1.
Hawaiian Islands
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Formerly the group was known to Europeans and Americans as the Sandwich Islands, a name chosen by James Cook in honor of the then First Lord of the Admiralty John Montagu, 4th Earl of Sandwich. The contemporary name is derived from the name of the largest island, the Hawaiian monarchy was overthrown in 1893 and the United States annexed the islands in 1898. The Hawaiian Islands are the peaks of a great undersea mountain range known as the Hawaiian–Emperor seamount chain. The islands are about 1,860 miles from the nearest continent and this name was in use until the 1840s, when the local name Hawaii gradually began to take precedence. The Hawaiian Islands have a land area of 6,423.4 square miles. Except for Midway, which is a territory of the United States. The eight main islands of Hawaii are listed here and this number includes all minor islands and islets, or very small island, offshore of the main islands and individual islets in each atoll. Thus, the southeast island is volcanically active, whereas the islands on the northwest end of the archipelago are older and typically smaller, the age of the archipelago has been estimated using potassium-argon dating methods.4 Ma. The only active volcanism in the last 200 years has been on the island, Hawaiʻi. The Hawaiian Volcano Observatory of the USGS documents recent volcanic activity and provides images, almost all of the magma of the hotspot has the composition of basalt, and so the Hawaiian volcanoes are composed almost entirely of this igneous rock. There is very little coarser-grained gabbro and diabase, nephelinite is exposed on the islands but is extremely rare. Hawaiʻi island is the biggest and youngest island in the chain, mauna Loa, taking up over half of the Big Island, is the largest shield volcano on the Earth. The measurement from sea level to summit is more than 2.5 miles, the Hawaiian Islands have many earthquakes, generally caused by volcanic activity. Most of the earthquake monitoring took place in Hilo, by missionaries Titus Coan, Sarah J. Lyman. From 1833 to 1896, approximately 4 or 5 earthquakes were reported per year, Hawaii accounted for 7. 3% of the United States reported earthquakes with a magnitude 3.5 or greater from 1974 to 2003, with a total 1533 earthquakes. Hawaii ranked as the state with the third most earthquakes over this period, after Alaska. On October 15,2006, there was an earthquake with a magnitude of 6.7 off the northwest coast of the island of Hawaii, the initial earthquake was followed approximately five minutes later by a magnitude 5.7 aftershock. Minor-to-moderate damage was reported on most of the Big Island, several major roadways became impassable from rock slides, and effects were felt as far away as Honolulu, Oahu, nearly 150 miles from the epicenter
2.
Island
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An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, skerries, an island in a river or a lake island may be called an eyot or ait, and a small island off the coast may be called a holm. A grouping of geographically or geologically related islands is called an archipelago, an island may be described as such, despite the presence of an artificial land bridge. Example, Singapore and its causeway, or the various Dutch delta islands, there are two main types of islands in the sea, continental and oceanic. The word island derives from Middle English iland, from Old English igland, Old English ieg is actually a cognate of Swedish ö and German Aue, and related to Latin aqua. There is a difference between islands and continents in terms of geology, continents sit on continental lithosphere which is part of tectonic plates floating high on Earths mantle. Oceanic crust is also part of tectonic plates, but it is denser than continental lithosphere, Islands are either extensions of the oceanic crust or geologically they are part of some continent sitting on continental lithosphere. This holds true for Australia, which sits on its own continental lithosphere, continental islands are bodies of land that lie on the continental shelf of a continent. A special type of island is the microcontinental island, which is created when a continent is rifted. Examples are Madagascar and Socotra off Africa, the Kerguelen Islands, New Caledonia, New Zealand, another subtype is an island or bar formed by deposition of tiny rocks where water current loses some of its carrying capacity. While some are transitory and may disappear if the volume or speed of the current changes, others are stable, oceanic islands are islands that do not sit on continental shelves. The vast majority are volcanic in origin, such as Saint Helena in the South Atlantic Ocean, the few oceanic islands that are not volcanic are tectonic in origin and arise where plate movements have lifted up the ocean floor above the surface. Examples are Saint Peter and Paul Rocks in the Atlantic Ocean, one type of volcanic oceanic island is found in a volcanic island arc. These islands arise from volcanoes where the subduction of one plate under another is occurring, examples are the Aleutian Islands, the Mariana Islands, and most of Tonga in the Pacific Ocean. The only examples in the Atlantic Ocean are some of the Lesser Antilles, another type of volcanic oceanic island occurs where an oceanic rift reaches the surface. There are two examples, Iceland, which is the second largest volcanic island, and Jan Mayen. A third type of oceanic island is formed over volcanic hotspots. A hotspot is more or less stationary relative to the tectonic plate above it
3.
