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Akahoya Eruption
The Akahoya eruption or Kikai-Akahoya eruption was the strongest known volcanic eruption of the Kikai Caldera in Kyūshū, Japan occurring 5250 BCE. It ejected of volcanic material, giving it a Volcanic Explosivity Index of 7. Context The Kikai Caldera had erupted around 94,000 years before in the smaller Nagase eruption, and that was preceded around 140,000 years ago by the Koabiyama eruption. Eruption sequence There is evidence of volcanic activity at the Kikai Caldera in what is termed the K–Km tephra layers between 16–9 cal BP. The Takeshima debris avalanche followed by the Nagahama lava (NgL) and Heikejo ash (K–Hj) events preceded the eruption. The eruption proper then started with a Plinian eruption of VEI 6 (K–KyP), which ejected the Koya (Funakura) pumice fall. The sequence from then on lasted at least 28 hours. In the latter half of this Plinian eruption, the plume collapsed and an intra-plinian flow, the Funakura pyroclastic flow (K–Fn), occ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Before Present
Before Present (BP) or "years before present (YBP)" is a time scale used mainly in archaeology, geology, and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Because the "present" time changes, standard practice is to use 1January 1950 as the commencement date (epoch) of the age scale, with 1950 being labelled as the "standard year". The abbreviation "BP" has been interpreted retrospectively as "Before Physics", which refers to the time before nuclear weapons testing artificially altered the proportion of the carbon isotopes in the atmosphere, which scientists must account for when using radiocarbon dating for dates of origin that may fall after this year. In a convention that is not always observed, many sources restrict the use of BP dates to those produced with radiocarbon dating; the alternative notation "RCYBP" stands for the explicit "radio carbon years before present". Usage The BP scale is s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seawater
Seawater, or sea water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximately of dissolved salts (predominantly sodium () and chloride () ions). The average density at the surface is 1.025 kg/L. Seawater is denser than both fresh water and pure water (density 1.0 kg/L at ) because the dissolved salts increase the mass by a larger proportion than the volume. The freezing point of seawater decreases as salt concentration increases. At typical salinity, it freezes at about . The coldest seawater still in the liquid state ever recorded was found in 2010, in a stream under an Antarctic glacier: the measured temperature was . Seawater pH is typically limited to a range between 7.5 and 8.4. However, there is no universally accepted reference pH-scale for seawater and the difference between measuremen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ōsumi Peninsula
image:Osumi Peninsula Kagoshima Japan SRTM.jpg, 261x261px, Satellite image of Ōsumi Peninsula The projects south from the Japanese island of Kyūshū and includes the southernmost point on the island, Cape Sata. Its east coast lies on the Pacific Ocean, while to the west it faces the Satsuma Peninsula across Kagoshima Bay. Politically it is part of Kagoshima Prefecture. Lava erupted in 1914 by Sakurajima (previously an island) made a land connection with the northwest of the Ōsumi Peninsula. Japan's first satellite was named Ohsumi (satellite), Ohsumi in honour of the people living in the area due their support of the people working on the launch. See also *: Southernmost point References Peninsulas of Japan Landforms of Kagoshima Prefecture {{Kagoshima-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Satsuma Peninsula
The Satsuma Peninsula (薩摩半島 ''Satsuma-hantō'') is a peninsula which projects south from the southwest part of Kyūshū Island, Japan. To the west lies the East China Sea, while to the east it faces the Ōsumi Peninsula across Kagoshima Bay. Politically, it belongs to Kagoshima Prefecture, and it includes the prefectural capital, Kagoshima, Kagoshima, Kagoshima City. Near the southern tip of the peninsula is the Mount Kaimon (Kaimon-dake) and the hot springs of Ibusuki Onsen. References {{Kagoshima-geo-stub Landforms of Kagoshima Prefecture Peninsulas of Japan Satsuma Province ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ground Motion
Ground motion is the movement of the Earth’s surface from earthquakes or explosions. Ground motion is produced by seismic waves that are generated by sudden slip on a fault or sudden pressure at the explosive source and travel through the Earth and along its surface. This can be due to natural events, such as earthquakes and volcanic eruptions, or human activities, such as the detonation of nuclear weapons. There are two main types of seismic waves: body waves and surface waves. Body waves travel through the interior of the Earth, while surface waves travel along the Earth's surface. Ground motion is typically caused by surface waves, which are the most destructive type of seismic waves. Ground motion is measured using a seismometer A seismometer is an instrument that responds to ground displacement and shaking such as caused by quakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The ou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tanegashima
is one of the Ōsumi Islands belonging to Kagoshima Prefecture, Japan. The island, in area, is the second largest of the Ōsumi Islands, and has a population of 33,000 people. Access to the island is by ferry, or by air to New Tanegashima Airport. Administratively, the island is divided into the cities of Japan, city, Nishinoomote, Kagoshima, Nishinoomote, and the two towns of Japan, towns, Nakatane, Kagoshima, Nakatane and Minamitane, Kagoshima, Minamitane. The towns belong to Kumage District, Kagoshima, Kumage District. Geography Tanegashima is the easternmost and the second largest (after Yakushima) of the Ōsumi Islands. It is located approximately south of the southern tip of Ōsumi Peninsula in southern Kyushu, or south of Kagoshima, Kagoshima, Kagoshima. The Vincennes Strait (Yakushima Kaikyō) separates it from Yakushima. The island is of volcanic origin; however, unlike neighboring Yakushima, it presents a flat appearance, with its highest elevation at only above s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yakushima
