south of the Hayward lies the Calaveras Fault. In 2007 the Hayward Fault was discovered to merge with the Calaveras Fault east of San Jose at a depth of 4 miles, some geologists have suggested that the Southern Calaveras should be renamed as the Southern Hayward. Further discussion may be found below in the subsection on Rodgers Creek Fault, another fault further north, the Maacama Fault, is also considered to be part of the Hayward Fault subsystem. The Pacific Plate is a section of the Earths crust. It is also being subducted far to the northwest into the Aleutian Trench, in California, the plate is sliding northwestward along a transform boundary, the San Andreas Fault, toward the subduction zone. At the same time, the North American Plate is moving southwestward, the Hayward Fault shares the same relative motions of the San Andreas. As with portions of other faults, an extent of the Hayward Fault trace is formed from a narrow complex zone of deformation which can span hundreds of feet in width. The Hayward Fault is one of the faults in this diffuse zone, along with the Calaveras Fault to the east. The complete fault zone, including the Rodgers Creek fault, is divided by seismologists into three segments – Rodgers Creek, Northern Hayward, and Southern Hayward and it is expected that these segments may fail singly or in adjacent pairs, creating earthquakes of varying magnitude. The various ABAG maps shown below represent some of the likely possible combinations. An alternate prior hypothesis suggested that the Hayward Fault and Rodgers Creek Fault were probably connected by a series of en echelon fault strands beneath San Pablo Bay, the new finding means that the Rodgers-Hayward system together could produce a quake with a magnitude as high as 7.2. It is also considered possible that a seismic event on either fault may involve movement on the other, either concurrently or within an interval of up to several months. The Association of Bay Area Governments has prepared ground shaking maps that include a possible concurrent scenario and it has been suggested that the name Rodgers Creek Fault be retired and that the entire 118 mi fault be known as the Hayward Fault. The Calaveras Fault is considered to be continuous from the Sunol area south to Hollister and it was long believed that there was no connection between the Hayward Fault and the Calaveras. Recent geological studies suggest that the two faults may be connected, the largest quake on the Hayward Fault in recorded history occurred in 1868, with an estimated magnitude of 7.0
Hayward Fault Zone
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USGS map showing faults that span the Pacific–North America plate boundary.
Hayward Fault Zone
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San Francisco Bay region earthquake probability
Hayward Fault Zone
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USGS satellite photo of the San Francisco Bay Area. Light gray areas are heavily urbanized regions
Hayward Fault Zone
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The effects of 15 years of
fault creep on a curb in
Fremont.
7.
Elsinore Fault Zone
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The Elsinore Fault Zone is a large right-lateral strike-slip geological fault structure in Southern California. The fault is part of the split of the San Andreas fault system and is one of the largest. The Elsinore fault zone, not including Whittier, Chino, and it is estimated that this zone is capable of producing a quake of 6. 5–7.5 MW. The projected interval between major events is 250 years. The last major event on the main Elsinore fault was in 1910 with a 6 MW earthquake centered just northwest of the city of Lake Elsinore. The fault runs from the mountainous Peninsular Ranges region between El Centro and San Diego, northwest to the Chino Hills range and Chino Hills, on the southern end of the fault zone is the southeastern extension of the Elsinore fault zone, the Laguna Salada Fault. At its northern end, the Elsinore fault zone splits into two segments, the Chino Fault and the Whittier Fault, Geology of a Portion of the Elsinore Fault Zone, California. State of California, Department of Natural Resources, Division of Mines, Geology and mineral resources of San Diego County, California. California Division of Mines and Geology, m6.5 Earthquake on the Elsinore Fault – Southern California Earthquake Center
Elsinore Fault Zone
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California Coast, Los Angeles to San Diego Bay. Elsinore Fault Zone is labeled in the center running along the Santa Ana Mountains. NASA photo, 2008
8.
San Jacinto Fault Zone
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The San Jacinto Fault Zone 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 zone in the area. Together they relieve the majority of the stress between the Pacific and North American tectonic plates, 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 risk and was assigned a probability for the occurrence of a large rupture for the thirty-year period starting in 1995. The recurrence interval for a series of earthquakes starting in 1899 was 18,5,14,5,12,14. The San Jacinto Fault Zone and the San Andreas Fault accommodate up to 80% of the rate between the North American and Pacific plates. The locations of earthquakes before the 1954 Arroyo Salada earthquake are not precisely known, a 1995 report by the Working Group on California Earthquake Probabilities identified seven individual segments of the SJFZ. The group consisted of more than three dozen seismologists, including Keiiti Aki and C, allin Cornell, and was organized by the Southern California Earthquake Center for the USGS and the California Office of Emergency Services. Both these fault zones were grouped together as having adequate paleoseismic data to assign conditional probabilities for future damaging earthquakes, the original Working Group in 1988 had identified five segments of the fault zone. From north to south, the segments were labeled the San Bernardino Valley, San Jacinto Valley, Anza, Borrego Mountain, and Superstition Hills. The 1995 group then added the Coyote Creek and Superstition Mountain segments, defined the Anza segment to include the Clark and Casa Loma faults, thirty year probabilities for segment-rupturing earthquakes were estimated using three separate models then a preferred weighted result was presented for each segment. The Coyote Creek, Superstition Mountain, and Superstition Hills segments received first time estimates, the northernmost primary strand of the SJFZ is the Claremont strand. It spans a total of 75 km, from its endpoint in Cajon Pass to its southern endpoint in the San Jacinto Valley. A series of earthquakes affected this area in the 1890s. The San Jacinto Valley is a 25 km long, ~4 km wide valley that was formed by extension in a region of overlap between two parallel strands of the SJFZ. The valley is bounded by the Claremont strand to the northwest, the Clark strand, which is separated from the Casa Loma by a small compressional step in the city of Hemet, continues southeastward out of the valley. This area was damaged by the historic earthquakes of 1899 and 1918. The 1899 event is thought to have occurred within the valley, likely on the Casa Loma strand, while the 1988 Working Group included the Clark, Coyote Creek, and Buck Ridge faults, the 1995 Working Group limited the segment to just the 90 km Clark fault
San Jacinto Fault Zone
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California Coast, Los Angeles to San Diego Bay. Overlaid lines on this NASA photo (2008) identify the San Jacinto Fault Zone (right) parallel to the Elsinore Fault (left)
San Jacinto Fault Zone
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Map showing the San Jacinto Fault Zone outlined in red
San Jacinto Fault Zone
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ShakeMap showing the intensity of the 1968 Borrego Mountain earthquake
San Jacinto Fault Zone
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USGS ShakeMap of the second (stronger) mainshock in the November 1987 sequence
9.