Kauai
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For the Childish Gambino EP see STN MTN / Kauai Kauaʻi or Kauai is geologically the oldest of the main Hawaiian Islands. With an area of 562.3 square miles, it is the fourth largest of these islands, known also as the Jurassic Isle, Kauaʻi lies 105 miles across the Kauaʻi Channel, northwest of Oʻahu. This island is the site of Waimea Canyon State Park, the United States Census Bureau defines Kauaʻi as census tracts 401 through 409 of Kauaʻi County, Hawaiʻi, which comprises all of the county except for the islands of Kaʻula, Lehua and Niʻihau. The 2010 United States Census population of the island was 67,091, the most populous town was Kapaʻa. Hawaiian narrative locates the origin in the legend of Hawaiʻiloa. The story relates how he named the island of Kauaʻi after a favorite son, another possible translation is food season. Kauaʻi was known for its dialect of the Hawaiian language. While the standard language today adopts the dialect of Hawaiʻi island, which has the sound, in effect, Kauaʻi dialect retained the old pan-Polynesian /t/, while standard Hawaiʻi dialect has changed it to the. Therefore, the name for Kauaʻi was said as Tauaʻi. Kauaʻis origins are volcanic, the island having been formed by the passage of the Pacific Plate over the Hawaii hotspot, at approximately six million years old, it is the oldest of the main islands. The highest peak on this island is Kawaikini at 5,243 feet. The second highest peak is Mount Waiʻaleʻale near the center of the island,5,148 feet above sea level, one of the wettest spots on earth, with an annual average rainfall of 1,170 centimetres, is located on the east side of Mount Waiʻaleʻale. The high annual rainfall has eroded deep valleys in the central mountains, at 3,000 feet deep, Waimea Canyon is often referred to as The Grand Canyon of the Pacific. Kokeo Point lies on the side of the island. The Na Pali Coast is a center for recreation in a setting, including kayaking past the beaches. The headland, Kuahonu Point, is on the south-east of the island, Kauaʻi’s climate is tropical, with generally humid and stable conditions year round, although weather phenomena and infrequent storms have caused instances of extreme weather. At the lower elevations the annual precipitation varies from an average of about 50 inches on the windward shore, average temperature in Lihue, the county seat, ranges from 78 °F in February to 85 °F in August and September. Kauaʻi’s mountainous regions offer cooler temperatures and provide a pleasant contrast to the coastal areas
4.
Niihau
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Niʻihau is the westernmost and seventh largest inhabited island in Hawaiʻi. It is 17.5 miles southwest of Kauaʻi across the Kaulakahi Channel and its area is 69.5 square miles. Several intermittent playa lakes provide wetland habitats for the Hawaiian coot, the black-winged stilt, the island is designated as critical habitat for Brighamia insignis, an endemic and endangered species of Hawaiian lobelioid. The United States Census Bureau defines Niʻihau and the island and State Seabird Sanctuary of Lehua as Census Tract 410 of Kauai County. Its 2000 census population was 160, Its 2010 census population was 170, elizabeth Sinclair purchased Niʻihau in 1864 for $10,000 from the Kingdom of Hawaii and private ownership passed on to her descendants, the Robinson family. During World War II, the island was the site of the Niʻihau Incident, A Japanese navy fighter pilot crashed on the island, the people of Niʻihau are known for their gemlike lei pūpū craftsmanship, and speak Hawaiian as a primary language. The island is generally off-limits to all but relatives of the owners, U. S. Navy personnel, government officials and invited guests. Beginning in 1987, a number of supervised activity tours. The island is managed by brothers Bruce Robinson and Keith Robinson. Niʻihau is located about 18 miles west of Kauaʻi, and the tiny, Niʻihaus dimensions are 6.2 miles by 18.6 miles. The maximum elevation is 1,280 feet, the island is about 4.9 million years old, making it geologically younger than the 5-million-year-old neighboring island of Kauaʻi to the northeast. Niʻihau consists of one extinct volcano that had a landslide to the east. The island is relatively arid because it lies in the shadow of Kauaʻi. Niʻihau therefore, depends for its rain on winter Kona storms, as such, the island is subject to long periods of drought. As an arid island, Niʻihau was barren of trees for centuries — Captain James Cook reported it treeless in 1778, island co-owner Keith Robinson, a noted conservationist, preserved and documented many of Niʻihaus natural plant resources. The island is designated as a habitat for the ʻōlulu. Aylmer robinsonii, a Pritchardia palm tree named for Keith Robinsons uncle Aylmer Robinson, is a species native to Niʻihau. Several bird species thrive on Niʻihau, intermittent playa lakes on the island provide wetland habitats for the ʻalae keʻokeʻo, the āeʻo, and the koloa maoli
5.
