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Rarotonga Hotspot
The Rarotonga hotspot is a volcanic hotspot in the southern Pacific Ocean. The hotspot was responsible for the formation of Rarotonga and some volcanics of Aitutaki. In addition to these volcanoes in the Cook Islands, the composition of volcanic rocks in Samoa and in the Lau Basin may have been influenced by the Rarotonga hotspot, and some atolls and seamounts in the Marshall Islands may have formed on the hotspot as well. Geology Oceanic plateaus and linear volcanic chains dot the floor of the Pacific Ocean. Their formation has been explained with mantle plumes which rise from the core-mantle boundary and spread out when they rise, forming a large "head" that causes intense volcanic activity once it hits the crust. This volcanism is responsible for the formation of the oceanic plateaus. Later, the remnant "tail" of the plume is still rising and induces the formation of volcano chains as the crust moves over the plume tail, thus forming the linear chains. A number of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hotspots
Hotspot, Hot Spot or Hot spot may refer to: Places * Hot Spot, Kentucky, a community in the United States Arts, entertainment, and media Fictional entities * Hot Spot (comics), a name for the DC Comics character Isaiah Crockett * Hot Spot (Transformers), any of several characters Films * ''Hot Spot'' (1941 film), later retitled ''I Wake Up Screaming'' * ''Hot Spot'' (1945 film), a Private Snafu film * ''The Hot Spot'', a 1990 neo-noir film Other uses in arts, entertainment, and media * ''Hot Spot'' (board game), a 1979 board game published by Metagaming Concepts * "Hot Spot" (''Burn Notice''), a television episode * ''Hot Spot'' (musical), 1963 * "Hot Spot" (song), by Foxy Brown * ''Hotspot'' (album), a 2020 album by Pet Shop Boys * ''The Hot Spot'' (Podcast), a GameSpot podcast Computing * Hot spot (computer programming), a compute-intensive region of a program * Hot spot, an area which is customizable by users in software frameworks * Hotspot (Wi-Fi), a wireles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superswell
A superswell is a large area of anomalously high topography and shallow ocean regions. These areas of anomalous topography are byproducts of large upwelling of mantle material from the core–mantle boundary, referred to as superplumes. Two present day superswells have been identified: the African superswell and the South Pacific superswell. In addition to these, the Darwin Rise in the south central Pacific Ocean is thought to be a paleosuperswell, showing evidence of being uplifted compared to surrounding ancient ocean topography. Superplume Data shows a dramatic increase in crustal production from 125-120 Ma. (million years) to 70 Ma, largely in East Pacific Rise areas, although the marked increase in production rates of crustal material was also seen in the Gondwana ridges, as well as in oceanic plateaus. This period of increased crustal production is interpreted as a superplume event. This "pulse" of increased crustal production peaked soon after the initial plume (be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magma
Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural satellites. Besides molten rock, magma may also contain suspended crystals and gas bubbles. Magma is produced by melting of the mantle or the crust in various tectonic settings, which on Earth include subduction zones, continental rift zones, mid-ocean ridges and hotspots. Mantle and crustal melts migrate upwards through the crust where they are thought to be stored in magma chambers or trans-crustal crystal-rich mush zones. During magma's storage in the crust, its composition may be modified by fractional crystallization, contamination with crustal melts, magma mixing, and degassing. Following its ascent through the crust, magma may feed a volcano and be extruded as lava, or it may solidify underground to form an intrusion, such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Back-arc
A back-arc basin is a type of geologic basin, found at some convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found in the western Pacific Ocean. Most of them result from tensional forces, caused by a process known as oceanic trench rollback, where a subduction zone moves towards the subducting plate. Back-arc basins were initially an unexpected phenomenon in plate tectonics, as convergent boundaries were expected to universally be zones of compression. However, in 1970, Dan Karig published a model of back-arc basins consistent with plate tectonics. Structural characteristics Back-arc basins are typically very long and relatively narrow, often thousands of kilometers long while only being a few hundred kilometers wide at most. For back-arc extension to form, a subduction zone is required, but not all subduction zones have a back-arc extension feature. Back-arc basins are found in ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subducted
Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the heavier plate dives beneath the second plate and sinks into the mantle. A region where this process occurs is known as a subduction zone, and its surface expression is known as an arc-trench complex. The process of subduction has created most of the Earth's continental crust. Rates of subduction are typically measured in centimeters per year, with the average rate of convergence being approximately two to eight centimeters per year along most plate boundaries. Subduction is possible because the cold oceanic lithosphere is slightly denser than the underlying asthenosphere, the hot, ductile layer in the upper mantle underlying the cold, rigid lithosphere. Once initiated, stable subduction is driven mostly by the negative buoyancy of the de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rejuvenated Stage Volcanism