Fault (geology)
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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 movement. Large faults within the Earths crust result from the action of tectonic forces. Energy release associated with movement on active faults is the cause of most earthquakes. A fault plane is the plane that represents the surface of a fault. A fault trace or fault line is the intersection of a plane with the ground surface. A fault trace is also the line commonly plotted on maps to represent a fault. Since faults do not usually consist of a single, clean fracture, the two sides of a non-vertical fault are known as the hanging wall and footwall. By definition, the wall occurs above the fault plane. This terminology comes from mining, when working a tabular ore body, because of friction and the rigidity of rocks, they cannot glide or flow past each other easily, and occasionally all movement stops. A fault in ductile rocks can also release instantaneously when the rate is too great. The energy released by instantaneous strain-release causes earthquakes, a common phenomenon along transform boundaries, slip is defined as the relative movement of geological features present on either side of a fault plane, and is a displacement vector. A faults sense of slip is defined as the motion of the rock on each side of the fault with respect to the other side. In practice, it is only possible to find the slip direction of faults. Based on direction of slip, faults can be categorized as, strike-slip. Dip-slip, offset is predominantly vertical and/or perpendicular to the fault trace, oblique-slip, combining significant strike and dip slip. The fault surface is usually vertical and the footwall moves either left or right or laterally with very little vertical motion. Strike-slip faults with left-lateral motion are known as sinistral faults. Those with right-lateral motion are known as dextral faults
Fault (geology)
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Large normal fault in
Triassic to
Lower Jurassic Blue Anchor Formation sediments near
Blue Anchor,
Somerset, UK, with several smaller normal faults in its hanging wall
Fault (geology)
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A fault in the Grands Causses as seen from
Bédarieux,
France. The left side moved down relative to the right side
Fault (geology)
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Microfault showing a
piercing point (the coin's diameter is 18 mm)
Fault (geology)
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The Piqiang Fault, a northwest trending strike-slip fault in the
Taklamakan Desert south of the
Tien Shan Mountains, China (40.3°N, 77.7°E)
10.
List of tectonic plates
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This is a list of tectonic plates on the Earths surface. Tectonic plates are pieces of Earths crust and uppermost mantle, together referred to as the lithosphere, the plates are around 100 km thick and consist of two principal types of material, oceanic crust and continental crust. The composition of the two types of crust differs markedly, with basaltic rocks dominating oceanic crust, while continental crust consists principally of lower-density felsic granitic rocks. Geologists generally agree that the tectonic plates currently exist on the Earths surface with roughly definable boundaries. Tectonic plates are sometimes subdivided into three fairly arbitrary categories, major plates, minor plates, and microplates and these plates comprise the bulk of the continents and the Pacific Ocean. For purposes of this list, a plate is any plate with an area greater than 20 million km2. For purposes of this list, a plate is any plate with an area less than 20 million km2. For purposes of this list, a microplate is any plate with a less than 1 million km2. Some models identify more minor plates within current orogens like the Apulian, Explorer, Gorda, there may or may not be scientific consensus as to whether such plates should be considered distinct portions of the crust, thus new research could change this list. A supercontinent is a landmass consisting of multiple continental cores, the following list of ancient cratons, microplates, plates, shields, terranes, and zones no longer exist as separate plates. Cratons are the oldest and most stable parts of the continental lithosphere, terranes may or may not have originated as independent microplates since a terrane may not contain the full thickness of the lithosphere
List of tectonic plates
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Basic geological regions of Australia, by age.
List of tectonic plates
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Global earthquake epicentres, 1963–1998
List of tectonic plates
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Map of chronostratigraphic divisions of India
11.
North American Plate
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The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, the Bahamas, extreme northeastern Russia, and parts of Iceland and the Azores. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia, the plate includes both continental and oceanic crust. The interior of the continental landmass includes an extensive granitic core called a craton. Along most of the edges of this craton are fragments of material called terranes. It is thought that much of North America west of the Rocky Mountains is composed of such terranes, the parallel Septentrional and Enriquillo-Plantain Garden faults, which run through the island of Hispaniola and bound the Gonâve Microplate, are also a part of the boundary. On the northerly boundary is a continuation of the Mid-Atlantic ridge called the Gakkel Ridge, the rest of the boundary in the far northwestern part of the plate extends into Siberia. On its western edge, the Farallon Plate has been subducting under the North American Plate since the Jurassic Period, the Juan de Fuca, Explorer, Gorda, Rivera, Cocos and Nazca plates are remnants of the Farallon Plate. The boundary along the Gulf of California is complex and it is generally accepted that a piece of the North American Plate was broken off and transported north as the East Pacific Rise propagated northward, creating the Gulf of California. A few hotspots are thought to exist below the North American Plate, the most notable hotspots are the Yellowstone, Raton, and Anahim hotspots. The Yellowstone and Anahim hotspots are thought to have first arrived during the Miocene period and are still geologically active, for the most part, the North American Plate moves in roughly a southwest direction away from the Mid-Atlantic Ridge. One recent study suggests that a convective current is propelling the plate. Geologic timeline of Western North America New Madrid Seismic Zone - an ancient intraplate fault zone within the North American Plate, notable as early as 1699 Notes
North American Plate
–
North American Plate
12.
Pacific Plate
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The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million square kilometres, it is the largest tectonic plate, the Pacific Plate contains an interior hot spot forming the Hawaiian Islands. Hillis and Müller are reported to consider the Birds Head Plate to be moving in unison with the Pacific Plate, bird considers them to be unconnected. The north-eastern side is a divergent boundary with the Explorer Plate, the Juan de Fuca Plate and the Gorda Plate forming respectively the Explorer Ridge, the Juan de Fuca Ridge and the Gorda Ridge. In the middle of the side is a transform boundary with the North American Plate along the San Andreas Fault. The south-eastern side is a divergent boundary with the Nazca Plate forming the East Pacific Rise, the southern side is a divergent boundary with the Antarctic Plate forming the Pacific-Antarctic Ridge. The Alpine Fault marks a boundary between the two plates, and further south the Indo-Australian Plate subducts under the Pacific Plate forming the Puysegur Trench. The southern part of Zealandia, which is to the east of this boundary, is the plates largest block of continental crust, the northern side is a convergent boundary subducting under the North American Plate forming the Aleutian Trench and the corresponding Aleutian Islands. The Pacific Plate is almost entirely oceanic crust, but it contains some continental crust in New Zealand, Baja California, the Pacific Plate has the distinction of showing one of the largest areal sections of the oldest members of seabed geology being entrenched into eastern Asian oceanic trenches. The oldest member disappearing by way of the Plate Tectonics cycle is early-Cretaceous, all maps of the Earths ocean floor geology show ages younger than 145 million years, only about 1/30 of the Earths 4.55 billion year history
Pacific Plate
–
Pacific Plate
13.
List of earthquakes
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The following is a list of earthquake lists, and of top earthquakes by magnitude and fatalities. This list is biased towards recent years due to development and widespread deployment of seismometers, also, records that were detailed enough to make magnitude estimates were not generally available before 1900. This list is a work in progress, information is likely to be changed. Please note, multiple countries could have the same earthquake listed, unless otherwise noted, magnitudes are reported on the Moment magnitude scale. This is a list or major earthquakes by the value of property losses directly attributable to the earthquake. Rank values are assigned based on inflation-adjusted comparison of property damage in US dollars, wherever possible, indirect and socioeconomic losses are excluded. Please note that damage estimates for particular earthquakes may vary through time as data becomes available
List of earthquakes
–
A
pie chart comparing the
seismic moment release of the three largest earthquakes for the hundred-year period from 1906 to 2005 with that for all earthquakes of magnitudes <6, 6 to 7, 7 to 8 and >8 for the same period
14.
