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Resurgent Dome
In geology, a resurgent dome is a dome formed by swelling or rising of a caldera floor due to movement in the magma chamber beneath it. Unlike a lava dome, a resurgent dome is not formed by the extrusion of highly viscous lava onto the surface, but rather by the uplift and deformation of the surface itself by magma movement underground. Resurgent domes are typically found near the center of very large open calderas such as Yellowstone Caldera or Valles Caldera, and in turn such calderas are often referred to as "resurgent-type" calderas to distinguish them from the more common (but much smaller) calderas found on shield volcanoes and stratovolcanoes. The structure that makes a resurgent dome possible is a fracture zone made up of ring faults surrounded by concentric normal faults around the outside of the rings. During initial formation of the caldera these ring faults provide vents for ash-flow eruptions and are the point at which subsidence of the cauldron block occurs. Sub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toba Zoom
Toba may refer to: Languages * Toba Sur language, spoken in South America * Batak Toba, spoken in Indonesia People * Toba people, indigenous peoples of the Gran Chaco in South America * Toba Batak people, a sub-ethnic group of Batak people from North Sumatra, Indonesia * Tuoba (拓拔), an early name for a clan of the Xianbei people in ancient China * Toba Sōjō (1053–1140), Japanese astronomer and artist-monk * Emperor Toba, emperor of Japan * Toba Spitzer, lesbian rabbi in Arizona, USA * Petre Tobă (born 1964), Romanian politician * Toshimasa Toba (born 1975), Japanese footballer * Georgian Tobă (born 1989), Romanian footballer * Andreas Toba (born 1990), German gymnast Places * Toba, an area in Northern Sumatra that is now included in the Toba Samosir Regency ** Lake Toba, a lake in northern Sumatra, Indonesia, and site of the volcanic Toba eruption 75,000 years ago ** Toba catastrophe theory, according to which modern human evolution was affected by the Toba eruption * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Hazards
A volcanic hazard is the probability a volcanic eruption or related geophysical event will occur in a given geographic area and within a specified window of time. The risk that can be associated with a volcanic hazard depends on the proximity and vulnerability of an asset or a population of people near to where a volcanic event might occur. Lava flows Different forms of effusive lava can provide different hazards. Pahoehoe lava is smooth and ropy while Aa lava is blocky and hard. Lava flows normally follow the topography, sinking into depressions and valleys and flowing down the volcano. Lava flows will bury roads, farmlands and other forms of personal property. This lava could destroy homes, cars, and lives standing in the way. Lava flows are dangerous, however, they are slow moving and this gives people time to respond and evacuate out of immediate areas. People can mitigate this hazard by not moving to valleys or depressed areas around a volcano. Pyroclastic materials (tephra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oasis Valley
Oasis Valley is a valley in the Amargosa Desert near Beatty in Nye County, western Nevada. The valley forms part of the southern drainage of Pahute Mesa. The Amargosa River flows through the Oasis Valley between the Bare Mountains and the Bullfrog Hills to the Amargosa Valley. Natural history Oasis Valley is a portion of the Upper Amargosa Watershed. It includes geologic features of the Timber Mountain-Oasis Valley caldera complex of the Southwest Nevada volcanic field. The Amargosa Toad is endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ... to the Oasis Valley section of the Amargosa River, with its threatened population being successfully increased by local citizen efforts. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
La Garita Caldera
La Garita Caldera is a large caldera in the San Juan volcanic field in the San Juan Mountains near the town of Creede in southwestern Colorado, United States. It is west of La Garita, Colorado. The eruption that created the La Garita Caldera is among the largest known volcanic eruptions in Earth's history, as well as being one of the most powerful known supervolcanic events. Date The La Garita Caldera is one of a number of calderas that formed during a massive ignimbrite flare-up in Colorado, Utah and Nevada from 40–18 million years ago, and was the site of massive eruptions about , during the Oligocene Epoch. Area devastated The area devastated by the La Garita eruption is thought to have covered a significant portion of what is now Colorado. The deposit, known as the Fish Canyon Tuff, covered at least . Its average thickness is . The eruption might have formed a large-area ash-fall, but none has yet been identified. Size of eruption The scale of La Garita volcanism ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iwo Jima
Iwo Jima (, also ), known in Japan as , is one of the Japanese Volcano Islands and lies south of the Bonin Islands. Together with other islands, they form the Ogasawara Archipelago. The highest point of Iwo Jima is Mount Suribachi at high. Although south of the metropolis of Tokyo on the mainland, this island of 21 km2 (8 square miles) is administered as part of the Ogasawara Subprefecture of Tokyo. Since July 1944, when all the civilians were forcibly evacuated, the island has had a military-only population. The island was the location of the Battle of Iwo Jima between February 1945 and March 1945. This engagement saw some of the fiercest fighting of the Pacific War, with each side suffering over 20,000 casualties in the battle. The island became globally recognized when Joe Rosenthal, of the Associated Press, published his photograph '' Raising the Flag on Iwo Jima'', taken on Mount Suribachi. The US military occupied Iwo Jima until 1968, when it was returned to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Taupō
