Bobrof Island is one of the Andreanof Islands subgroup of the Aleutian Islands in southwestern Alaska, US. Bobrof Island is a small, uninhabited island about 9 miles north and west of Kanaga Island, 7 miles northeast of Cape Sudak on Tanaga Island. Bobrof Island is 2.6 miles long and 1.8 miles wide with an area of 3 square miles, consists of the 2,421-foot high Bobrof Volcano. The volcanic crater, or cone, has been dissected. Underwater deposits adjacent to the island's northeast flank suggest an immense debris-avalanche has taken place. Bobrof Volcano is an inactive stratovolcano. No recorded eruptions have taken place in its vicinity, it has been considered as Holocene age. Because of the inclusion of Alaska, the United States has the largest number of active volcanoes in the world, many of them geologically young. In Alaska, at least 50 volcanoes, including those in the Aleutian archipelago, have erupted in historical time. Alaska accounts for about 80% of the United States' volcanoes, excluding the seamounts in the area, about 8% of the world's volcanoes, most of these are located among the Aleutian Islands.
The Aleutian Islands arc forms the northern boundary of the Pacific Ring of Fire, where tectonic activity generates earthquakes and volcanic eruptions regularly. The volcano is thought to be of Holocene age. Though no historical eruptions have taken place at Bobrof, it has erupted at least once; this data can be confirmed through pyroclastic flow deposits containing andesite. Once these flows were studied, at a building intended for earthquake monitoring, they confirmed that Bobrof was prone to explosive activity. There are lava deposits on the mountain which suggest activity similar to shield eruptions. In collected samples, there are traces of basaltic dacite. No complete publications exist for Bobrof's definite geology, just those with facts and some information. |b=50|l=en|t=4001|zf=0.0|ms=sel_00dec|dw=17.701027675209602|dh=6.035539041852557|dt=gov.census.aff.domain.map. EnglishMapExtent|if=gif|cx=-170.20089635341083|cy=63.430295928031335|zl=8|pz=8|bo=318:317:316:314:313:323:319|bl=362:393:358:357:356:355:354|ft=350:349:335:389:388:332:331|fl=381:403:204:380:369:379:368|g=04000US02&-PANEL_ID=p_dt_geo_map&-_lang=en&-geo_id=100$10000US020160001001132&-CONTEXT=dt&-format=&-search_results=100$10000US020500001001047&-ds_name=DEC_2000_SF1_U Bobrof Island: Block 1132, Census Tract 1, Aleutians West Census Area, Alaska United States Census Bureau Bobrof Island Photos Photographs from Bobrof Island, July 2008
Buldir Island is a small island in the western Aleutian Islands of the U. S. state of Alaska. It lies midway between the Rat Islands in the East, it is the most westerly of the Aleutian Islands which formed as a result of volcanic activity in the late Quaternary or Recent times. The rocks from which the island formed are of two different ages with a considerable time gap; the rocks of the older dome are olivine basalts and the younger dome consists of hornblende basalts and basaltic andesites. That this island is younger than some of the neighboring islands is suggested by the fact that there are fewer species of flowering plant on this island. Buldir Island was first sighted on October 28, 1741 by Vitus Bering during his exploration of the region; the island is small, with an area of just 7.4482 square miles. It is 2.5 miles wide. There was no human population reported by the 2000 census; the two major volcanoes on the island are the Buldir Volcano, which forms most of the island, the East Cape Volcano, which forms the island's northeast section.
Buldir Volcano is the taller, reaching 2,152 feet in the highest point on the island. The coastlines along the island are tall steep cliffs; the island is home to 21 species of breeding seabirds, making it the most diverse seabird colony in the Northern Hemisphere. The island's colonies include crested auklets and least auklets, as well as puffins, storm petrels and other species, it is one of only four locations in the world where red-legged kittiwakes breed
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, gases to escape from a magma chamber below the surface. Earth's volcanoes occur because its crust is broken into 17 major, rigid tectonic plates that float on a hotter, softer layer in its mantle. Therefore, on Earth, volcanoes are found where tectonic plates are diverging or converging, most are found underwater. For example, a mid-oceanic ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can form where there is stretching and thinning of the crust's plates, e.g. in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande Rift in North America. This type of volcanism falls under the umbrella of "plate hypothesis" volcanism. Volcanism away from plate boundaries has been explained as mantle plumes; these so-called "hotspots", for example Hawaii, are postulated to arise from upwelling diapirs with magma from the core–mantle boundary, 3,000 km deep in the Earth.
