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Macdonald Seamount
Macdonald seamount (named after Gordon A. Macdonald) is a seamount in Polynesia, southeast of the Austral Islands and in the neighbourhood of a system of seamounts that include the Ngatemato seamounts and the Taukina seamounts. It rises from the seafloor to a depth of about and has a flat top, but the height of its top appears to vary with volcanic activity. There are some subsidiary cones such as Macdocald seamount. The seamount was discovered in 1967 and has been periodically active with gas release and seismic activity since then. There is hydrothermal activity on Macdonald, and the vents are populated by hyperthermophilic bacteria. Macdonald seamount is the currently active volcano of the Macdonald hotspot, a volcanic hotspot that has formed this seamount and some other volcanoes. Eruptions occurred in 1967, 1977, 1979–1983 and 1987–1989, and earthquakes were recorded in 2007. The activity, which has produced basaltic rocks, has modified the shape of the volcano a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continents of Asia and Oceania in the west and the Americas in the east. At in area (as defined with a southern Antarctic border), this largest division of the World Ocean—and, in turn, the hydrosphere—covers about 46% of Earth's water surface and about 32% of its total surface area, larger than Earth's entire land area combined .Pacific Ocean . '' Britannica Concise.'' 2008: Encyclopædia Britannica, Inc. The centers of both the |
Hotspot (geology)
In geology, hotspots (or hot spots) are volcanic locales thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle. Examples include the Hawaii, Iceland, and Yellowstone hotspots. A hotspot's position on the Earth's surface is independent of tectonic plate boundaries, and so hotspots may create a chain of volcanoes as the plates move above them. There are two hypotheses that attempt to explain their origins. One suggests that hotspots are due to mantle plumes that rise as thermal diapirs from the core–mantle boundary. The alternative plate theory is that the mantle source beneath a hotspot is not anomalously hot, rather the crust above is unusually weak or thin, so that lithospheric extension permits the passive rising of melt from shallow depths. Origin The origins of the concept of hotspots lie in the work of J. Tuzo Wilson, who postulated in 1963 that the formation of the Hawaiian Islands resulted from the slow movement of a tecton ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
East Pacific Rise
The East Pacific Rise is a mid-ocean rise (termed an oceanic rise and not a mid-ocean ridge due to its higher rate of spreading that results in less elevation increase and more regular terrain), a divergent tectonic plate boundary located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from (north to south) the North American Plate, the Rivera Plate, the Cocos Plate, the Nazca Plate, and the Antarctic Plate. It runs south from the Gulf of California in the Salton Sea basin in Southern California to a point near 55° S, 130° W, where it joins the Pacific-Antarctic Ridge trending west-southwest towards Antarctica, near New Zealand (though in some uses the PAR is regarded as the southern section of the EPR). Much of the rise lies about 3200 km (2000 mi) off the South American coast and rises about 1,800–2,700 m (6,000–9,000 ft) above the surrounding seafloor. Overview The oceanic crust is moving away from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polynesian Languages
The Polynesian languages form a genealogical group of languages, itself part of the Oceanic branch of the Austronesian family. There are 38 Polynesian languages, representing 7 percent of the 522 Oceanic languages, and 3 percent of the Austronesian family. While half of them are spoken in geographical Polynesia (the Polynesian triangle), the other half – known as Polynesian outliers – are spoken in other parts of the Pacific: from Micronesia to atolls scattered in Papua New Guinea, the Solomon Islands or Vanuatu. The most prominent Polynesian languages, in number of speakers, are Tahitian, Samoan, Tongan, Māori and Hawaiian. The ancestors of modern Polynesians were Lapita navigators, who settled in the Tonga and Samoa areas about 3,000 years ago. Linguists and archaeologists estimate that this first population went through common development during about 1000 years, giving rise to Proto-Polynesian, the linguistic ancestor of all modern Polynesian languages. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
President Thiers Bank
President Thiers Bank is a broad guyot, which lies northwest of Rapa and southeast of Raivavae, in the Austral Islands. Its summit reaches a depth of . It may have been created by the Macdonald hotspot. Another theory sees in the seamount the endpoint of an alignment that starts with Aitutaki Aitutaki, also traditionally known as Araura and Utataki, is the second most-populated island in the Cook Islands, after Rarotonga. It is an "almost atoll", with fifteen islets in a lagoon adjacent to the main island. Total land area is , and the ... and also involves one volcanic phase at Raivavae. References Sources * Seamounts of the Pacific Ocean Undersea banks of the Pacific Ocean Guyots Geography of the Austral Islands {{Ocean-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foundation Seamounts