Honolulu County, Hawaii
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Honolulu County is a consolidated city–county located in the U. S. state of Hawaii. The consolidated city-county was established in the city adopted in 1907. As a municipal corporation and jurisdiction it manages aspects of government traditionally exercised by municipalities and counties in the rest of the United States. As of the 2010 census, the population was 953,207, because of Hawaiis municipal structure, the United States Census Bureau divides Honolulu County into several census-designated places for statistical purposes. The current mayor of Honolulu County is Kirk Caldwell, who reclaimed the job from the person who defeated him in a 2010 special election, Peter Carlisle, the county motto is Haʻaheo No ʻO Honolulu. Approximately 70% of the population lives in Honolulu County. Only Nevada has a percentage of its population living in its most populous county. According to the U. S. Census Bureau, the county has an area of 2,128 square miles. However, the majority of area is the Pacific Ocean that surrounds the islands. For 2013, the county has an operating budget of US$2.16 billion. The government of Honolulu County is simplified and streamlined and coalesces at three major divisions of municipal power, the mayor of Honolulu is the principal executor of administrative authority. The mayor is elected on a basis to a four-year term. The Honolulu City Council is the legislative body. Its elected members are responsible for drafting and passing laws, as well as proposing budgets for various departments, unlike other cities in the United States, the council is absolutely independent of the mayor, who does not make any appearances during any of the council sessions. The nine council members represent one of nine districts, and are elected on a non-partisan basis to staggered four-year terms. The Prosecuting Attorney of Honolulu is independently elected of the two major divisions of municipal power, and is charged with prosecuting criminal offenses committed within the county. The office is not charged with providing legal counsel to the mayor or City Council, the prosecuting attorney is elected on a non-partisan basis to a four-year term. The Honolulu County is divided into 36 neighborhood boards, the office of neighborhood board member is an advisory position for public policy and civil investment
6.
Hawaii
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Hawaii is the 50th and most recent state to have joined the United States of America, having received statehood on August 21,1959. Hawaii is the only U. S. state located in Oceania and it is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean. Hawaii is the only U. S. state not located in the Americas, the state encompasses nearly the entire volcanic Hawaiian archipelago, which comprises hundreds of islands spread over 1,500 miles. At the southeastern end of the archipelago, the eight main islands are—in order from northwest to southeast, Niʻihau, Kauaʻi, Oʻahu, Molokaʻi, Lānaʻi, Kahoʻolawe, Maui, and the Island of Hawaiʻi. The last is the largest island in the group, it is called the Big Island or Hawaiʻi Island to avoid confusion with the state or archipelago. The archipelago is physiographically and ethnologically part of the Polynesian subregion of Oceania, Hawaii has over a million permanent residents, along with many visitors and U. S. military personnel. Its capital is Honolulu on the island of Oʻahu, Hawaii is the 8th-smallest and the 11th-least populous, but the 13th-most densely populated of the fifty U. S. states. It is the state with an Asian plurality. The states coastline is about 750 miles long, the fourth longest in the U. S. after the coastlines of Alaska, Florida, the state of Hawaii derives its name from the name of its largest island, Hawaiʻi. A common Hawaiian explanation of the name of Hawaiʻi is that was named for Hawaiʻiloa and he is said to have discovered the islands when they were first settled. The Hawaiian language word Hawaiʻi is very similar to Proto-Polynesian *Sawaiki, cognates of Hawaiʻi are found in other Polynesian languages, including Māori, Rarotongan and Samoan. According to linguists Pukui and Elbert, lsewhere in Polynesia, Hawaiʻi or a cognate is the name of the underworld or of the home, but in Hawaii. A somewhat divisive political issue arose in 1978 when the Constitution of the State of Hawaii added Hawaiian as an official state language. The title of the constitution is The Constitution of the State of Hawaii. Article XV, Section 1 of the Constitution uses The State of Hawaii, diacritics were not used because the document, drafted in 1949, predates the use of the okina and the kahakō in modern Hawaiian orthography. The exact spelling of the name in the Hawaiian language is Hawaiʻi. In the Hawaii Admission Act that granted Hawaiian statehood, the government recognized Hawaii as the official state name. Official government publications, department and office titles, and the Seal of Hawaii use the spelling with no symbols for glottal stops or vowel length
7.
