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Tonga–Kermadec Ridge
The Tonga–Kermadec Ridge is an oceanic ridge in the south-west Pacific Ocean underlying the Tonga–Kermadec island arc. It is a result of the most linear, fastest converging, and seismically active subduction boundary on Earth, the Kermadec–Tonga subduction zone, and consequently has the highest density of submarine volcanoes. The Tonga–Kermadec Ridge stretches more than north-northeast from New Zealand's North Island. The Pacific Plate subducts westward beneath the Australian Plate along the ridge. It is divided into two segments, the northern Tonga Ridge and southern Kermadec Ridge, by the Louisville Seamount Chain. On its western side, the ridge is flanked by two back-arc basins, the Lau Basin and Havre Trough, that began opening at 6 and 2 Ma respectively. Beyound the basins is the Lau-Colville Ridge. Together with these seafloor structures the ridge forms the eastward-migrating, 100 million year old Lau–Tonga–Havre–Kermadec arc/back-arc sys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tonga Trench
The Tonga Trench is an oceanic trench located in the southwestern Pacific Ocean. It is the deepest trench in the Southern hemisphere and the second deepest on Earth after the Mariana Trench. The fastest plate-tectonic velocity on Earth is occurring at this location, as the Pacific plate is being Subduction, subducted westward in the trench. Horizon Deep The deepest point of the Tonga Trench, the Horizon Deep at , is deep, making it the deepest point in the Southern Hemisphere and the second deepest on Earth after the Challenger Deep in the Mariana Trench. It is named for the research vessel RV Horizon, ''Horizon'' of the Scripps Institution of Oceanography, the crew of which found the deep in December 1952. As one of the deepest Hadal zone, hadal trenches, the sediment of the Horizon Deep harbours a community of Nematode, roundworms. A 2016 study found that the abundance of individuals in this community is six times greater than it is at a site on the trench edge at approximate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tafahi
Tafahi is a small () island in the north of the Tonga archipelago, in fact closer to Savaii (Samoa) than to the main islands of Tonga. It is only north-northeast away from Niuatoputapu, and fishermen commute in small outboard motorboats almost daily between the two. The island has a population of 14 (in 2021). Other names for Tafahi are Cocos Eylant (coconut island) or Boscawen island. Geography Tafahi is a volcanic island and has the typical cone shape of a stratovolcano. The mountain is called Piu-o-Tafahi (fanpalm of Tafahi) and is high. (The island, , is smaller than Niuatoputapu, but higher). The soil is extremely suited for growing kava and vanilla, whose exports to the rest of Tonga and beyond is the main occupation of the population. The harbour (merely an opening in the fringing reef, only passable by small boats) is at the northwest of the island. A steep staircase leads up to the village, with about 69 residents at the census of 2001, located on a plateau on the no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mantle Plume
A mantle plume is a proposed mechanism of convection within the Earth's mantle, hypothesized to explain anomalous volcanism. Because the plume head partially melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hotspots, such as Hawaii or Iceland, and large igneous provinces such as the Deccan and Siberian Traps. Some such volcanic regions lie far from tectonic plate boundaries, while others represent unusually large-volume volcanism near plate boundaries. Concepts Mantle plumes were first proposed by J. Tuzo Wilson in 1963 and further developed by W. Jason Morgan in 1971 and 1972. A mantle plume is posited to exist where super-heated material forms ( nucleates) at the core-mantle boundary and rises through the Earth's mantle. Rather than a continuous stream, plumes should be viewed as a series of hot bubbles of material. Reaching the brittle upper Earth's crust they form diapirs. These diapirs are "hotspots" in the crust. In particular, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Louisville Hotspot
The Louisville hotspot is a volcanic hotspot responsible for the volcanic activity that has formed the Louisville Ridge in the southern Pacific Ocean. Location The Louisville hotspot is believed to lie close to the Pacific-Antarctic Ridge, although its exact present location is uncertain. Geological history The Louisville hotspot has produced the Louisville Ridge, which is one of the longest seamount chains on Earth, stretching some from the Pacific-Antarctic Ridge to the Tonga Trench where it subducts under the Indo-Australian Plate as part of the Pacific Plate. The Louisville hotspot is believed to have been active since at least 78.8 ± 1.3 Ma based on age of the oldest seamount (Osbourn). This duration is comparable to that of the Hawaiian-Emperor seamount chain, although the rate of volcanism at the two chains are relatively different by 50% with volcanic activity at each seamount location being shorter in the Louisville seamounts at about 4 million years compared to m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Samoa Hotspot
