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Aleutian Megathrust
The Aleutian Trench (or Aleutian Trough) is an oceanic trench along a convergent plate boundary which runs along the southern coastline of Alaska and the Aleutian islands. The trench extends for from a triple junction in the west with the Ulakhan Fault and the northern end of the Kuril–Kamchatka Trench, to a junction with the northern end of the Queen Charlotte Fault system in the east. It is classified as a "marginal trench" in the east as it runs along the margin of the continent. The subduction along the trench gives rise to the Aleutian Arc, a volcanic island arc, where it runs through the open sea west of the Alaska Peninsula. As a convergent plate boundary, the trench forms part of the boundary between two tectonic plates. Here, the Pacific plate is being subducted under the North American plate at a dip angle of nearly 45°. The rate of closure is per year. The Pacific plate subducting under the North American plate, leads to increased faulting. This subduction beg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nanotesla
The tesla (symbol: T) is the unit of magnetic flux density (also called magnetic B-field strength) in the International System of Units (SI). One tesla is equal to one weber per square metre. The unit was announced during the General Conference on Weights and Measures in 1960 and is named in honour of Serbian-American electrical and mechanical engineer Nikola Tesla, upon the proposal of the Slovenian electrical engineer France Avčin. Definition A particle, carrying a charge of one coulomb (C), and moving perpendicularly through a magnetic field of one tesla, at a speed of one metre per second (m/s), experiences a force with magnitude one newton (N), according to the Lorentz force law. That is, \mathrm. As an SI derived unit, the tesla can also be expressed in terms of other units. For example, a magnetic flux of 1 weber (Wb) through a surface of one square meter is equal to a magnetic flux density of 1 tesla.''The International System of Units (SI), 8th edition' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hawaiian Islands
The Hawaiian Islands () are an archipelago of eight major volcanic islands, several atolls, and numerous smaller islets in the Pacific Ocean, North Pacific Ocean, extending some from the Hawaii (island), island of Hawaii in the south to northernmost Kure Atoll. Formerly called the Sandwich Islands by Europeans, the present name for the archipelago is derived from the name of its largest island, Hawaii. The archipelago sits on the Pacific Plate. The islands are exposed peaks of a great undersea mountain range known as the Hawaiian–Emperor seamount chain, formed by volcano, volcanic activity over the Hawaiian hotspot. The islands are about from the nearest continent and are part of the Polynesia subregion of Oceania. The U.S. state of Hawaii occupies the archipelago almost in its entirety (including the mostly uninhabited Northwestern Hawaiian Islands), with the sole exception of Midway Atoll (a United States Minor Outlying Island). Hawaii is the only U.S. state that is sit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Umnak Island
Umnak (; ) is one of the Fox Islands of the Aleutian Islands. With of land area, it is the third largest island in the Aleutian archipelago and the 19th largest island in the United States. The island is home to a large volcanic caldera on Mount Okmok and the only field of geysers in Alaska. It is separated from Unalaska Island by Umnak Pass. In 2000, Umnak was permanently inhabited by only 39 people and by 2010, around 18, placing the settlement of Nikolski in difficulty and its school was closed. History The earliest known settlement on Umnak Island is at Anangula and is 8,400 years old. Anangula was later abandoned and the Sandy Beach site became occupied, along with Idaliuk and Chaluka. Most of the early settlements on Umnak were located along the streams. A major geologic event was the cutting of strand flats during the Hypsithermal period, about 8250 to 3000 years ago, which led to a greater natural food supply on the island for the settlers. Umnak Island was first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adak Island
Adak Island (, ; ) or Father Island is an island near the western extent of the Andreanof Islands group of the Aleutian Islands in Alaska. Alaska's southernmost city, Adak, is located on the island. The island has a land area of , measuring long and wide, making it the 25th largest island in the United States. Due to harsh winds, frequent cloud cover, and cold temperatures, vegetation is mostly tundra (grasses, mosses, berries, low-lying flowering plants) at lower elevations. The highest point is Mount Moffett, near the northwest end of the island, at an elevation of 3,924 feet (1,196 m). It is snow covered the greater part of the year. Adak is its largest and principal city. The word ''Adak'' is from the Aleut word ''adaq'', which means "father". History Adak Island has been the home to Aleut peoples since antiquity. Russian explorers in the 18th century also visited the island but made no permanent settlements. During World War II, the Imperial Japanese Army took contro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andreanof Islands
The Andreanof Islands (, ) are a group of islands in the Aleutian Islands in southwestern Alaska, United States. They are located at about 52° North and 172°57' to 179°09' West. Geography The Andreanof Islands are located between Amchitka Pass and the Rat Islands group to the west, and Amukta Pass and the Islands of Four Mountains group to the east. The islands extend about 275 miles (440 km). The total land area of all islands (including the Delarof Islands) is 1,515.349 sq mi (3,924.737 km2). The total population was 412 persons as of the 2000 census, the vast majority in the city of Adak on Adak Island. Islands The Delarof Islands are a subgroup of the Andreanof Islands group as well as the westernmost islands in the group. The largest islands in the group are, from west to east, Gareloi Island, Tanaga Island, Kanaga, Adak Island, Kagalaska Island, Great Sitkin Island, Atka Island, Amlia, and Seguam Island. The islands are usually foggy and treele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1957 Andreanof Islands Earthquake