1857 Fort Tejon earthquake
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The 1857 Fort Tejon earthquake occurred at about 8,20 am on January 9 in central and Southern California. 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, between Parkfield and Wrightwood. Though the shock was centered near Parkfield, the event is referred to as the Fort Tejon earthquake, 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. Accounts of the events varied widely, including the time of the main shock as well as foreshocks that were reported to have occurred at several locations earlier that morning. The Pacific Plate is moving relative to the Sierra Nevada-Great Valley Block of the North American Plate at about 38 millimeters per year. Paleoseismic studies have found evidence for many earthquakes in the last 3,000 years on this part of the San Andreas Fault. The earthquake ruptured a substantial portion of the southern San Andreas fault, the average slip along the fault was 4.5 meters, and a maximum offset of 9 meters was recorded in the Carrizo Plain area in southeastern San Luis Obispo County. With an estimated magnitude of 7.9, this was the last Big One in Southern California, the extreme southernmost portion of the San Andreas fault, which terminates near Bombay Beach at the Salton Sea, last ruptured in 1680. Surface faulting may have extended beyond the boundaries of the regularly acknowledged slip length, researchers recorded first and second-hand accounts of the ground crack, which was understood to be recent surface faulting and not just the topography of the existing rift. On the extreme end of the rupture zone, the surface cracking extended 80 kilometers north of Cholame into San Benito County. Evidence of uprooted and displaced trees south of Elizabeth Lake indicates surface faulting along a track that ran directly under three Jeffrey Pines. Two of the three trees examined were tilted in their extremity, while the upper portions remained relatively untilted. Tree ring dating confirmed that the trees had originated 10 and 25 years before 1857 and this is a frequently noted compensation of tree tilt. Seismologist Kerry Sieh determined that fault slip and the associated ground disturbance was the source of the mole track, the lack of standardized timekeeping during this period of Californias history contributed to some of the inaccurate reports of when the pre-shocks occurred. Local time was being used in 1857 and San Francisco would have been the locality with the most accurate time kept as it was a center of commerce, standard time was not followed until the 1880s, with the Pacific Time Zone being aligned with the 120th meridian. The differences in local times were substantial, with San Francisco at 122.43 W and San Diego at 117.10 W, at least one individual reported foreshock times that varied by as much as half an hour when speaking to two different newspapers. The firsthand reports were most abundant for the felt at 1,2, and 4 hours before the main shock which were later labeled the predawn, dawn. The predawn event shook residents of San Francisco, San Jose, the dawn shock was felt in those locales plus Fort Tejon and possibly the Carrizo Plain
1857 Fort Tejon earthquake
–
Parkfield
15.
1906 San Francisco earthquake
–
The 1906 San Francisco earthquake struck the coast of Northern California at 5,12 a. m. on April 18 with an estimated moment magnitude of 7.8 and a maximum Mercalli intensity of XI. Severe shaking was felt from Eureka on the North Coast to the Salinas Valley, devastating fires soon broke out in the city and lasted for several days. As a result, about 3,000 people died and over 80% of the city of San Francisco was destroyed, the events are remembered as one of the worst and deadliest natural disasters in the history of the United States. The death toll remains the greatest loss of life from a disaster in Californias history. The San Andreas Fault is a transform fault that forms part of the tectonic boundary between the Pacific Plate and the North American Plate. The strike-slip fault is characterized by mainly lateral motion in a dextral sense, the 1906 rupture propagated both northward and southward for a total of 296 miles. This fault runs the length of California from the Salton Sea in the south to Cape Mendocino in the north, the maximum observed surface displacement was about 20 feet, geodetic measurements show displacements of up to 28 feet. The 1906 earthquake preceded the development of the Richter magnitude scale by three decades. The most widely accepted estimate for the magnitude of the quake on the moment magnitude scale is 7.8. According to findings published in the Journal of Geophysical Research, severe deformations in the earths crust took place both before and after the earthquakes impact. Accumulated strain on the faults in the system was relieved during the earthquake, the main shock epicenter occurred offshore about 2 miles from the city, near Mussel Rock. Shaking was felt from Oregon to Los Angeles, and inland as far as central Nevada, a strong foreshock preceded the main shock by about 20 to 25 seconds. The strong shaking of the main shock lasted about 42 seconds, there were decades of minor earthquakes – more than at any other time in the historical record for northern California – before the 1906 quake. For years, the epicenter of the quake was assumed to be near the town of Olema, in the Point Reyes area of Marin County, because of evidence of the degree of local earth displacement. In the 1960s, a seismologist at UC Berkeley proposed that the epicenter was more likely offshore of San Francisco, at the time,375 deaths were reported, partly because hundreds of fatalities in Chinatown went ignored and unrecorded. The total number of deaths is uncertain today, and is estimated to be roughly 3,000 at minimum. Most of the deaths occurred in San Francisco itself, but 189 were reported elsewhere in the Bay Area, nearby cities, such as Santa Rosa and San Jose, in Monterey County, the earthquake permanently shifted the course of the Salinas River near its mouth. Where previously the river emptied into Monterey Bay between Moss Landing and Watsonville, it was diverted 6 miles south to a new channel just north of Marina
1906 San Francisco earthquake
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1906 San Francisco earthquake
1906 San Francisco earthquake
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USGS ShakeMap showing the earthquake's intensity.
1906 San Francisco earthquake
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Damaged houses on Howard Street
1906 San Francisco earthquake
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Burning of the
Mission District
16.
1957 San Francisco earthquake
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The 1957 San Francisco earthquake occurred on March 22 at 11,44,22 local time with a moment magnitude of 5.7 and a maximum Mercalli Intensity of VII. The shock was located in Northern California in the vicinity of the San Andreas Fault, there was both a foreshock and aftershock sequence that lasted through the month of June. Damage was considered minimal, but financial losses amounted to around US$1 million, the San Andreas Fault is a northwest-striking transform fault that accommodates motion between the Pacific and North American Plates. The Mendocino Triple Junction is an area of high seismicity, and marks its northern extremity at the Gorda Plate, three moderate events in the San Francisco Bay Area occurred on or near the San Andreas Fault in the early nineteenth-century. Eight foreshocks preceded the main event, the first motion method was used to determine the focal mechanism of the mainshock. It was found to be dissimilar from the 1906 earthquake, and instead showed oblique movement on a steeply-dipping thrust fault, the strike-slip component was minimal, only about half as much as the thrust component. Damage was non-structural and was limited to content within buildings and cracked plaster and was estimated at $1 million, the most significant effects were seen in the western portion of Daly City and in the Lake Merced area of San Francisco. The minimal losses were attributed to the duration and lack of high intensity shaking. The event was felt over an area of 12,000 square miles and its scientific value was reinforced because it was captured on 13 strong motion instruments. A maximum peak ground acceleration of 0. 13g was recorded in Golden Gate Park, – San Francisco Museum and Historical Society
1957 San Francisco earthquake
–
Santa Rosa
17.