The Samoa hotspot is a volcanic hotspot located in the south Pacific Ocean. The hotspot model describes a hot upwelling plume of magma through the Earth's crust as an explanation of how volcanic islands are formed. The hotspot idea came from J. Tuzo Wilson in 1963 based on the Hawaiian Islands volcanic chain. In theory, the Samoa hotspot is based on the Pacific Tectonic Plate travelling over a fixed hotspot located deep underneath the Samoan Islands. The Samoa hotspot includes the Samoan Islands (American Samoa and Samoa), and extends to the islands of Uvea or Wallis Island (Wallis and Futuna) and Niulakita (Tuvalu), as well as the submerged Pasco banks and Alexa Bank. As the Pacific Plate moves slowly over the hotspot, thermal activity builds up and is released in magma plume spewing through the Earth's crust, forming each island in a chain. The Samoa islands generally lie in a straight line, east to west, in the same direction of the tectonic plate 'drifting' over the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kermadec Plate
The Kermadec plate is a long and narrow tectonic plate located west of the Kermadec Trench in the south Pacific Ocean. Also included on this tectonic plate is a small portion of the North Island of New Zealand and the Kermadec Islands. It is separated from the Australian plate by a long divergent boundary which forms a back-arc basin. This area is highly prone to earthquakes and tsunamis A tsunami ( ; from , ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and underwater explosions (including detonations, la .... The Pacific plate east to west convergence rates with the Australian and Kermadec plates are among the fastest on Earth, being per year in the north and per year in the south. See also * Tonga-Kermadec Ridge References * Tectonic plates Geology of New Zealand Geography of the New Zealand seabed Geology of the Pacific Ocean Geology ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tonga Plate
The Tonga plate is a small southwest Pacific tectonic plate or microplate. It is centered at approximately 19° S. latitude and 173° E. longitude. The plate is an elongated plate oriented NNE–SSW and is a northward continuation of the Kermadec linear zone north of New Zealand. The plate is bounded on the east and north by the Pacific plate, on the northwest by the Niuafo’ou microplate, on the west and south by the Indo-Australian plate. The Tonga plate is subducting the Pacific plate along the Tonga Trench. This subduction turns into a transform fault A transform fault or transform boundary, is a fault (geology), fault along a plate boundary where the motion (physics), motion is predominantly Horizontal plane, horizontal. It ends abruptly where it connects to another plate boundary, either an ... boundary north of Tonga. An active rift or spreading center separates the Tonga plate from the Australian plate and the Niuafo’ou microplate to the west. The Tonga plate is se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Niuafo'ou Plate
The Niuafoou plate is a small tectonic plate located west of the islands of Tonga in the region of the Lau Basin. This plate is sandwiched between the Pacific plate to the north, the very unstable Tonga plate to the east and the Australian plate The Australian plate is or was a major tectonic plate in the eastern and, largely, southern hemispheres. Originally a part of the ancient continent of Gondwana, Australia remained connected to India and Antarctica until approximately when Indi ... to the west. It is primarily surrounded by divergent boundaries. This plate is riddled with active faults thus making the area extremely earthquake prone. See also * References * Tectonic plates Geology of the Pacific Ocean {{plate-tectonics-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Havre Trough
The Havre Trough (Havre Basin) is a currently actively rifting back-arc basin about to wide, between the Australian Plate and Kermadec microplate. The trough extends northward from New Zealand's offshore Taupō Volcanic Zone commencing at Zealandia's continental shelf margin and continuing as a tectonic feature, as the Lau Basin which currently contains active seafloor spreading centers. Its eastern margin is defined by the Kermadec Ridge created by Pacific Plate subduction under the Kermadec microplate, while the western margin is the remnant Lau-Colville Ridge. Geology The Havre Trough is characterised by a number of basins up to deep in the south, with several more shallow volcanic edifices that may rise to within of the ocean surface. It is a back-arc domain where rifting is universally oblique to the bounding ridges and consists of rifted horsts and grabens, extrusive magmatism and partially sedimented rifts. The western basins have flat floors and sediment in fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lau Basin
The Lau Basin is a back-arc basin (also addressed as "interarc basin") at the Australian-Pacific plate boundary. It is formed by the Pacific plate subducting under the Australian plate. The Tonga-Kermadec Ridge, a frontal arc, and the Lau-Colville Ridge, a Back-arc region, remnant arc, sit to the eastern and western sides of the basin, respectively.Gill, J. B. 1976. "Composition and Age of Lau Basin and Ridge Volcanic Rocks: Implications for Evolution of an Interarc Basin and Remnant Arc." Bulletin of the Geological Society of America 87 (10): 1384–1395. The basin has a raised transition area to the south where it joins the Havre Trough. History Lau Basin is a young basin (much is less than 5 million years old) that separates a previously continuous island arc by Extensional tectonics, extensional rifting and spreading. During the Pliocene, the Pacific plate was subducting beneath the Australian plate. The slab of the Pacific plate melted as it was thrust down, and then rose to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