Midway Atoll
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Midway Atoll is a 2. 4-square-mile atoll in the North Pacific Ocean at 28°12′N 177°21′W. As its name suggests, Midway is roughly equidistant between North America and Asia, Midway Atoll is an unorganized, unincorporated territory of the United States. Midway continues to be the island in the Hawaiian archipelago that is not part of the state of Hawaii. Unlike the other Hawaiian islands, Midway observes Samoa Time, which is one hour behind the time in the state of Hawaii, for statistical purposes, Midway is grouped as one of the United States Minor Outlying Islands. The Midway Atoll National Wildlife Refuge, encompassing 590,991.50 acres of land and water in the area, is administered by the United States Fish. The refuge and most of its area are part of the larger Papahānaumokuākea Marine National Monument. Until 1993, the atoll was the home of the Naval Air Facility Midway, the Battle of Midway, which was fought between June 4 and 6,1942, was one of the most important battles of the Pacific campaign of World War II. The United States Navy defeated a Japanese battle group marking a point in the war in the Pacific Theater. USAAF aircraft based at the original Henderson Field on Eastern Island joined the attack against the Japanese fleet, approximately 40 to 60 people live on the atoll, which includes staff of the US Fish and Wildlife Service and contract workers. At present, visitation to the atoll is only for business reasons as the tourism program has been suspended due to budget cutbacks. In 2012, the last year that the program was in operation,332 people made the trip to Midway. Tours focused on both the ecology of Midway as well as its military history. The economy is derived solely from governmental sources and tourist fees, nearly all supplies must be brought to the island by ship or plane, though a hydroponic greenhouse and garden supply some fresh fruits and vegetables. As its name suggests, Midway is roughly equidistant between North America and Asia, and lies almost halfway around the world longitudinally from Greenwich and it is near the northwestern end of the Hawaiian archipelago, about one-third of the way from Honolulu, Hawaii, to Tokyo, Japan. Midway Atoll is less than 140 nautical miles east of the International Date Line, about 2,800 nautical miles west of San Francisco, and 2,200 nautical miles east of Tokyo. Midway Atoll is part of a chain of islands, atolls. It consists of a barrier reef and several sand islets. The two significant pieces of land, Sand Island and Eastern Island, provide a habitat for millions of seabirds
8.
Necker Island (Hawaii)
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Necker Island is a small island in the Northwestern Hawaiian Islands. It is located at 23°34′35″N 164°42′0″W in the Pacific Ocean,155 miles northwest of Nihoa and 8 miles north of the Tropic of Cancer. It contains important prehistoric sites of the Hawaiian culture and is part of the Hawaiian Islands National Wildlife Refuge within the Northwestern Hawaiian Islands National Monument. The United States Census Bureau reports its land area as 45.193 acres, the island is rocky with steep sides and has very little soil. Its highest elevation is 277 feet, the island is named after Jacques Necker, a finance minister of Louis XVI. Few signs of human habitation have been found. However, the island contains 33 stone shrines and stone artifacts much like those found in the main Hawaiian Islands, because of this, many anthropologists believe that the island was a ceremonial and religious site. According to the myths and legends of the people of Kauai, according to the legend, the Menehune settled on Necker after being chased off Kauai by the stronger Polynesians and subsequently built the various stone structures there. Visits to the island are said to have started a few hundred years after the main Hawaiian Islands were inhabited, french explorer Jean-François de La Pérouse was the first European to visit the island, in 1786. The island is named after Jacques Necker, the islands were formally annexed in 1894 by the Provisional Government of Hawaii. Because of the usage by Native Hawaiians as a ceremonial and religious site in Ancient Hawaii. List of volcanoes in the Hawaiian – Emperor seamount chain Evenhuis, Neal L. Eldredge, natural History of Nihoa and Necker Islands. Bishop Museum Bulletin in Cultural and Environmental Studies, No.1, the Columbia Gazetteer of North America. Archived from the original on 2002-03-29
9.