The 1957 Andreanof Islands earthquake occurred at 04:22 local time on March 9 with a moment magnitude scale, moment magnitude estimated at 8.6 and a maximum Modified Mercalli intensity scale, Modified Mercalli intensity of VIII (''Severe''). It occurred south of the Andreanof Islands group, which is part of the Aleutian Islands arc. The event occurred along the Aleutian Trench, the Convergent boundary, convergent plate boundary that separates the Pacific plate and the North American plates near Alaska. A basin-wide tsunami followed, with effects felt in Alaska and Hawaii, and strong waves recorded across the Pacific rim. Total losses were around United States dollar, $5 million (). Tectonic setting The Aleutian Islands lie between Kamchatka and mainland Alaska. They were formed as the result of the long convergent boundary that accommodates the subduction of the oceanic Pacific plate underneath the continental North American plate. This oceanic trench runs from the Kuril-Kamchat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hilo, Hawaii
Hilo () is the largest settlement in and the county seat of Hawaii County, Hawaiʻi, United States, which encompasses the Island of Hawaiʻi, and is a census-designated place (CDP). The population was 44,186 according to the 2020 census. It is the fourth-largest settlement in the state of Hawaiʻi, the largest settlement in the state outside of Oahu, and the largest settlement in the state outside of the Greater Honolulu Area. Hilo is in the District of South Hilo. The city overlooks Hilo Bay and has views of two shield volcanoes, Mauna Loa, an active volcano, and Mauna Kea, a dormant volcano. The Hilo bayfront has been destroyed by tsunamis twice. The majority of human settlement in Hilo stretches from Hilo Bay to Waiākea-Uka, on the flanks of the volcanoes. Hilo is home to the University of Hawaii at Hilo, ʻImiloa Astronomy Center, as well as the Merrie Monarch Festival, a week-long celebration, including three nights of competition, of ancient and modern hula th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scotch Cap Light
The Scotch Cap Light is a series of lighthouses located on the southwest corner of Unimak Island in Alaska. It was the first station established on the outside coast of Alaska. History The Scotch Cap Light was built in 1903 as a 45-foot (14 meter) wood tower on an octagonal wooden building. According to the Coast Guard Historian's Office, the lighthouse was witness to several shipwrecks. In 1909, the cannery supply ship ''Columbia'' wrecked. The 194 crew members were guests of the keepers for two weeks before a rescue ship could remove them. In 1930, the Japanese freighter ''Koshun Maru'' became lost in a snowstorm and beached near the light. In 1940, a new concrete reinforced lighthouse and fog-signal building was erected near the site of the original lighthouse. In 1942, the Russian freighter ''Turksib'' wrecked near the station. The 60 survivors lived at the station for several weeks because rough seas prevented a rescue ship from reaching the station. The 1940 aid to navigati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unimak Island
Unimak Island (, ) is the largest island in the Aleutian Islands chain of the U.S. state of Alaska. Geography It is the easternmost island in the Aleutians and, with an area of , the 9th largest island in the United States and the 134th largest island in the world. It is home to Mount Shishaldin, one of the ten most active volcanoes in the world. According to the United States Census Bureau, 64 people were living on Unimak as of the 2000 census, all of them in the city of False Pass at the eastern end of the island. Cape Lutke is a headland on the island. Cape Pankof is located at the extreme southwest of the island. The Fisher Caldera is a volcanic crater in the west-central part of Unimak. Some characteristics include many volcanic cones and undrained lakes. It is named for Bernard Fisher, a U.S. Geological Survey geologist who was killed in Umnak Pass. Mount Westdahl, in elevation, is a stratovolcano of the Aleutian Range on the island situated at its western end. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moment Magnitude Scale
The moment magnitude scale (MMS; denoted explicitly with or Mwg, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. was defined in a 1979 paper by Thomas C. Hanks and Hiroo Kanamori. Similar to the local magnitude scale, local magnitude/Richter scale () defined by Charles Francis Richter in 1935, it uses a logarithmic scale; small earthquakes have approximately the same magnitudes on both scales. Despite the difference, news media often use the term "Richter scale" when referring to the moment magnitude scale. Moment magnitude () is considered the authoritative magnitude scale for ranking earthquakes by size. It is more directly related to the energy of an earthquake than other scales, and does not saturatethat is, it does not underestimate magnitudes as other scales do in certain conditions. It has become the standard scale used by seismological authorities like the United State ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1946 Aleutian Islands Earthquake
The 1946 Aleutian Islands earthquake occurred near the Aleutian Islands, Alaska on April 1, 1946. The shock measured () 8.6, 9.3 or () 7.4. It had a maximum Mercalli intensity of VI (''Strong''). It resulted in 165–173 casualties and over US$26 million () in damage. The seafloor along the fault was elevated, triggering a Pacific-wide tsunami with multiple destructive waves at heights ranging from . The tsunami obliterated the Scotch Cap Lighthouse on Unimak Island, Alaska among others, and killed all five lighthouse keepers. Despite the destruction to the Aleutian Island Unimak, the tsunami had almost an imperceptible effect on the Alaskan mainland. Tectonic setting The Aleutian Islands are a group of 14 large and 55 smaller volcanic islands situated between mainland Alaska and Kamchatka. They are situated along the Aleutian Trench as they were formed by the active subduction of the oceanic Pacific plate underneath the continental crust of the North American plate. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