Foundation Seamounts are a series of seamounts in the southern Pacific Ocean. Discovered in 1992, these seamounts form a long chain which starts from the Pacific-Antarctic Ridge. Some of these seamounts may have once emerged from the ocean. The Foundation Seamounts were probably formed by a now-weakening mantle plume called the Foundation hotspot that is located close to the Pacific-Antarctic Ridge. It is possible that this hotspot generated additional volcanoes, such as the Ngatemato and Taukina seamounts farther west. The oldest volcanism on the Foundation Seamounts occurred 21 million years ago, while the youngest volcanism appears to be hydrothermal venting and the eruption of a lava flow between 1997 and 2001 where the Foundation Seamounts intersect the Pacific-Antarctic Ridge. Name and discovery The Foundation Seamounts were discovered in 1992 through satellite altimetry observations. They are named after the National Science Foundation, a name-giving inspired to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rapa Iti
Rapa, also called Rapa Iti, or "Little Rapa", to distinguish it from Easter Island, whose Polynesian name is Rapa Nui, is the largest and only inhabited island of the Bass Islands in French Polynesia. An older name for the island is Oparo. The total land area including offshore islets is . As of the 2017 census, Rapa had a population of 507.Répartition de la population en Polynésie française en 2017 Institut de la statistique de la Polynésie française The island's highest point is at elevation at Mont Perahu. Its main town is Ahuréi. The inhabitants of Rapa Iti speak their own Polynesian language called the |
Raivavae
Raivavae ( Tahitian: ''Ra‘ivāvae'' /ra.ʔi.va:va.e/) is one of the Austral Islands in French Polynesia )Territorial motto: ( en, "Great Tahiti of the Golden Haze") , anthem = , song_type = Regional anthem , song = " Ia Ora 'O Tahiti Nui" , image_map = French Polynesia on the globe (French Polynesia centered).svg , map_alt = Location of Frenc .... Its total land area including offshore islets is . At the 2017 census, it had a population of 903.Répartition de la population en Polynésie française en 2017 Institut de la statistique de la Polynésie française The island is of volcanic origin, and rises to elevation at Mont Hiro. History The first sighting by Europeans was recorded by the Spanish naval ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tubuai
Tubuai or Tupuai is the main island of the Austral Island group, located south of Tahiti. In addition to Tubuai, the group of islands include Rimatara, Rurutu, Raivavae, Rapa and the uninhabited Îles Maria. They are part of the Austral Islands in the far southwest of French Polynesia in the south Pacific Ocean. Tubuai island sustains a population of 2,217 people on 45 km2 of land.Répartition de la population en Polynésie française en 2017 Institut de la statistique de la Polynésie françaiseEnvironnement marin des îles Australes p. 205< ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rurutu
Rūrutu is the northernmost island in the Austral archipelago of French Polynesia, and the name of a commune consisting solely of that island. It is situated south of Tahiti. Its land area is .Environnement marin des îles Australes p. 205 It is 10.8 km long and 5.3 km wide. Its highest point (Manureva) is . At the 2017 census it had a population of 2,466.Répartition de la population en Polynésie française en 2017 Institut de la statistique de la Polynésie française Geologically, Rurutu was initially formed 12 m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rimatara
Rimatara is the westernmost inhabited island in the Austral Islands of French Polynesia. It is located south of Tahiti and west of Rurutu. The land area of Rimatara is , and that of the Maria islets is .Environnement marin des îles Australes p. 205 Its highest point is . Its population was 872 at the 2017 census.Répartition de la population en Polynésie française en 2017 Institut de la statistique de la Polynésie française Rimatara is a circular volcanic plateau surrounded by a reef with a height of . The main villages ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marotiri
Marotiri is a group of four uninhabited volcanic rocks protruding from the sea (and several submerged rocks), forming the southeastern end of the Austral Islands of French Polynesia. Marotiri is also known as Bass Rocks (''Îlots de Bass'' in French), maybe according to the name of the European explorer George Bass. Marotiri is very isolated, located about west-south-westward of Pitcairn Island. The closest island is Rapa Iti, 75 km farther northwest, but separated from it by an ocean depth of more than 1,500 meters.According to the French hydrographic office (SHOM) nautical charts 6607, there is a depth of 1,646 meters midway between Rapa and Marotiri. The rocks are part of the municipality of Rapa. The climate is wet temperate. The lower rocks are almost devoid of vegetation - although there is some vegetation on the upper slopes and summits. They are important as a seabird rookery. Fish abound in the adjacent waters. The rocks emerge from a submarine platform 100 meters ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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