1989 Loma Prieta earthquake
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The 1989 Loma Prieta earthquake occurred in Northern California on October 17 at 5,04 p. m. local time. With a moment magnitude of 6.9 and a maximum Mercalli intensity of IX, no surface faulting occurred, though a large number of other ground failures and landslides were present, especially in the Summit area of the Santa Cruz Mountains. Due to the coverage of the 1989 World Series, it became the first major earthquake in the United States that was broadcast live on national television. Andrew Lawson, a geologist from the University of California, Berkeley, had named the fault after the San Andreas Lake and later led an investigation into that event. The San Andreas Fault ruptured for a length of 290 mi during the 1906 shock, several long term forecasts for a large shock along the San Andreas Fault in that area had been made public prior to 1989 but the earthquake that transpired was not what had been anticipated. The 1989 Loma Prieta event originated on an undiscovered oblique-slip reverse fault that is located adjacent to the San Andreas Fault, since many forecasts had been presented for the region near Loma Prieta, seismologists were not taken by surprise by the October 1989 event. Two moderate shocks, referred to as the Lake Elsman earthquakes by the USGS, occurred in the Santa Cruz Mountains region in June 1988, each events aftershock sequence and effect on stress drop was closely examined, and their study indicated that the shocks affected the mainshocks rupture process. The June 27,1988, shock occurred with an intensity of VI. Its effects included broken windows in Los Gatos, and other damage in Holy City. Farther away from the Santa Cruz Mountains, pieces of concrete fell from a structure at the Sunnyvale Town Center. More moderate damage resulted from the August 8,1989, shock when chimneys were toppled in Cupertino, Los Gatos, other damage included cracked walls and foundations and broken underground pipes. At the office of the Los Gatos City Manager, a window that was cracked had also broken in the earlier shock. Also in Los Gatos, one man died when he exited a building through a window, the Loma Prieta earthquake was named for Loma Prieta Peak in the Santa Cruz Mountains, which lies just to the east of the mainshock epicenter. At sites with rocky terrain, the duration was shorter and the shaking was much less intense, the strong motion records also allowed for the causative fault to be determined – the rupture was related to the San Andreas Fault System. While a Mercalli Intensity of VIII covered a large swath of territory relatively close to the further to the north. At more than 44 miles distant, the San Francisco Bay Area recorded peak horizontal accelerations that were as high as 0. 26g, in a general way, the location of aftershocks of the event delineated the extent of the faulting, which extended about 24 miles in length. Because the rupture took place bilaterally, the duration of strong shaking was about half of what it would have been had it ruptured in one direction only, the duration of a typical M6.9 shock with a comparable rupture length would have been about twice as long. Gregory Beroza, a seismologist with Stanford University, made several distinctions regarding the 1906 and 1989 events, near Loma Prieta, the 1906 rupture was more shallow, had more strike-slip, and occurred on a fault that was near vertical
1989 Loma Prieta earthquake
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1989 Loma Prieta earthquake
1989 Loma Prieta earthquake
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Loma Prieta Peak in the Santa Cruz Mountains
1989 Loma Prieta earthquake
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USGS ShakeMaps showing similar intensity patterns for the June 1988 (left) and August 1989 events near
Lake Elsman in the
Santa Cruz Mountains
1989 Loma Prieta earthquake
18.
Parkfield earthquake
–
Parkfield earthquake is a name given to various large earthquakes that occurred in the vicinity of the town of Parkfield, California, United States. The San Andreas fault runs through town, and six successive magnitude 6 earthquakes occurred on the fault at unusually regular intervals. The most recent significant earthquake to occur happened on September 28,2004. Scientists with the USGS and UC Berkeley had predicted, with a 90 to 95% confidence level and this was known as the Parkfield Earthquake Prediction and the Parkfield Earthquake Experiment, conducted by the USGS. Attempts at predicting the quake continued until January 2001, but an earthquake of 5.5 magnitude or greater did not occur from 1985 until the 2004 quake. In June 2004, the USGS in partnership with the National Science Foundation began drilling a hole to house instruments to monitor the fault at depth. This action was a part of the San Andreas Fault Observatory at Depth program and this led to the prediction in 1984 of a similar event in 1993. The 6.0 magnitude primary shock in 2004 was the result of a movement of about 18 inches. There have been no indications found that could have used to predict this earthquake. Although well overdue, the probability of this occurring in 2004 has been estimated at about ten percent. The magnitude of the event was consistent with previous earthquakes in this region, substantial aftershocks continued for more than a week after the initial event, moving in a northwesterly progression. In early October, there was a cluster of earthquakes near Paso Robles near a parallel fault to the west. These may be in response to the transfer of stress to these faults after the release of stress at Parkfield, past earthquakes have also occurred to the east of Parkfield at about the same distance from the San Andreas fault near Coalinga and Avenal. In December 2004, seismologists at the University of California, Berkeley announced the discovery of subtle tremors near Cholame and this is in a region of the locked fault below the Parkfield episodes, last creating an 8.0 magnitude quake at Fort Tejon in 1857. These tremors were discovered using deep borehole seismometers that avoid surface noise and it is hoped that this new discovery may sometime inform scientists as to the degree of danger presented by known locked faults. It is not currently expected that this knowledge will be refined into a predictive tool. It is believed that this earthquake was preceded by a magnitude 6.0 foreshock that was centered at Parkfield
Parkfield earthquake
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Predicting the 2004 event for 1993
Parkfield earthquake
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Activity snapshot 35 hours after Sept 28, 2004 large earthquake.
19.
Transform fault
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A transform fault or transform boundary, is a type of fault whose relative motion is predominantly horizontal, in either a sinistral or dextral direction. Furthermore, transform faults end abruptly and are connected on both ends to other faults, ridges, or subduction zones, Transform faults are the only type of strike-slip fault that can be classified as a plate boundary. The new class of faults, called transform faults, produce slip in the direction from what one would surmise from the standard interpretation of an offset geological feature. Slip along transform faults does not increase the distance between the ridges it separates, the distance remains constant in earthquakes because the ridges are spreading centers. This hypothesis was confirmed in a study of the fault plane solutions that showed the slip on transform faults points in the opposite direction than classical interpretation would suggest, Transform faults are closely related to transcurrent faults, and are commonly confused. In addition, transform faults have equal deformation across the fault line, while transcurrent faults have greater displacement in the middle of the fault zone. Finally, transform faults can form a plate boundary, while transcurrent faults cannot. The effect of a fault is to strain, which can be caused by compression, extension. Transform faults specifically relieve strain by transporting the strain between ridges or subduction zones, Transform faults also act as the plane of weakness allowing for the splitting in rift zones. Transform faults are commonly found linking segments of mid-oceanic ridges or spreading centres and these mid-oceanic ridges are where new seafloor is constantly created through the upwelling of new basaltic magma. With new seafloor being pushed and pulled out, the older seafloor slowly slides away from the mid-oceanic ridges toward the continents, although separated only by tens of kilometers, this separation between segments of the ridges causes portions of the seafloor to push past each other in opposing directions. This lateral movement of seafloors past each other is where transform faults are currently active, Transform faults move differently than a strike-slip fault at the mid-oceanic ridge. Evidence of this can be found in paleomagnetic striping on the seafloor, a paper written by Gerya theorizes that the creation of the transform faults between the ridges of the mid-oceanic ridge is attributed to rotated and stretched sections of the mid-oceanic ridge. This occurs over a period of time with the spreading center or ridge slowly deforming from a straight line to a curved line. Finally, fracturing along these planes forms transform faults, as this takes place, the fault changes from a normal fault with extensional stress to a strike slip fault with lateral stress. In the study done by Bonatti & Crane, peridotite and gabbro rocks were discovered in the edges of the transform ridges and these rocks are created deep inside the Earth’s mantle and then rapidly exhumed to the surface. This evidence helps to prove that new seafloor is being created at the mid-oceanic ridges, as previously stated, active transform faults are between two tectonic structures or faults. Fracture zones represent the active transform fault lines, which have since passed the active transform zone and are being pushed toward the continents
Transform fault
–
Transform fault
Transform fault
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Transform fault (the red lines)
Transform fault
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Transcurrent fault
Transform fault
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The
Southern Alps rise dramatically beside the
Alpine Fault on
New Zealand 's
West Coast. About 500 kilometres (300 mi) long; northwest at top.