is one of the Ōsumi Islands in Kagoshima Prefecture, Japan. The island, in area, has a population of 13,178. It is accessible by hydrofoil ferry, car ferry, or by air to Yakushima Airport. Administratively, the island consists of the town of Yakushima, which extends to the neighbouring island of Kuchinoerabujima. 42% of the island is within the borders of the Yakushima National Park. Yakushima's electricity is more than 50% hydroelectric, and surplus power has been used to produce hydrogen gas in an experiment by Kagoshima University. The island has been a test site for Honda's hydrogen fuel cell vehicle research. World Heritage designation In 1980, an area of was designated a UNESCO Man and the Biosphere Reserve. In 1993, of wetland at Nagata-hama was designated a Ramsar site. Yakushima is the largest nesting ground for the endangered loggerhead sea turtle in the North Pacific. The island's unique remnant of warm/temperate ancient forest has been a natural World ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Liquefaction
Soil liquefaction occurs when a cohesionless saturated or partially saturated soil substantially loses Shear strength (soil), strength and stiffness in response to an applied Shear stress, stress such as shaking during an earthquake or other sudden change in stress condition, in which material that is ordinarily a solid behaves like a liquid. In soil mechanics, the term "liquefied" was first used by Allen Hazen in reference to the 1918 failure of the Calaveras Dam in California. He described the mechanism of flow liquefaction of the embankment dam as: The phenomenon is most often observed in saturated, loose (low density or uncompacted), sandy soils. This is because a loose sand has a tendency to Compressibility, compress when a force, load is applied. Dense sands, by contrast, tend to expand in volume or 'Reynolds' dilatancy, dilate'. If the soil is saturated by water, a condition that often exists when the soil is below the water table or sea level, then water fills the gap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earthquake
An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they cannot be felt, to those violent enough to propel objects and people into the air, damage critical infrastructure, and wreak destruction across entire cities. The seismic activity of an area is the frequency, type, and size of earthquakes experienced over a particular time. The seismicity at a particular location in the Earth is the average rate of seismic energy release per unit volume. In its most general sense, the word ''earthquake'' is used to describe any seismic event that generates seismic waves. Earthquakes can occur naturally or be induced by human activities, such as mining, fracking, and nuclear weapons testing. The initial point of rupture is called the hypocenter or focus, while the ground level directly above it is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Survey Of Japan
Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth sciences, including hydrology. It is integrated with Earth system science and planetary science. Geology describes the structure of the Earth on and beneath its surface and the processes that have shaped that structure. Geologists study the mineralogical composition of rocks in order to get insight into their history of formation. Geology determines the relative ages of rocks found at a given location; geochemistry (a branch of geology) determines their Geochronology, absolute ages. By combining various petrological, crystallographic, and paleontological tools, geologists are able to chronicle the geological history of the Earth as a whole. One aspect is to demonstrate the age of the Earth. Geology provides evidence for plate tectonics, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caldera
A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the structural integrity of such a chamber, greatly diminishing its capacity to support its own roof and any substrate or rock resting above. The ground surface then collapses into the emptied or partially emptied magma chamber, leaving a large depression at the surface (from one to dozens of kilometers in diameter). Although sometimes described as a Volcanic crater, crater, the feature is actually a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Compared to the thousands of volcanic eruptions that occur over the course of a century, the formation of a caldera is a rare event, occurring only a few times within a given window of 100 years. Only eight caldera-forming collapses are known to have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Korean Peninsula
Korea is a peninsular region in East Asia consisting of the Korean Peninsula, Jeju Island, and smaller islands. Since the end of World War II in 1945, it has been politically divided at or near the 38th parallel between North Korea (Democratic People's Republic of Korea; DPRK) and South Korea (Republic of Korea; ROK). Both countries proclaimed independence in 1948, and the two countries fought the Korean War from 1950 to 1953. The region is bordered by China to the north and Russia to the northeast, across the Amnok (Yalu) and Duman (Tumen) rivers, and is separated from Japan to the southeast by the Korea Strait. Known human habitation of the Korean peninsula dates to 40,000 BC. The kingdom of Gojoseon, which according to tradition was founded in 2333 BC, fell to the Han dynasty in 108 BC. It was followed by the Three Kingdoms period, in which Korea was divided into Goguryeo, Baekje, and Silla. In 668 AD, Silla conquered Baekje and Goguryeo with the aid of the Tang dy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
