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Easter Fracture Zone
The Easter Fracture Zone is an oceanic fracture zone associated with the transform fault extending from the Tuamotu archipelago in the west to the Peru–Chile Trench to the east. The Easter Fracture Zone extends roughly 5900 kilometers from 20°S,131°W to 26°S,78°W. The landscape consists of several ridges and isolated volcanos with maximal peak elevation above the seafloor of 3000m. Because the local seafloor has depths around 4000m to the north of the fracture zone and 3400m to the south of the fracture zone, most of its volcanic peaks form seamounts. They do rise above sea level at the Pitcairn Islands and Easter Island. See also * Easter Hotspot References Easter Fracture Zone– Encyclopædia Britannica Online An encyclopedia (American English) or encyclopædia (British English) is a reference work or compendium providing summaries of knowledge either general or special to a particular field or discipline. Encyclopedias are divided into article ... Map p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fracture Zone
A fracture zone is a linear feature on the ocean floor—often hundreds, even thousands of kilometers long—resulting from the action of offset mid-ocean ridge axis segments. They are a consequence of plate tectonics. Lithospheric plates on either side of an active transform fault move in opposite directions; here, strike-slip activity occurs. Fracture zones extend past the transform faults, away from the ridge axis; seismically inactive (because both plate segments are moving in the same direction), they display evidence of past transform fault activity, primarily in the different ages of the crust on opposite sides of the zone. In actual usage, many transform faults aligned with fracture zones are often loosely referred to as "fracture zones" although technically, they are not. Structure and formation Mid-ocean ridges are divergent plate boundaries. As the plates on either side of an offset mid-ocean ridge move, a transform fault forms at the offset between the two ridges ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transform Fault
A transform fault or transform boundary, is a fault along a plate boundary where the motion is predominantly horizontal. It ends abruptly where it connects to another plate boundary, either another transform, a spreading ridge, or a subduction zone. A transform fault is a special case of a ''strike-slip fault'' that also forms a plate boundary. Most such faults are found in oceanic crust, where they accommodate the lateral offset between segments of divergent boundaries, forming a zigzag pattern. This is a result of oblique seafloor spreading where the direction of motion is not perpendicular to the trend of the overall divergent boundary. A smaller number of such faults are found on land, although these are generally better-known, such as the San Andreas Fault and North Anatolian Fault. Nomenclature Transform boundaries are also known as conservative plate boundaries because they involve no addition or loss of lithosphere at the Earth's surface. Background Geophysicist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuamotu Archipelago
The Tuamotu Archipelago or the Tuamotu Islands (french: Îles Tuamotu, officially ) are a French Polynesian chain of just under 80 islands and atolls in the southern Pacific Ocean. They constitute the largest chain of atolls in the world, extending (from northwest to southeast) over an area roughly the size of Western Europe. Their combined land area is . This archipelago's major islands are Anaa, Fakarava, Hao and Makemo. The Tuamotus have approximately 16,000 inhabitants. The islands were initially settled by Polynesians, and modern Tuamotuans have inherited from them a shared culture and the Tuamotuan language. The Tuamotus are a French overseas collectivity. History The early history of the Tuamotu islands is generally unknown. Archaeological findings suggest that the western Tuamotus were settled from the Society Islands as early as 900 CE or as late as 1200 CE. DNA evidence suggests that they were settled about 1110 CE. On the islands of Rangiroa, Manihi and Mataiva, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peru–Chile Trench
The Peru–Chile Trench, also known as the Atacama Trench, is an oceanic trench in the eastern Pacific Ocean, about off the coast of Peru and Chile. It reaches a maximum depth of below sea level in Richards Deep () and is approximately long; its mean width is and it covers an expanse of some . The trench delineates the boundary between the subducting Nazca Plate and the overriding South American Plate. Geology The trench is a result of a convergent plate boundary, where the eastern edge of the oceanic Nazca Plate is being subducted beneath the continental South American Plate. The trench is also a part of the Chile Triple Junction, an unusual junction that consists of a mid-oceanic ridge and the Chile Rise being subducted under the South American plate at the Peru-Chile Trench. Two seamount ridges within the Nazca Plate enter the subduction zone along this trench: the Nazca Ridge and the Juan Fernández Ridge. From the Chile Triple Junction to Juan Fernández Ri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcano
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are diverging or converging, and most are found underwater. For example, a mid-ocean ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from the core–mantle boundary, deep in the Earth. This results in hotspot volcanism, of which the Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seamount
