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2019 Yamagata Earthquake
The was an earthquake of magnitude 6.4 which struck primarily the Hokuriku region in Japan on 18 June 2019 at 22:22 JST (13:22 UTC). The epicenter was close to the city of Tsuruoka, Yamagata. A tsunami warning was also issued. Geology The northwestern side of Honshu lies on the southeastern margin of the Sea of Japan, an area of oceanic crust created by back-arc spreading from the late Oligocene to middle Miocene. The extensional tectonics associated with the spreading formed a series of N-S trending extensional faults and associated basins. The crust in this area is subjected to east–west compression associated with the convergent boundary between the Amur Plate and the Okhotsk Plate. As a result of this strain, the north–south trending extensional faults are reactivated in a reverse sense. The 1964 Niigata earthquake, the 1983 Sea of Japan earthquake, and the 1993 Hokkaidō earthquake were all a result of similar processes. Damage and effects The magnitude 6.4 earthq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Japan Standard Time
, or , is the standard time zone in Japan, 9 hours ahead of UTC ( UTC+09:00). Japan does not observe daylight saving time, though its introduction has been debated on several occasions. During World War II, the time zone was often referred to as Tokyo Standard Time. Japan Standard Time is equivalent to Korean Standard Time, Pyongyang Time (North Korea), Eastern Indonesia Standard Time, East-Timorese Standard Time and Yakutsk Time (Russia). History Before the Meiji era (1868–1912), each local region had its own time zone in which noon was when the sun was exactly at its culmination. As modern transportation methods, such as trains, were adopted, this practice became a source of confusion. For example, there is a difference of about 5 degrees longitude between Tokyo and Osaka and because of this, a train that departed from Tokyo would arrive at Osaka 20 minutes behind the time in Tokyo. In 1886, Ordinance 51 was issued in response to this problem, which stated: Accordi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Back-arc Spreading
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 are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1964 Niigata Earthquake
Events January * January 1 – The Federation of Rhodesia and Nyasaland is dissolved. * January 5 - In the first meeting between leaders of the Roman Catholic and Orthodox churches since the fifteenth century, Pope Paul VI and Patriarch Athenagoras I of Constantinople meet in Jerusalem. * January 6 – A British firm, the Leyland Motor Corp., announces the sale of 450 buses to the Cuban government, challenging the United States blockade of Cuba. * January 9 – ''Martyrs' Day'': Armed clashes between United States troops and Panamanian civilians in the Panama Canal Zone precipitate a major international crisis, resulting in the deaths of 21 Panamanians and 4 U.S. soldiers. * January 11 – United States Surgeon General Luther Terry reports that smoking may be hazardous to one's health (the first such statement from the U.S. government). * January 12 ** Zanzibar Revolution: The predominantly Arab government of Zanzibar is overthrown by African nationalist rebels; a Un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mainichi Shimbun
The is one of the major newspapers in Japan, published by In addition to the ''Mainichi Shimbun'', which is printed twice a day in several local editions, Mainichi also operates an English language news website called ''The Mainichi'' (previously ''Mainichi Daily News''), and publishes a bilingual news magazine, ''Mainichi Weekly''. It also publishes paperbacks, books and other magazines, including a weekly news magazine, ''Sunday Mainichi''. It is one of the four national newspapers in Japan; the other three are the ''Asahi Shimbun'', the ''Yomiuri Shimbun'' and the '' Nihon Keizai Shimbun''. The Sankei Shimbun and The ''Chunichi Shimbun'' are not currently in the position of a national newspaper despite a large circulation for the both respectively. History The history of the ''Mainichi Shinbun'' began with the founding of two papers during the Meiji period. The ''Tokyo Nichi Nichi Shimbun'' was founded first, in 1872. The ''Mainichi'' claims that it is the oldest existing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inversion (geology)
In structural geology inversion or basin inversion relates to the relative uplift of a sedimentary basin or similar structure as a result of crustal shortening. This normally excludes uplift developed in the footwalls of later extensional faults, or uplift caused by mantle plumes. "Inversion" can also refer to individual faults, where an extensional fault is reactivated in the opposite direction to its original movement. The term ''negative inversion'' is also occasionally used to describe the reactivation of reverse faults and thrusts during extension. The term "inversion" simply refers to the fact that a relatively low-lying area is uplifted – the rock sequence itself is not normally inverted. Formation Many inversion structures are caused by the direct reactivation of pre-existing extensional faults. In some cases only the deeper parts of the fault are reactivated and the shortening is accommodated over a much broader area in the shallow part of the section. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North American Plate
The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacific Plate (which borders the plate to the west). It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust. The interior of the main continental landmass includes an extensive granitic core called a craton. Along most of the edges of this craton are fragments of crustal material called terranes, which are accreted to the craton by tectonic actions over a long span of time. It is thought that much of North America west of the Rocky Mountains is composed of such terranes. Boundaries The southern boundary with the Cocos Plate to the west and the Caribbean Plate to the east is a transform fault, represented by the Swan Islands Transform Fault unde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eurasian Plate