Laysan
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Laysan, located 808 nautical miles northwest of Honolulu at N25°4214 W171°4404, is one of the Northwestern Hawaiian Islands. It comprises one land mass of 1,016 acres, about 1 by 1 1⁄2 miles in size. It is an atoll of sorts, although the land completely surrounds a central lake some 8 feet above sea level that has a salinity approximately three times greater than the ocean. Laysans Hawaiian name of Kauō means egg, referring to its shape, Laysan is the second largest single landmass in the Northwestern Hawaiian Islands, after Sand Island at Midway Atoll. Laysan was created by growth and geologic upshift. The fringing reefs surrounding the island cover about 735 acres, Lake Laysan, the 100 acres, brown, hypersaline lake in the islands interior, has varied in depth over the decades. In the 1860s, the lake was at most 30 feet deep, the best way to find fresh water on Laysan is to observe where the finches are drinking, the fresh water floats on the saltier water and accumulates around the shore. The tallest point on the island is at 50 feet above sea level, a U. S. Geological Survey study found that Laysan, Midway Atoll, and Pacific islands like them could become inundated and unfit to live on during this century. Native Hawaiians may have known about Kauō before Americans and Europeans sailed their ships into the region in the early 19th century, the first reported sightings of the island were by Massachusetts whalers in the 1820s. The Nantucket Enquirer reported a sighting in 1825, here we probably find the first reference to the name Laysan in print. A United States government survey of Pacific Ocean geography in 1828 included the earlier whalers reports, john Briggs of New Bedford, who may have come across the island as early as 1822. Various publications name Capt. Stanyukovich of the Russian ship Moller as the discoverer of Laysan, although he mapped the island in 1828 and attempted to name it for his ship, he clearly was there after the New Englanders, at least. John Paty of the Manuokawai annexed Laysan to the Kingdom of Hawaiʻi. In 1859, Capt. Brooks of the ship Gambia traveled to the island, and in his ship log wrote that there was guano there, in 1890, the Kingdom of Hawaiʻi granted George D. Freeth and Charles N. Spencer permission to mine the guano on Laysan anyway, as long as they paid a royalty and this newfound attention to Laysan attracted scientists, and in the next decade, many of Laysans unique species were scientifically examined for the first time. The working conditions at the mines were grueling, but there seemed to be more guano than Capt. Brooks had thought. Around 100 short tons were extracted per day, in August 1900, the Japanese workers mutinied against the American management and refused to work, leading to violence because of the language barrier, there were two deaths and two injuries. Guano digging affected the ecosystem dramatically
10.
Basalt
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Basalt is a common extrusive igneous rock formed from the rapid cooling of basaltic lava exposed at or very near the surface of a planet or moon. Flood basalt describes the formation in a series of basalt flows. By definition, basalt is an igneous rock with generally 45-55% silica and less than 10% feldspathoid by volume. Basalt commonly features a very fine-grained or glassy matrix interspersed with visible mineral grains, the average density is 3.0 gm/cm3. Basalt is defined by its content and texture, and physical descriptions without mineralogical context may be unreliable in some circumstances. Basalt is usually grey to black in colour, but rapidly weathers to brown or rust-red due to oxidation of its mafic minerals into hematite, although usually characterized as dark, basaltic rocks exhibit a wide range of shading due to regional geochemical processes. Due to weathering or high concentrations of plagioclase, some basalts can be quite light-coloured and these phenocrysts usually are of olivine or a calcium-rich plagioclase, which have the highest melting temperatures of the typical minerals that can crystallize from the melt. Basalt with a texture is called vesicular basalt, when the bulk of the rock is mostly solid. Gabbro is often marketed commercially as black granite and these ultramafic volcanic rocks, with silica contents below 45% are usually classified as komatiites. Agricola applied basalt to the black rock of the Schloßberg at Stolpen. Tholeiitic basalt is relatively rich in silica and poor in sodium, included in this category are most basalts of the ocean floor, most large oceanic islands, and continental flood basalts such as the Columbia River Plateau. Basalt rocks are in some cases classified after their content in High-Ti and Low-Ti varieties. High-Ti and Low-Ti basalts have been distinguished in the Paraná and Etendeka traps and it has greater than 17% alumina and is intermediate in composition between tholeiite and alkali basalt, the relatively alumina-rich composition is based on rocks without phenocrysts of plagioclase. Alkali basalt is relatively poor in silica and rich in sodium and it is silica-undersaturated and may contain feldspathoids, alkali feldspar and phlogopite. Boninite is a form of basalt that is erupted generally in back-arc basins. Ocean island basalt Lunar basalt On Earth, most basalt magmas have formed by melting of the mantle. Basalt commonly erupts on Io, the third largest moon of Jupiter, and has formed on the Moon, Mars, Venus. The crustal portions of oceanic tectonic plates are composed predominantly of basalt, produced from upwelling mantle below, the mineralogy of basalt is characterized by a preponderance of calcic plagioclase feldspar and pyroxene
11.
