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Hikurangi Plateau
The Hikurangi Plateau is an oceanic plateau in the South Pacific Ocean east of the North Island of New Zealand. It is part of a large igneous province (LIP) together with Manihiki and Ontong Java, now located and north of Hikurangi respectively. Mount Hikurangi, in Māori mythology the first part of the North Island to emerge from the ocean, gave its name to the plateau. Geological setting The Hikurangi Plateau covers approximately and reaches below sea level. Hikurangi Plateau is cut by the Hikurangi Channel, a 2000 km abyssal channel that starts at Kaikoura and runs along the Hikurangi Trench as far as the Māhia Peninsula before crossing the plateau and ending in the South-west Pacific abyssal plain. Tectonic evolution Two models have been proposed for the formation of Hikurangi. It can be derived from the mantle plume that caused the break-up of Gondwana and the separation of Zealandia from Antarctica 107 Ma. Alternatively, it could have formed together ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greater Ontong Java Event
The Ontong Java Plateau (OJP) is a massive oceanic plateau located in the southwestern Pacific Ocean, north of the Solomon Islands. The OJP was formed around (Ma) with a much smaller volcanic event around 90 Ma. Two other southwestern Pacific plateaus, Manihiki and Hikurangi, now separated from the OJP by Cretaceous oceanic basins, are of similar age and composition and probably formed as a single plateau and a contiguous large igneous province together with the OJP. When eruption of lava had finished, the Ontong Java–Manihiki–Hikurangi plateau covered 1% of Earth's surface and represented a volume of of basaltic magma. This "Ontong Java event", first proposed in 1991, represents the largest volcanic event of the past 200 million years, with a magma eruption rate estimated at up to per year over 3 million years, several times larger than the Deccan Traps. The smooth surface of the OJP is punctuated by seamounts such as the Ontong Java Atoll, one of the largest atolls ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geography Of The New Zealand Seabed
Geography (from Greek: , ''geographia''. Combination of Greek words ‘Geo’ (The Earth) and ‘Graphien’ (to describe), literally "earth description") is a field of science devoted to the study of the lands, features, inhabitants, and phenomena of Earth. The first recorded use of the word γεωγραφία was as a title of a book by Greek scholar Eratosthenes (276–194 BC). Geography is an all-encompassing discipline that seeks an understanding of Earth and its human and natural complexities—not merely where objects are, but also how they have changed and come to be. While geography is specific to Earth, many concepts can be applied more broadly to other celestial bodies in the field of planetary science. One such concept, the first law of geography, proposed by Waldo Tobler, is "everything is related to everything else, but near things are more related than distant things." Geography has been called "the world discipline" and "the bridge between the human and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 the most linear, fastest converging, and most seismically active subduction boundary on Earth, 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. Together with these younger basins the ridge forms the eastward-migrating, 100 Ma-old Lau-Tonga-Havre-Kermadec arc/back-arc system or complex. The extension in the Lau-Havre basin results in a higher rate of subduction than convergence along the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Large Low-shear-velocity Provinces
Large low-shear-velocity provinces, LLSVPs, also called LLVPs or superplumes, are characteristic structures of parts of the lowermost mantle (the region surrounding the outer core) of Earth. These provinces are characterized by slow shear wave velocities and were discovered by seismic tomography of deep Earth. There are two main provinces: the African LLSVP and the Pacific LLSVP. Both extend laterally for thousands of kilometers and possibly up to vertically from the core–mantle boundary. The Pacific LLSVP is across, and underlies four hotspots that suggest multiple mantle plumes underneath. These zones represent around 8% of the volume of the mantle (6% of Earth). Other names for LLSVPs include " superswells", "thermo-chemical piles", or "hidden reservoirs". Most of these names, however, are more interpretive of their proposed geodynamical or geochemical effects. For example, the name "thermo-chemical pile" interprets LLSVPs as lower-mantle piles of thermally hot and/or che ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Campbell Plateau
The Campbell Plateau is a large oceanic plateau south of New Zealand and the Chatham Rise. It originated in the Gondwanan breakup and is part of Zealandia, a largely submerged continent. The above sea level parts of the plateau — the Bounty Islands, Antipodes Islands, Auckland Islands and Campbell Island — form part of the New Zealand Subantarctic Islands which were declared a World Heritage Site in 1998. Large parts of the Campbell Plateau lie less than 1000 m below sea level. It rises to 500 m at the Pukaki Rise and emerges above sea level at the Auckland and Campbell Islands. Covering an area of , the Campbell Plateau has a gently undulating bathymetry with major rises trending east-west: Campbell Island Rise, Pukaki Rise, and Bounty Island Ridge. There are two near-parallel rises on the western margin: Stewart Island–Snare Island Rise and Auckland Island platform. The continental slopes are steep on western and southern margins while the northern m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1931 Hawke's Bay Earthquake