The Eurasian Plate is a tectonic plate that includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent and the area east of the Chersky Range in eastern Siberia. It also includes oceanic crust extending westward to the Mid-Atlantic Ridge and northward to the Gakkel Ridge. The eastern edge is a boundary with the North American Plate to the north and a boundary with the Philippine Sea Plate to the south and possibly with the Okhotsk Plate and the Amurian Plate. The southern edge is a boundary with the African Plate to the west, the Arabian Plate in the middle and the Indo-Australian Plate to the east. The western edge is a divergent boundary with the North American Plate forming the northernmost part of the Mid-Atlantic Ridge, which is straddled by Iceland. All volcanic eruptions in Iceland, such as the 1973 eruption of Eldfell, the 1783 eruptio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Okhotsk Plate
The Okhotsk Plate is a minor tectonic plate covering the Kamchatka Peninsula, Magadan Oblast, and Sakhalin Island of Russia; Hokkaido, Kantō and Tōhoku regions of Japan; the Sea of Okhotsk, as well as the disputed Kuril Islands. It was formerly considered a part of the North American Plate, but recent studies indicate that it is an independent plate, bounded on the north by the North American Plate. The boundary is a left-lateral moving transform fault, the Ulakhan Fault originating from a triple junction in the Chersky Range. On the east, the plate is bounded by the Pacific Plate at the Kuril–Kamchatka Trench and the Japan Trench, on the south by the Philippine Sea Plate at the Nankai Trough, on the west by the Eurasian Plate, and on the southwest by the Amurian Plate. Geology The boundary between Okhotsk Plate and Amurian Plate might be responsible for many strong earthquakes that occurred in the Sea of Japan as well as in Sakhalin Island, such as the MW7.1 ( MS7.5 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amur Plate
The Amurian Plate (or Amur Plate; also occasionally referred to as the China Plate, not to be confused with the South China Subplate) is a minor tectonic plate in the northern and eastern hemispheres. It covers Manchuria, the Korean Peninsula, the Sea of Japan, Shikoku, Kyushu, southwest Honshu (Kansai, Chūgoku), eastern Mongolia and the south of Russian Far East. Once thought to be a part of the Eurasian Plate, the Amurian Plate is now generally considered to be a separate plate moving southeast with respect to the Eurasian Plate. The Amurian Plate is named after the Amur River, which forms the border between the Russian Far East and Northeastern China. It is bounded on the north, west, and southwest by the Eurasian Plate, on the east by the Okhotsk Plate, to the southeast by the Philippine Sea Plate along the Suruga Trough and the Nankai Trough, and the Okinawa Plate, and the Yangtze Plate.Yu. F. Malyshev, et al. Deep structure of the Amur lithospheric Plate border zone. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergent Boundary
A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more Plate tectonics, lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Wadati–Benioff zone. These collisions happen on scales of millions to tens of millions of years and can lead to volcanism, earthquakes, Orogeny, orogenesis, destruction of lithosphere, and Deformation (geology), deformation. Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, and continental-continental lithosphere. The geologic features related to convergent boundaries vary depending on crust types. Plate tectonics is driven by convection cells in the mantle. Convection cells are the result of heat generated by the radioactive decay of elements in the mantle escaping to the surface and the return of cool materials from the surfac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedimentary Basin
Sedimentary basins are region-scale depressions of the Earth's crust where subsidence has occurred and a thick sequence of sediments have accumulated to form a large three-dimensional body of sedimentary rock. They form when long-term subsidence creates a regional depression that provides Accommodation (geology), accommodation space for accumulation of sediments. Over millions or tens or hundreds of millions of years the deposition of sediment, primarily gravity-driven transportation of water-borne eroded material, acts to fill the depression. As the sediments are buried, they are subject to increasing pressure and begin the processes of compaction (geology), compaction and lithification that transform them into sedimentary rock. Sedimentary basins are created by deformation of Earth's lithosphere in diverse geological settings, usually as a result of plate tectonics, plate tectonic activity. Mechanisms of crustal deformation that lead to subsidence and sedimentary basin formati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extensional Fault
An extensional fault is a fault caused by stretching of the Earth's crust. Stretching reduces the thickness and horizontally extends portions of the crust and/or lithosphere. In most cases such a fault is also a normal fault, but may create a shallower dip usually associated with a thrust fault. Extensional faults are generally planar. If the stress field is oriented with the maximum stress perpendicular to the Earth's surface, extensional faults will create an initial dip of the associated beds of about 60° from the horizontal. The faults will typically extend down to the base of the seismogenic layer In geophysics and seismology, the seismogenic layer covers the range of depths within the crust or lithosphere in which most earthquakes originate. The thickness is heavily dependent on location. For oceanic crust, the seismogenic layer thicknes .... As crustal stretching continues, the faults will rotate, resulting in steeply-dipping fault blocks between them. See also * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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