Shield volcano
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A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They are named for their low profile, resembling a warriors shield lying on the ground and this is caused by the highly fluid lava they erupt, which travels farther than lava erupted from stratovolcanoes. This results in the accumulation of broad sheets of lava. The shape of shield volcanoes is due to the low viscosity of their mafic lava, Shield volcanoes are built by effusive eruptions, which flow out in all directions to create a shield like that of a warrior. Shield volcano itself is taken from the German term Schildvulkan, examples of pyroclastic shields include Billy Mitchell volcano in Papua New Guinea and the Purico Complex in Chile, an example of a felsic shield is the Big Obsidian Flow in Oregon. Active shield volcanoes experience near-continuous eruptive activity over long periods of time. Mount Everest, by comparison, is 8,848 m in height, the research has not yet been confirmed. Shield volcanoes feature a slope that gradually steepens with elevation before eventually flattening near the summit. In height they are typically about one twentieth their width, although the general form of a typical shield volcano varies little worldwide regional differences exist in their size and morphological characteristics. 4° and an average volume of 1.7 km3. Rift zones are a prevalent feature on shield volcanoes that is rare on other volcanic types, the large, decentralized shape of Hawaiian volcanoes as compared to their smaller, symmetrical Icelandic cousins can be attributed to rift eruptions. Fissure venting is common in Hawaiʻi, most Hawaiian eruptions begin with a wall of fire along a major fissure line before centralizing to a small number of points. These eruptions, the calmest of volcanic events, are characterized by the emission of highly fluid basaltic lavas with low gaseous content. These lavas travel a far greater distance than those of other types before solidifying, forming extremely wide. Low volumes of such lavas layered over long periods of time are what slowly constructs the characteristically low, central-vent eruptions, meanwhile, often take the form of large lava fountains, which can reach heights of hundreds of meters or more. If eruptive rates are enough, they may even form splatter-fed lava flows. Hawaiian eruptions are often extremely long lived, Puʻu ʻŌʻō, a cone of Kilauea, has been erupting continuously since 1983. These lava flows can be anywhere between 2 and 20 m thick, pāhoehoe flows, in contrast, move in more conventional sheets, or by the advancement of lava toes in snaking lava columns. Increasing viscosity on the part of the lava or shear stress on the part of local topography can morph a pāhoehoe flow into an aa one, although most shield volcanoes are by volume almost entirely Hawaiian and basaltic in origin, they are rarely exclusively so
12.
Volcano
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A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. Earths volcanoes occur because its crust is broken into 17 major, therefore, on Earth, volcanoes are generally found where tectonic plates are diverging or converging. This type of volcanism falls under the umbrella of plate hypothesis volcanism, Volcanism away from plate boundaries has also been explained as mantle plumes. These so-called hotspots, for example Hawaii, are postulated to arise from upwelling diapirs with magma from the boundary,3,000 km deep in the Earth. Volcanoes are usually not created where two plates slide past one another. Erupting volcanoes can pose hazards, not only in the immediate vicinity of the eruption. Historically, so-called volcanic winters have caused catastrophic famines, the word volcano is derived from the name of Vulcano, a volcanic island in the Aeolian Islands of Italy whose name in turn comes from Vulcan, the god of fire in Roman mythology. The study of volcanoes is called volcanology, sometimes spelled vulcanology, at the mid-oceanic ridges, two tectonic plates diverge from one another as new oceanic crust is formed by the cooling and solidifying of hot molten rock. Most divergent plate boundaries are at the bottom of the oceans, therefore, most volcanic activity is submarine, black smokers are evidence of this kind of volcanic activity. Where the mid-oceanic ridge is above sea-level, volcanic islands are formed, for example, subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. In this case, the plate subducts, or submerges under the continental plate forming a deep ocean trench just offshore. In a process called flux melting, water released from the subducting plate lowers the temperature of the overlying mantle wedge. This magma tends to be very viscous due to its high content, so it often does not reach the surface. When it does reach the surface, a volcano is formed, typical examples of this kind of volcano are Mount Etna and the volcanoes in the Pacific Ring of Fire. Because tectonic plates move across them, each volcano becomes dormant and is eventually re-formed as the plate advances over the postulated plume and this theory is currently under criticism, however. The most common perception of a volcano is of a mountain, spewing lava and poisonous gases from a crater at its summit, however. The features of volcanoes are more complicated and their structure. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have features such as massive plateaus
State of Hawaii