20.
Tectonic movement
–
The theoretical model builds on the concept of continental drift developed during the first few decades of the 20th century. The geoscientific community accepted plate-tectonic theory after seafloor spreading was validated in the late 1950s, the lithosphere, which is the rigid outermost shell of a planet, is broken up into tectonic plates. The Earths lithosphere is composed of seven or eight major plates, where the plates meet, their relative motion determines the type of boundary, convergent, divergent, or transform. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along plate boundaries. The relative movement of the plates typically ranges from zero to 100 mm annually, tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere, each topped by its own kind of crust. Along convergent boundaries, subduction carries plates into the mantle, the material lost is balanced by the formation of new crust along divergent margins by seafloor spreading. In this way, the surface of the lithosphere remains the same. This prediction of plate tectonics is also referred to as the conveyor belt principle, earlier theories, since disproven, proposed gradual shrinking or gradual expansion of the globe. Tectonic plates are able to move because the Earths lithosphere has greater strength than the underlying asthenosphere. Lateral density variations in the result in convection. Plate movement is thought to be driven by a combination of the motion of the seafloor away from the ridge and drag, with downward suction. Another explanation lies in the different forces generated by forces of the Sun. The relative importance of each of these factors and their relationship to other is unclear. The outer layers of the Earth are divided into the lithosphere and asthenosphere and this is based on differences in mechanical properties and in the method for the transfer of heat. Mechanically, the lithosphere is cooler and more rigid, while the asthenosphere is hotter, in terms of heat transfer, the lithosphere loses heat by conduction, whereas the asthenosphere also transfers heat by convection and has a nearly adiabatic temperature gradient. The key principle of plate tectonics is that the lithosphere exists as separate and distinct tectonic plates, Plate motions range up to a typical 10–40 mm/year, to about 160 mm/year. The driving mechanism behind this movement is described below, tectonic lithosphere plates consist of lithospheric mantle overlain by either or both of two types of crustal material, oceanic crust and continental crust. Average oceanic lithosphere is typically 100 km thick, its thickness is a function of its age, as passes, it conductively cools
Tectonic movement
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Remnants of the
Farallon Plate, deep in Earth's mantle. It is thought that much of the plate initially went under North America (particularly the western United States and southwest Canada) at a very shallow angle, creating much of the mountainous terrain in the area (particularly the southern
Rocky Mountains).
Tectonic movement
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The tectonic plates of the world were mapped in the second half of the 20th century.
Tectonic movement
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Plate motion based on Global Positioning System (GPS) satellite data from NASA JPL. The vectors show direction and magnitude of motion.
Tectonic movement
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Alfred Wegener in Greenland in the winter of 1912-13.
21.
Geologic timescale
–
The table of geologic time spans, presented here, agrees with the nomenclature, dates and standard color codes set forth by the International Commission on Stratigraphy. Evidence from radiometric dating indicates that Earth is about 4.54 billion years old, the geology or deep time of Earth’s past has been organized into various units according to events which took place in each period. Older time spans, which predate the reliable record, are defined by their absolute age. Some other planets and moons within the Solar System have sufficiently rigid structures to have preserved records of their own histories, for example, Venus, Mars, dominantly fluid planets, such as the gas giants, do not preserve their history in a comparable manner. Apart from the Late Heavy Bombardment, events on other planets probably had little influence on the Earth. Construction of a scale that links the planets is, therefore, of only limited relevance to the Earths time scale. The existence, timing, and terrestrial effects of the Late Heavy Bombardment is still debated, the largest defined unit of time is the supereon, composed of eons. Eons are divided into eras, which are in turn divided into periods, epochs, the terms eonothem, erathem, system, series, and stage are used to refer to the layers of rock that correspond to these periods of geologic time in Earths history. Geologists qualify these units as early, mid, and late when referring to time, and lower, middle, for example, the lower Jurassic Series in chronostratigraphy corresponds to the early Jurassic Epoch in geochronology. The adjectives are capitalized when the subdivision is formally recognized, and lower case when not, thus early Miocene but Early Jurassic. Geologic units from the time but different parts of the world often look different and contain different fossils. For example, in North America the Lower Cambrian is called the Waucoban series that is subdivided into zones based on succession of trilobites. In East Asia and Siberia, the unit is split into Alexian, Atdabanian. A key aspect of the work of the International Commission on Stratigraphy is to reconcile this conflicting terminology, the term Anthropocene is used informally by popular culture and a growing number of scientists to describe the current epoch in which we are living. The term was coined by Paul Crutzen and Eugene Stoermer in 2000 to describe the current time, others say that humans have not even started to leave their biggest impact on Earth, and therefore the Anthropocene hasnt even started yet. Whatever the case, the ICS has not officially approved the term, leonardo da Vinci concurred with Aristotles interpretation that fossils represented the remains of ancient life. The 11th-century Persian geologist Avicenna and the 13th-century Dominican bishop Albertus Magnus extended Aristotles explanation into a theory of a petrifying fluid. Avicenna also first proposed one of the principles underlying geologic time scales, the Chinese naturalist Shen Kuo also recognized the concept of deep time
Geologic timescale
–
Key concepts
Geologic timescale
22.
