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The Benham Plateau, also known as the Benham Rise, is a seismically active undersea region and extinct volcanic ridge located in the Philippine Sea approximately east of the northern coastline of Dinapigue, Isabela. Under the Philippine Sea lie a number of basins including the ''West Philippine Basin'' (WPB), inside of which is located the ''Central Basin Fault'' (CBF). The Benham Plateau is located in the CBF and its basement probably is a micro-continent.〔 - Total pages: 440〕 Several scientific surveys have been made on the feature to study its nature and its impact on tectonic subduction, including one about its effects on the 1990 Luzon earthquake. The area is claimed, as part of its continental shelf, by the Philippines, which has lodged a claim with the United Nations Commission on the Limits of the Continental Shelf on April 8, 2009 and was approved by the United Nations Convention on the Law of the Sea (UNCLOS) in 2012.〔(【引用サイトリンク】url =http://newsinfo.inquirer.net/183779/un-approves-ph-territorial-claim-to-benham-rise )〕 ==Geological features== Benham Rise is a submerged extinct volcanic ridge located at 16 degrees 30 minutes N, 124 degrees 45 minutes E off the coast of Luzon, with the size of about 250 km in diameter and rises over 2,000 meters (2 km.) above the sea floor, from below 5,000 meters (5 km.) below sea level to above 3,000 meters (3 km.) below sea level. Its area is close to the Benham Seamount, located at 15 degrees 48 minutes N, 124 degrees 15 minutes E. The precise location is somewhere near the east of the Philippine Trench and near the south of the East Luzon Trench, both of which absorb the subducting force of the Philippine Sea Plate under the Philippine Mobile Belt,〔Hashimoto, M, ed., (1981) ''Accretion Tectonics in the Circum-Pacific Regions'', ISBN 90-277-1561-0 p299〕 a collage of large blocks of that crust that amalgamated prior to the collision of the Philippine Sea Plate with the Eurasian Plate.〔Rangin and Pubellier (1990) in ''Tectonics of Circum-Pacific Continental Margins'' ISBN 90-6764-132-4 p149〕 The origin of the landform, along with a fellow landform, the Urdaneta Plateau (a remnant of mantle plume), is identified in one study as at least five sequences of propagating rifts, probably triggered by mantle flowing away from the mantle thermal anomaly. Its presence of the landform disrupts the continuity of this region (known as the Philippine-East Luzon Trench) by continuously colliding with the Sierra Madre mountain range of eastern portion of the island of Luzon. Though it is generally thought that the Philippine Sea Plate is being subducted under the Philippine Mobile Belt, under the rules of tectonic subduction, there appears to be a resistance to this because of the presence of the landform, and instead, the plate is being displaced into the northern portion of Luzon to the west.〔Rangin and Pubellier (1990) in ''Tectonics of Circum-Pacific Continental Margins'' ISBN 90-6764-132-4, p149〕〔Deschamps and Lallemand (2003) in ''Intra-Oceanic Subduction Systems: Tectonic and Magmatic Processes'' ISBN 1-86239-147-5 p165〕 The geophysical features of the plateau may have been the result of an early Miocene collision event between the Benham Rise and the eastern margin of Luzon, which may have also allowed the inception of the NW striking strand of the Philippine fault. These forces may have impacted the shape of the island of Luzon because of the basaltic sea floor resisting the subduction that may have also cause the bending of the Philippine Fault.〔, Document ID:13258〕 The active basins in Central Luzon, which trace an asymmetrical V shape, is the best place to observe recent tectonic evolution of the fault system. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Benham Plateau」の詳細全文を読む スポンサード リンク
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