Lake Taupō (also spelled Taupo; mi, Taupō-nui-a-Tia or ) is a large crater lake in New Zealand's North Island, located in the caldera of the Taupō Volcano. The lake is the namesake of the town of Taupō, which sits on a bay in the lake's northeastern shore. With a surface area of , it is the largest lake by surface area in New Zealand, and the second largest freshwater lake by surface area in geopolitical Oceania after Lake Murray in Papua New Guinea. Motutaiko Island lies in the southeastern area of the lake. Lake Taupō has a perimeter of approximately and a maximum depth of . It is drained by the Waikato River (New Zealand's longest river), and its main tributaries are the Waitahanui River, the Tongariro River, and the Tauranga Taupō River. It is a noted trout fishery with stocks of introduced brown and rainbow trout. The level of the lake is controlled by Mercury Energy, the owner of the eight hydroelectric dams on the Waikato River downstream of Lake Tau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blake River Megacaldera Complex
The Blake River Megacaldera Complex is a giant subaqueous caldera cluster or a nested caldera system that spans across the Ontario–Quebec border in Canada. The caldera complex is around 2.7 billion years old, consisting of a series of overlapping calderas of various ages and sizes. It lies within the southern zone of the Abitibi greenstone belt of the Superior Craton and has an area of . The Blake River Megacaldera Complex has been a centre of major interest since 2006 with numerous excursions at the international, national and local level.ASH FALL: Newsletter of the Volcanology and Igneous Petrology Division Geological Association of Canada Retrieved on 2007-09-21 It is a world-class [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bennett Lake Volcanic Complex
The Bennett Lake Volcanic Complex (BLVC) is a huge 50-million-year-old extinct caldera complex that spans across the British Columbia-Yukon border in Canada. It is located near the western end of the West Arm of Bennett Lake. The caldera complex is surrounded by granitic rocks containing pendants. It is located near the eastern contact of the Coast Plutonic Complex and the Whitehorse Trough. There are thick series of pyroclastic and epiclastic rocks at the caldera. Remnants of this huge caldera complex are preserved near Bennett Lake in the Coast Mountains. The complex compose the Skukum Group. Formation and eruptive history The Bennett Lake Volcanic Complex was formed when the ancient Kula Plate was subducting under North America during the early Eocene period. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Toba
Lake Toba ( id, Danau Toba) ( Toba Batak: ᯖᯀᯬ ᯖᯬᯅ; romanized: ''Tao Toba'') is a large natural lake in North Sumatra, Indonesia, occupying the caldera of a supervolcano. The lake is located in the middle of the northern part of the island of Sumatra, with a surface elevation of about , the lake stretches from to . The lake is about long, wide, and up to deep. It is the largest lake in Indonesia and the largest volcanic lake in the world. Toba Caldera is one of twenty Geoparks in Indonesia, and was recognised in July 2020 as one of the UNESCO Global Geoparks. Lake Toba is the site of a supervolcanic eruption estimated at VEI 8 that occurred 69,000 to 77,000 years ago, representing a climate-changing event. Recent advances in dating methods suggest a more accurate identification of 74,000 years ago as the date. It is the largest-known explosive eruption on Earth in the last 25 million years. According to the Toba catastrophe theory, it had global consequences fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Long Valley Caldera
Long Valley Caldera is a depression in eastern California that is adjacent to Mammoth Mountain. The valley is one of the Earth's largest calderas, measuring about long (east-west), wide (north-south), and up to deep. Long Valley was formed 760,000 years ago when a very large eruption released hot ash that later cooled to form the Bishop tuff that is common to the area. The eruption emptied the magma chamber under the area to the point of collapse. The second phase of the eruption released pyroclastic flows that burned and buried thousands of square miles. Ash from this eruption blanketed much of the western part of what is now the United States. Geography The caldera is a giant bowl-shaped depression, approximately wide, surrounded by mountains except to the southeast. The elevation of the bottom of the bowl ranges from , being higher in the west. Near the center of the bowl, there is a resurgent dome formed by magmatic uplift. The southeastern slope from the caldera d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratovolcano
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and periodic intervals of explosive eruptions and effusive eruptions, although some have collapsed summit craters called calderas. The lava flowing from stratovolcanoes typically cools and hardens before spreading far, due to high viscosity. The magma forming this lava is often felsic, having high-to-intermediate levels of silica (as in rhyolite, dacite, or andesite), with lesser amounts of less-viscous mafic magma. Extensive felsic lava flows are uncommon, but have travelled as far as . Stratovolcanoes are sometimes called composite volcanoes because of their composite stratified structure, built up from sequential outpourings of erupted materials. They are among the most common types of volcanoes, in contrast to the less common shield volcano ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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