Neogene
–
The Neogene is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period 23.03 million years ago to the beginning of the present Quaternary Period 2.58 Mya. The Neogene is sub-divided into two epochs, the earlier Miocene and the later Pliocene, some geologists assert that the Neogene cannot be clearly delineated from the modern geological period, the Quaternary. During this period, mammals and birds continued to evolve into modern forms. Early hominids, the ancestors of humans, appeared in Africa near the end of the period, some continental movement took place, the most significant event being the connection of North and South America at the Isthmus of Panama, late in the Pliocene. This cut off the ocean currents from the Pacific to the Atlantic ocean. The global climate cooled considerably over the course of the Neogene, the terms Neogene System and upper Tertiary System describe the rocks deposited during the Neogene Period. The continents in the Neogene were very close to their current positions, the Isthmus of Panama formed, connecting North and South America. The Indian subcontinent continued to collide with Asia, forming the Himalayas, sea levels fell, creating land bridges between Africa and Eurasia and between Eurasia and North America. The global climate became seasonal and continued an overall drying and cooling trend which began at the start of the Paleogene. The ice caps on both poles began to grow and thicken, and by the end of the period the first of a series of glaciations of the current Ice Age began, marine and continental flora and fauna have a modern appearance. The reptile group Choristodera became extinct in the part of the period. Mammals and birds continued to be the dominant terrestrial vertebrates, the first hominids, the ancestors of humans, appeared in Africa and spread into Eurasia. In response to the cooler, seasonal climate, tropical plant species gave way to deciduous ones, grasses therefore greatly diversified, and herbivorous mammals evolved alongside it, creating the many grazing animals of today such as horses, antelope, and bison. The Neogene traditionally ended at the end of the Pliocene Epoch, just before the definition of the beginning of the Quaternary Period. However, there was a movement amongst geologists to also include ongoing geological time in the Neogene, by dividing the Cenozoic Era into three periods instead of seven epochs, the periods are more closely comparable to the duration of periods in the Mesozoic and Paleozoic eras. The International Commission on Stratigraphy once proposed that the Quaternary be considered a sub-era of the Neogene, with a date of 2.58 Ma. In the 2004 proposal of the ICS, the Neogene would have consisted of the Miocene and Pliocene epochs, thus the Neogene Period ends bounding the succeeding Quaternary Period at 2.58 Mya. Digital Atlas of Neogene Life for the Southeastern United States — by San Jose State University via Web Archive
Neogene
–
Scene featuring Miocene (Early Neogene) fauna
23.
Holocene
–
The Holocene is the geological epoch that began after the Pleistocene at approximately 11,700 years before present. The term Recent has often used as an exact synonym of Holocene. The Holocene is part of the Quaternary period and its name comes from the Ancient Greek words ὅλος and καινός, meaning entirely recent. It has been identified with the current warm period, known as MIS1, given these, a new term, Anthropocene, is specifically proposed and used informally only for the very latest part of modern history involving significant human impact. It is accepted by the International Commission on Stratigraphy that the Holocene started approximately 11,700 years ago, the epoch follows the Pleistocene and the last glacial period. The Holocene can be subdivided into five time intervals, or chronozones, based on climatic fluctuations, Preboreal, Boreal, Atlantic, Subboreal and they find a general correspondence across Eurasia and North America, though the method was once thought to be of no interest. The scheme was defined for Northern Europe, but the changes were claimed to occur more widely. The periods of the include a few of the final pre-Holocene oscillations of the last glacial period. Paleontologists have not defined any faunal stages for the Holocene, if subdivision is necessary, periods of human technological development, such as the Mesolithic, Neolithic, and Bronze Age, are usually used. However, the time periods referenced by these terms vary with the emergence of those technologies in different parts of the world, climatically, the Holocene may be divided evenly into the Hypsithermal and Neoglacial periods, the boundary coincides with the start of the Bronze Age in Europe. According to some scholars, a division, the Anthropocene, has now begun. Continental motions due to plate tectonics are less than a kilometre over a span of only 10,000 years, however, ice melt caused world sea levels to rise about 35 m in the early part of the Holocene. The sea level rise and temporary land depression allowed temporary marine incursions into areas that are now far from the sea, Holocene marine fossils are known, for example, from Vermont and Michigan. Other than higher-latitude temporary marine incursions associated with depression, Holocene fossils are found primarily in lakebed, floodplain. Holocene marine deposits along low-latitude coastlines are rare because the rise in sea levels during the period exceeds any likely tectonic uplift of non-glacial origin, post-glacial rebound in the Scandinavia region resulted in the formation of the Baltic Sea. The region continues to rise, still causing weak earthquakes across Northern Europe, the equivalent event in North America was the rebound of Hudson Bay, as it shrank from its larger, immediate post-glacial Tyrrell Sea phase, to near its present boundaries. Climate has been stable over the Holocene. It appears that this was influenced by the glacial ice remaining in the Northern Hemisphere until the later date
Holocene
–
Holocene cinder cone volcano on State Highway 18 near
Veyo, Utah
Holocene
–
Bronze bead necklace,
Muséum de Toulouse
24.
Orogeny
–
An Orogeny is an event that leads to a large structural deformation of the Earths lithosphere due to the interaction between tectonic plates. Orogens or orogenic belts develop when a plate is crumpled and is pushed upwards to form mountain ranges. Orogeny is the mechanism by which mountains are built on continents. The word orogeny comes from Ancient Greek, though it was used before him, the term was employed by the American geologist G. K. Gilbert in 1890 to describe the process of mountain building as distinguished from epeirogeny. Formation of an orogen is accomplished in part by the processes of subduction or convergence of two or more continents. Orogeny usually produces long arcuate structures, known as orogenic belts, generally, orogenic belts consist of long parallel strips of rock exhibiting similar characteristics along the length of the belt. Orogenic belts are associated with zones, which consume crust, produce volcanoes. Geologists attribute the arcuate structure to the rigidity of the descending plate and these island arcs may be added to a continent during an orogenic event. The processes of orogeny can take tens of millions of years, frequently, rock formations that undergo orogeny are severely deformed and undergo metamorphism. Orogenic processes may push deeply buried rocks to the surface, sea-bottom and near-shore material may cover some or all of the orogenic area. If the orogeny is due to two continents colliding, very high mountains can result, an orogenic event may be studied, as a tectonic structural event, as a geographical event, and as a chronological event. The foreland basin forms ahead of the orogen due mainly to loading and resulting flexure of the lithosphere by the mountain belt. The basin migrates with the front and early deposited foreland basin sediments become progressively involved in folding and thrusting. Sediments deposited in the basin are mainly derived from the erosion of the actively uplifting rocks of the mountain range. The fill of many such shows an change in time from deepwater marine through shallow water to continental sediments. Although orogeny involves plate tectonics, the tectonic forces result in a variety of associated phenomena, including magmatism, metamorphism, crustal melting, what exactly happens in a specific orogen depends upon the strength and rheology of the continental lithosphere, and how these properties change during orogenesis. In addition to orogeny, the orogen is subject to other processes, for example, the Caledonian Orogeny refers to the Silurian and Devonian events that resulted from the collision of Laurentia with Eastern Avalonia and other former fragments of Gondwana. The Caledonian Orogen resulted from events and various others that are part of its peculiar orogenic cycle
Orogeny
–
Shield
Orogeny
–
Two processes that can contribute to an orogen. Top:
delamination by intrusion of hot
asthenosphere; Bottom:
Subduction of ocean crust. The two processes lead to differently located granites (bubbles in diagram), providing evidence as to which process actually occurred.
Orogeny
–
An example of
thin-skinned deformation (
thrust faulting) of the
Sevier Orogeny in
Montana. Note the white
Madison Limestone repeated, with one example in the foreground (that pinches out with distance) and another to the upper right corner and top of the picture.
Orogeny
–
Sierra Nevada Mountains (a result of delamination) as seen from the
International Space Station.
25.