The fifteen volcanoes that make up the eight principal islands of Hawaii are the youngest in a chain of more than 129 volcanoes that stretch across the North Pacific Ocean, called the Hawaiian–Emperor seamount chain. Hawaii's volcanoes rise an average of to reach sea level from their base. The largest, Mauna Loa, is high. As shield volcanoes, they are built by accumulated lava flows, growing a few meters or feet at a time to form a broad and gently sloping shape. Hawaiian islands undergo a systematic pattern of submarine and subaerial growth that is followed by erosion. An island's stage of development reflects its distance from the Hawaii hotspot. Background The Hawaiian–Emperor seamount chain is remarkable for its length and its number of volcanoes. The chain is split into two subsections across a break, separating the older Emperor Seamount Chain from the younger Hawaiian Ridge; the V-shaped bend of the chain is easily noticeable on maps. The volcanoes are progressivel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rose Atoll
Rose Atoll, sometimes called Rose Island or Motu O Manu ("Bird Island") by people of the nearby Manu'a Islands, is an oceanic atoll within the U.S. territory of American Samoa. An uninhabited wildlife refuge, it is the southernmost point belonging to the United States. The land area is just at high tide. The total area of the atoll, including lagoon and reef flat amounts to . Just west of the northernmost point is a channel into the lagoon, about 40 m wide. There are two islets on the northeastern rim of the reef, larger Rose Island in the east (3.5 m high) and the non-vegetated Sand Island in the north (1.5 m high). The Rose Atoll Marine National Monument that lies on the two outstanding islands of the Atoll is managed cooperatively between the U.S. Fish and Wildlife Service and the government of American Samoa. History The earliest Western sighting was June 13, 1722, during the voyage of Jacob Roggeveen, who called it ''Vuil Eiland'' "useless island." The name Rose Islan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Large Low Shear-wave Velocity Province
Large means of great size. Large may also refer to: Mathematics * Arbitrarily large, a phrase in mathematics * Large cardinal, a property of certain transfinite numbers * Large category, a category with a proper class of objects and morphisms (or both) * Large diffeomorphism, a diffeomorphism that cannot be continuously connected to the identity diffeomorphism in mathematics and physics * Large numbers, numbers significantly larger than those ordinarily used in everyday life * Large ordinal, a type of number in set theory * Large sieve, a method of analytic number theory ** Larger sieve, a heightening of the large sieve * Law of large numbers, a result in probability theory * Sufficiently large, a phrase in mathematics Other uses * ''Large'' (film), a 2001 comedy film * Large (surname), an English surname * LARGE, an enzyme * Large, a British English name for the maxima (music), a note length in mensural notation * Large, or G's, or grand, slang for $1,000 US dollars * Larg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seismic Tomography
Seismic tomography or seismotomography is a technique for imaging the subsurface of the Earth with seismic waves produced by earthquakes or explosions. P-, S-, and surface waves can be used for tomographic models of different resolutions based on seismic wavelength, wave source distance, and the seismograph array coverage. The data received at seismometers are used to solve an inverse problem, wherein the locations of reflection and refraction of the wave paths are determined. This solution can be used to create 3D images of velocity anomalies which may be interpreted as structural, thermal, or compositional variations. Geoscientists use these images to better understand core, mantle, and plate tectonic processes. Theory Tomography is solved as an inverse problem. Seismic travel time data are compared to an initial Earth model and the model is modified until the best possible fit between the model predictions and observed data is found. Seismic waves would travel in straight lin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Austral Islands
The Austral Islands (french: Îles Australes, officially ''Archipel des Australes;'' ty, Tuha'a Pae) are the southernmost group of islands in French Polynesia, an overseas country of the French Republic in the South Pacific. Geographically, they consist of two separate archipelagos, namely in the northwest the Tupua'i islands (french: Îles Tubuaï) consisting of the Îles Maria, Rimatara, Rūrutu, Tupua'i Island proper and Ra'ivāvae, and in the southeast the Bass Islands (french: Îles basses) composed of the main island of Rapa Iti and the small Marotiri (also known as Bass Rocks or Îlots de Bass). Inhabitants of the islands are known for their pandanus fiber weaving skills. The islands of Maria and Marotiri are not suitable for sustained habitation. Several of the islands have uninhabited islets or rocks off their coastlines. Austral Islands' population is 6,965 on almost . The capital of the Austral Islands administrative subdivision is Tupua'i. History Whaling ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