Events January * January 2 – South Dakota native Ernest Lawrence invents the cyclotron, used to accelerate particles to study nuclear physics. * January 4 – German pilot Elly Beinhorn begins her flight to Africa. * January 22 – Sir Isaac Isaacs is sworn in as the first Australian-born Governor-General of Australia. * January 25 – Mohandas Gandhi is again released from imprisonment in India. * January 27 – Pierre Laval forms a government in France. February * February 4 – Soviet leader Joseph Stalin gives a speech calling for rapid industrialization, arguing that only strong industrialized countries will win wars, while "weak" nations are "beaten". Stalin states: "We are fifty or a hundred years behind the advanced countries. We must make good this distance in ten years. Either we do it, or they will crush us." The first five-year plan in the Soviet Union is intensified, for the industrialization and collectivization of agriculture. * February 10 – Official ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moment Magnitude Scale
The moment magnitude scale (MMS; denoted explicitly with or Mw, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. It was defined in a 1979 paper by Thomas C. Hanks and Hiroo Kanamori. Similar to the local magnitude/Richter scale () defined by Charles Francis Richter in 1935, it uses a logarithmic scale; small earthquakes have approximately the same magnitudes on both scales. Despite the difference, news media often says "Richter scale" when referring to the moment magnitude scale. Moment magnitude () is considered the authoritative magnitude scale for ranking earthquakes by size. It is more directly related to the energy of an earthquake than other scales, and does not saturate—that is, it does not underestimate magnitudes as other scales do in certain conditions. It has become the standard scale used by seismological authorities like the U.S. Geological SurveyThe "USGS ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forearc
Forearc is a plate tectonic term referring to a region between an oceanic trench, also known as a subduction zone, and the associated volcanic arc. Forearc regions are present along a convergent margins and eponymously form 'in front of' the volcanic arcs that are characteristic of convergent plate margins. A back-arc region is the companion region behind the volcanic arc. Many forearcs have an accretionary wedge which may form a topographic ridge known as an outer arc ridge that parallels the volcanic arc. Between the accretionary wedge and the volcanic arc a forearc basin, sometimes referred to as an outer arc trough, may be present and can accumulate thick deposits of sediment. Due to tectonic stresses as one tectonic plate rides over another, forearc regions are sources for great thrust earthquakes. Formation During subduction, an oceanic plate is thrust below another tectonic plate, which may be oceanic or continental. Water and other volatiles in the down-going pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kermadec-Tonga Subduction Zone
The Kermadec-Tonga subduction zone is a convergent plate boundary that stretches from the North Island of New Zealand northward. The formation of the Kermadec and Tonga Plates started about 4–5 million years ago. Today, the eastern boundary of the Tonga Plate is one of the fastest subduction zones, with a rate up to 24 cm/yr. The trench formed between the Kermadec-Tonga and Pacific Plates is also home to the second deepest trench in the world, at about 10,800 m, as well as the longest chain of submerged volcanoes. Geological setting The Kermadec-Tonga subduction zone is a convergent plate boundary that stretches from the southwest of the Kermadec Plate (northeast of New Zealand) to the northwest tip of the Tonga Plate, with the Pacific Plate being subducted under both the Kermadec and Tonga Plates. The Kermadec and Tonga Plates are micro oceanic plates in the Pacific Ocean, bounded by the Australian and Pacific Plates to the west and east respectively. The Kermadec Pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Southern Alps
The Southern Alps (; officially Southern Alps / Kā Tiritiri o te Moana) is a mountain range extending along much of the length of New Zealand's South Island, reaching its greatest elevations near the range's western side. The name "Southern Alps" generally refers to the entire range, although separate names are given to many of the smaller ranges that form part of it. The range includes the South Island's Main Divide, which separates the water catchments of the more heavily populated eastern side of the island from those on the west coast. Politically, the Main Divide forms the boundary between the Marlborough, Canterbury and Otago regions to the southeast and the Tasman and West Coast regions to the northwest. Names The Māori name of the range is , meaning "the Mirage of the Ocean". The English explorer James Cook bestowed the name ''Southern Alps'' on 23 March 1770, admiring their "prodigious height". p. 384. They had previously been noted by Abel Tasman in 1642, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of New Zealand
The geology of New Zealand is noted for its volcanic activity, earthquakes and geothermal areas because of its position on the boundary of the Australian Plate and Pacific Plates. New Zealand is part of Zealandia, a microcontinent nearly half the size of Australia that broke away from the Gondwanan supercontinent about 83 million years ago. New Zealand's early separation from other landmasses and subsequent evolution have created a unique fossil record and modern ecology. New Zealand's geology can be simplified into three phases. First the basement rocks of New Zealand formed. These rocks were once part of the super-continent of Gondwana, along with South America, Africa, Madagascar, India, Antarctica and Australia. The rocks that now form the, mostly submerged, continent of Zealandia were then nestled between Eastern Australia and Western Antarctica. Secondly New Zealand drifted away from Gondwana and many sedimentary basins formed, which later became the sedimentary rocks cove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