Strike-slip
–
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 movement. Large faults within the Earths crust result from the action of tectonic forces. Energy release associated with movement on active faults is the cause of most earthquakes. A fault plane is the plane that represents the surface of a fault. A fault trace or fault line is the intersection of a plane with the ground surface. A fault trace is also the line commonly plotted on maps to represent a fault. Since faults do not usually consist of a single, clean fracture, the two sides of a non-vertical fault are known as the hanging wall and footwall. By definition, the wall occurs above the fault plane. This terminology comes from mining, when working a tabular ore body, because of friction and the rigidity of rocks, they cannot glide or flow past each other easily, and occasionally all movement stops. A fault in ductile rocks can also release instantaneously when the rate is too great. The energy released by instantaneous strain-release causes earthquakes, a common phenomenon along transform boundaries, slip is defined as the relative movement of geological features present on either side of a fault plane, and is a displacement vector. A faults sense of slip is defined as the motion of the rock on each side of the fault with respect to the other side. In practice, it is only possible to find the slip direction of faults. Based on direction of slip, faults can be categorized as, strike-slip. Dip-slip, offset is predominantly vertical and/or perpendicular to the fault trace, oblique-slip, combining significant strike and dip slip. The fault surface is usually vertical and the footwall moves either left or right or laterally with very little vertical motion. Strike-slip faults with left-lateral motion are known as sinistral faults. Those with right-lateral motion are known as dextral faults
Strike-slip
–
Large normal fault in
Triassic to
Lower Jurassic Blue Anchor Formation sediments near
Blue Anchor,
Somerset, UK, with several smaller normal faults in its hanging wall
Strike-slip
–
A fault in the Grands Causses as seen from
Bédarieux,
France. The left side moved down relative to the right side
Strike-slip
–
Microfault showing a
piercing point (the coin's diameter is 18 mm)
Strike-slip
–
The Piqiang Fault, a northwest trending strike-slip fault in the
Taklamakan Desert south of the
Tien Shan Mountains, China (40.3°N, 77.7°E)
26.
Los Angeles
–
Los Angeles, officially the City of Los Angeles and often known by its initials L. A. is the cultural, financial, and commercial center of Southern California. With a census-estimated 2015 population of 3,971,883, it is the second-most populous city in the United States, Los Angeles is also the seat of Los Angeles County, the most populated county in the United States. The citys inhabitants are referred to as Angelenos, historically home to the Chumash and Tongva, Los Angeles was claimed by Juan Rodríguez Cabrillo for Spain in 1542 along with the rest of what would become Alta California. The city was founded on September 4,1781, by Spanish governor Felipe de Neve. It became a part of Mexico in 1821 following the Mexican War of Independence, in 1848, at the end of the Mexican–American War, Los Angeles and the rest of California were purchased as part of the Treaty of Guadalupe Hidalgo, thereby becoming part of the United States. Los Angeles was incorporated as a municipality on April 4,1850, the discovery of oil in the 1890s brought rapid growth to the city. The completion of the Los Angeles Aqueduct in 1913, delivering water from Eastern California, nicknamed the City of Angels, Los Angeles is known for its Mediterranean climate, ethnic diversity, and sprawling metropolis. Los Angeles also has an economy in culture, media, fashion, science, sports, technology, education, medicine. A global city, it has been ranked 6th in the Global Cities Index, the city is home to renowned institutions covering a broad range of professional and cultural fields, and is one of the most substantial economic engines within the United States. The Los Angeles combined statistical area has a gross metropolitan product of $831 billion, making it the third-largest in the world, after the Greater Tokyo and New York metropolitan areas. The city has hosted the Summer Olympic Games in 1932 and 1984 and is bidding to host the 2024 Summer Olympics and thus become the second city after London to have hosted the Games three times. The Los Angeles area also hosted the 1994 FIFA mens World Cup final match as well as the 1999 FIFA womens World Cup final match, the mens event was watched on television by over 700 million people worldwide. The Los Angeles coastal area was first settled by the Tongva, a Gabrielino settlement in the area was called iyáangẚ, meaning poison oak place. Gaspar de Portolà and Franciscan missionary Juan Crespí, reached the present site of Los Angeles on August 2,1769, in 1771, Franciscan friar Junípero Serra directed the building of the Mission San Gabriel Arcángel, the first mission in the area. The Queen of the Angels is an honorific of the Virgin Mary, two-thirds of the settlers were mestizo or mulatto with a mixture of African, indigenous and European ancestry. The settlement remained a small town for decades, but by 1820. Today, the pueblo is commemorated in the district of Los Angeles Pueblo Plaza and Olvera Street. New Spain achieved its independence from the Spanish Empire in 1821, during Mexican rule, Governor Pío Pico made Los Angeles Alta Californias regional capital
Los Angeles
Los Angeles
Los Angeles
Los Angeles
27.
University of California, Berkeley
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The University of California, Berkeley, is a public research university located in Berkeley, California. In 1960s, UC Berkeley was particularly noted for the Free Speech Movement as well as the Anti-Vietnam War Movement led by its students. S, Department of Energy, and is home to many world-renowned research institutes and organizations including Mathematical Sciences Research Institute and Space Sciences Laboratory. Faculty member J. R. Oppenheimer, the father of the atomic bomb, Lawrence Livermore Lab also discovered or co-discovered six chemical elements. The Academic Ranking of World Universities also ranks the University of California, Berkeley, third in the world overall, in 1866, the private College of California purchased the land comprising the current Berkeley campus. Ten faculty members and almost 40 students made up the new University of California when it opened in Oakland in 1869, billings was a trustee of the College of California and suggested that the college be named in honor of the Anglo-Irish philosopher George Berkeley. In 1870, Henry Durant, the founder of the College of California, with the completion of North and South Halls in 1873, the university relocated to its Berkeley location with 167 male and 22 female students and held its first classes. In 1905, the University Farm was established near Sacramento, ultimately becoming the University of California, by the 1920s, the number of campus buildings had grown substantially, and included twenty structures designed by architect John Galen Howard. Robert Gordon Sproul served as president from 1930 to 1958, by 1942, the American Council on Education ranked UC Berkeley second only to Harvard University in the number of distinguished departments. During World War II, following Glenn Seaborgs then-secret discovery of plutonium, UC Berkeley physics professor J. Robert Oppenheimer was named scientific head of the Manhattan Project in 1942. Along with the Lawrence Berkeley National Laboratory, Berkeley is now a partner in managing two other labs, Los Alamos National Laboratory and Lawrence Livermore National Laboratory, originally, military training was compulsory for male undergraduates, and Berkeley housed an armory for that purpose. In 1917, Berkeleys ROTC program was established, and its School of Military Aeronautics trained future pilots, including Jimmy Doolittle, both Robert McNamara and Frederick C. Weyand graduated from UC Berkeleys ROTC program, earning B. A. degrees in 1937 and 1938, in 1926, future fleet admiral Chester W. Nimitz established the first Naval Reserve Officers Training Corps unit at Berkeley. The Board of Regents ended compulsory military training at Berkeley in 1962, during the McCarthy era in 1949, the Board of Regents adopted an anti-communist loyalty oath. A number of faculty members objected and were dismissed, ten years passed before they were reinstated with back pay, in 1952, the University of California became an entity separate from the Berkeley campus. Each campus was given autonomy and its own Chancellor. Then-president Sproul assumed presidency of the entire University of California system, Berkeley gained a reputation for student activism in the 1960s with the Free Speech Movement of 1964 and opposition to the Vietnam War. In the highly publicized Peoples Park protest in 1969, students and the school conflicted over use of a plot of land, then governor of California Ronald Reagan called the Berkeley campus a haven for communist sympathizers, protesters, and sex deviants. Modern students at Berkeley are less active, with a greater percentage of moderates and conservatives
University of California, Berkeley
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View, from Memorial Glade, of Sather Tower (The Campanile), the center of UC Berkeley. The ring of its bells and clock can be heard from all over campus.