A seamount is a large geologic landform that rises from the ocean floor that does not reach to the water's surface (sea level), and thus is not an island, islet or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly and are usually found rising from the seafloor to in height. They are defined by oceanographers as independent features that rise to at least above the seafloor, characteristically of conical form.IHO, 2008. Standardization of Undersea Feature Names: Guidelines Proposal form Terminology, 4th ed. International Hydrographic Organization and Intergovernmental Oceanographic Commission, Monaco. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea. During their evolution over geologic time, the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface. After they have subsided and sunk below the sea surface such flat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pitcairn Islands
The Pitcairn Islands (; Pitkern: '), officially the Pitcairn, Henderson, Ducie and Oeno Islands, is a group of four volcanic islands in the southern Pacific Ocean that form the sole British Overseas Territory in the Pacific Ocean. The four islands—Pitcairn, Henderson, Ducie and Oeno—are scattered across several hundred miles of ocean and have a combined land area of about . Henderson Island accounts for 86% of the land area, but only Pitcairn Island is inhabited. The islands nearest to the Pitcairn Islands are Mangareva (of French Polynesia) at 688 km to the west and Easter Island at 1,929 km to the east. The Pitcairn Islanders are a biracial ethnic group descended mostly from nine ''Bounty'' mutineers and a handful of Tahitian consorts—as is still apparent from the surnames of many of the islanders. The mutiny and its aftermath have been the subject of many books and films. As of January 2020, the territory had only 47 permanent inhabitants. History Polynesi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Easter Island
Easter Island ( rap, Rapa Nui; es, Isla de Pascua) is an island and special territory of Chile in the southeastern Pacific Ocean, at the southeasternmost point of the Polynesian Triangle in Oceania. The island is most famous for its nearly 1,000 extant monumental statues, called ''moai'', which were created by the early Rapa Nui people. In 1995, UNESCO named Easter Island a World Heritage Site, with much of the island protected within Rapa Nui National Park. Experts disagree on when the island's Polynesian inhabitants first reached the island. While many in the research community cited evidence that they arrived around the year 800, there is compelling evidence presented in a 2007 study that places their arrival closer to 1200. The inhabitants created a thriving and industrious culture, as evidenced by the island's numerous enormous stone ''moai'' and other artifacts. However, land clearing for cultivation and the introduction of the Polynesian rat led to gradual deforest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Easter Hotspot
The Easter hotspot is a volcanic hotspot located in the southeastern Pacific Ocean. The hotspot created the Sala y Gómez Ridge which includes Easter Island, Salas y Gómez Island and the Pukao Seamount which is at the ridge's young western edge. Easter Island, because of its tectonomagmatic features (low eruptive rate, scattered rift zones, and scarce lateral collapses), represents an end-member type of hotspot volcano in this chain. The hotspot may also be responsible for the formation of the Tuamotu Archipelago, Line Islands, and the chain of seamounts lying in between. See also * Easter Island § Geology * Moai (seamount) The Moai Seamount is a submarine volcano, the second most westerly in the Easter Seamount Chain or Sala y Gómez ridge. It is east of Pukao seamount and west of Easter Island. It rises over 2,500 metres from the ocean floor to within a few hun ... References External links * Volcanism of Chile Hotspots of the Pacific Ocean Geograp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encyclopædia Britannica Online
An encyclopedia (American English) or encyclopædia (British English) is a reference work or compendium providing summaries of knowledge either general or special to a particular field or discipline. Encyclopedias are divided into articles or entries that are arranged alphabetically by article name or by thematic categories, or else are hyperlinked and searchable. Encyclopedia entries are longer and more detailed than those in most dictionaries. Generally speaking, encyclopedia articles focus on '' factual information'' concerning the subject named in the article's title; this is unlike dictionary entries, which focus on linguistic information about words, such as their etymology, meaning, pronunciation, use, and grammatical forms.Béjoint, Henri (2000)''Modern Lexicography'', pp. 30–31. Oxford University Press. Encyclopedias have existed for around 2,000 years and have evolved considerably during that time as regards language (written in a major international or a v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fracture Zones
Fracture is the separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the solid. If a displacement develops perpendicular to the surface, it is called a normal tensile crack or simply a crack; if a displacement develops tangentially, it is called a shear crack, slip band or dislocation. Brittle fractures occur with no apparent deformation before fracture. Ductile fractures occur after visible deformation. Fracture strength, or breaking strength, is the stress when a specimen fails or fractures. The detailed understanding of how a fracture occurs and develops in materials is the object of fracture mechanics. Strength Fracture strength, also known as breaking strength, is the stress at which a specimen fails via fracture. This is usually determined for a given specimen by a tensile test, which charts the stress–strain c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