University of California, Berkeley
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Seal of the University of California, Berkeley
University of California, Berkeley
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UC Berkeley Students participate in a one-day Peace Strike opposing U.S. involvement in World War II. April 19, 1940
University of California, Berkeley
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Sather Tower (the Campanile) looking out over the San Francisco Bay and
Mount Tamalpais.
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Thomas Dibblee
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Thomas Wilson Dibblee, Jr. was an American geologist best known for his geological mapping. Dibblee was born in 1911, the eldest son of Thomas Dibblee Sr. and his earliest California ancestor was Captain José de la Guerra y Noriega, the Comandante of the Presidio of Santa Barbara. Dibblee grew up on Rancho San Julian, one of the Dibblee - de la Guerra family ranches and he became interested in geology as a boy, when he assisted a geologist who surveyed the family ranch for oil-bearing structures. His field mapping led to the discovery of the Russell Ranch Oil Field, the first oil field to be found in the Cuyama Valley, in 1948, and then to the nearby larger South Cuyama Oil Field in 1949. Dibblee was known for roughing it during his field mapping trips, when he submitted one expense account totaling $14. He joined the US Geological Survey in 1952, and was assigned to geologic mapping in the Mojave Desert, in 1953 he and co-worker Mason Hill published a paper proposing 350 miles of lateral movement along the San Andreas Fault. At that time, prior to plate tectonics theory, there was no mechanism that could cause such large-scale movements. Dibblee retired from the USGS in 1977, and the year began mapping the geology of the Los Padres National Forest as a volunteer. Although retired, he mapped the geology of more than 3,000 square miles in the national forest, in 1949 Dibblee married Loretta Escabosa, whom he met when she was a secretary at Richfield Oil. They had a marriage, with no children. Dibblee died in 2004, at age 93, in Santa Barbara, in 2002 the foundation was adopted by the Santa Barbara Museum of Natural History. The foundation continues to publish maps based on Dibblee’s work, “San Andreas, Garlock, and Big Pine faults, California, ” Geological Society of America Bulletin, April 1953, p. 443-458. This is considered a classic publication in the history of plate tectonics theory
Thomas Dibblee
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Tom Dibblee, taken in 2003
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San Andreas Fault Observatory at Depth
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The San Andreas Fault Observatory at Depth is a research project aimed at collecting geological data about the San Andreas Fault for the purpose of predicting and analyzing future earthquakes. This data, along with samples collected during drilling, could shed new light on geochemical and mechanical properties around the fault zone, Earthscope is funded by the National Science Foundation in conjunction with the USGS and NASA. Data collected at SAFOD are available from The Northern California Earthquake Data Center at U. C, berkeley and at the IRIS DMC. Chikyu Hakken, deep oceanic drilling program Earthscope Integrated Ocean Drilling Program Kola Borehole KTB Borehole Mohorovičić discontinuity Project Mohole Ellsworth, seismology in the Source, The San Andreas Fault Observatory at Depth. Ellsworth, W. S. Hickman, M. Zoback, E. Davis, L. Gee, R. Huggins, R. Krug, observing the San Andreas Fault at depth. Scientific drilling into the San Andreas fault and site characterization research, Planning, the San Andreas Fault Observatory at Depth, testing fundamental theories of earthquake mechanics. Zoback, M. Scientific Drilling into the San Andreas Fault, Zoback, M. D. S. Hickman, W. Ellsworth. Overview of SAFOD Phases 1 and 2, Drilling, sampling, Hickman, W. Ellsworth, D. Kirschner, N. B. Preliminary Results from SAFOD Phase 3, Implications for the state of stress and shear localization in, american Geophysical Union, Fall Meeting 2007, abstract# T13G-03. Injection-induced earthquakes and crustal stress at 9 km depth at the KTB deep drilling site, GFZ German Research Centre for Geosciences, Telegrafenberg, D-14473 Potsdam, Germany. ICDP – International Continental Scientific Drilling Program, German Continental Scientific Deep Drilling Program. CS1 maint, Multiple names, authors list KTB Deep Crustal Laboratory of GFZ, KTB Deep Crustal Laboratory of GFZ. San Andreas Fault Observatory at Depth, San Andreas Fault Observatory at Depth. EarthScope http, //www. earthscope. org IDCP San Andreas Fault Observatory at Depth
San Andreas Fault Observatory at Depth
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Schematic representation of the SAFOD borehole and pilot hole
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Parkfield, California
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Parkfield is an unincorporated community in Monterey County, California. It is located on Little Cholame Creek 21 miles east of Bradley, as of 2007 road signs announce the population as 18. Parkfield is located at 35°53′59″N 120°25′58″W in the Temblor Range between the San Joaquin Valley and the Central Coast, at an elevation of 1,529 feet above sea level. Mining and Homesteading used to be an activity in this community, but the mines were exhausted below economic recovery levels. Today, it is a town of about 18 people. There is a tourism industry in the town based on equine-related events, hunting, a bluegrass music festival. The Parkfield motto is, Be here when it happens, a post office operated at Parkfield from 1884 to 1954. The towns original name of Russelsville was rejected by the post office, the ZIP Code is 93451, and the community is inside area code 805. Parkfield lies along the San Andreas Fault, one of the longest and most active faults in the United States, the fault marks the divide between the North American Plate and the Pacific Plate. There is a bridge across the creek with piers on either side that have shifted more than five feet relative to one due to aseismic creep since the bridge was constructed in 1936. The bridge sports signage announcing to drivers that they are crossing the plate boundary, since at least 1857, Parkfield has experienced a magnitude 6 or greater earthquake about every 22 years. Parkfield is the most closely observed earthquake zone in the world, scientists constantly measure the strain in rocks, heat flow, microseismicity, and geomagnetism around Parkfield. Since 1985, the United States Geological Survey has been working on a known as The Parkfield Experiment. The experiments purpose is to understand the physics of earthquakes — what actually happens on the fault and in the surrounding region before, during. In 2004, work began just north of Parkfield on the San Andreas Fault Observatory at Depth, the goal of SAFOD is to drill a hole nearly 2.5 miles into the Earths crust, across the San Andreas Fault. The specific target of the probe was a patch of fault known to generate sequences of repeating microearthquakes of around magnitude 1.0. The drilling was completed in the midyear of 2005, and an array of sensors was installed to capture and it is hoped that SAFOD observations will provide insight into the source mechanisms of these small earthquakes, which can be scaled up in an effort to understand larger events. The drilling discovered a mineral called serpentinite at the site of origin of 2004 earthquake, serpentinite can transform into talc, a very soft mineral, thus facilitating easy slippage of plates
Parkfield, California
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Parkfield Cafe