Volcanoes are not created where two tectonic plates slide past one another. Erupting volcanoes can pose many hazards, not only in the immediate vicinity of the eruption. One such hazard is that volcanic ash can be a threat to aircraft, in particular those with jet engines where ash particles can be melted by the high operating temperature. Large eruptions can affect temperature as ash and droplets of sulfuric acid obscure the sun and cool the Earth's lower atmosphere. 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 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; because the crust is thin at these ridges due to the pull of the tectonic plates, the release of pressure leads to adiabatic expansion and the partial melting of the mantle, causing volcanism and creating new oceanic crust.
Most divergent plate boundaries are at the bottom of the oceans. Black smokers are evidence of this kind of volcanic activity. Where the mid-oceanic ridge is above sea-level, volcanic islands are formed. Subduction zones are places where two plates an oceanic plate and a continental plate, collide. In this case, the oceanic 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 melting temperature of the overlying mantle wedge, thus creating magma; this magma tends to be viscous because of its high silica content, so it does not attain the surface but cools and solidifies at depth. When it does reach the surface, however, a volcano is formed. Typical examples are the volcanoes in the Pacific Ring of Fire. Hotspots are volcanic areas believed to be formed by mantle plumes, which are hypothesized to be columns of hot material rising from the core-mantle boundary in a fixed space that causes large-volume melting.
Because tectonic plates move across them, each volcano becomes dormant and is re-formed as the plate advances over the postulated plume. The Hawaiian Islands are said to have been formed in such a manner; this theory, has been doubted. The most common perception of a volcano is of a conical mountain, spewing lava and poisonous gases from a crater at its summit; the features of volcanoes are much more complicated and their structure and behavior depends on a number of factors. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have landscape features such as massive plateaus. Vents that issue volcanic material and gases can develop anywhere on the landform and may give rise to smaller cones such as Puʻu ʻŌʻō on a flank of Hawaii's Kīlauea. Other types of volcano include cryovolcanoes on some moons of Jupiter and Neptune. Active mud volcanoes tend to involve temperatures much lower than those of igneous volcanoes except when the mud volcano is a vent of an igneous volcano.
Volcanic fissure vents are linear fractures through which lava emerges. Shield volcanoes, so named for their broad, shield-like profiles, are formed by the eruption of low-viscosity lava that can flow a great distance from a vent, they do not explode catastrophically. Since low-viscosity magma is low in silica, shield volcanoes are more common in oceanic than continental settings; the Hawaiian volcanic chain is a series of shield cones, they are common in Iceland, as well. Lava domes are built by slow eruptions of viscous lava, they are sometimes formed within the crater of a previous volcanic eruption, as in the case of Mount Saint Helen
An island or isle is any piece of sub-continental land, surrounded by water. Small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or a lake island may be called an eyot or ait, a small island off the coast may be called a holm. A grouping of geographically or geologically related islands is called an archipelago, such as the Philippines. An island may be described despite the presence of an artificial land bridge; some places may retain "island" in their names for historical reasons after being connected to a larger landmass by a land bridge or landfill, such as Coney Island and Coronado Island, though these are speaking, tied islands. Conversely, when a piece of land is separated from the mainland by a man-made canal, for example the Peloponnese by the Corinth Canal or Marble Hill in northern Manhattan during the time between the building of the United States Ship Canal and the filling-in of the Harlem River which surrounded the area, it is not considered an island.
There are two main types of islands in the sea: oceanic. There are artificial islands; the word island derives from Middle English iland, from Old English igland. However, the spelling of the word was modified in the 15th century because of a false etymology caused by an incorrect association with the etymologically unrelated Old French loanword isle, which itself comes from the Latin word insula. Old English ieg is a cognate of Swedish ö and German Aue, related to Latin aqua. Greenland is the world's largest island, with an area of over 2.1 million km2, while Australia, the world's smallest continent, has an area of 7.6 million km2, but there is no standard of size that distinguishes islands from continents, or from islets. There is a difference between continents in terms of geology. Continents are the largest landmass of a particular continental plate. By contrast, islands are either extensions of the oceanic crust, or belong to a continental plate containing a larger landmass. Continental islands are bodies of land.
Examples are Borneo, Sumatra, Sakhalin and Hainan off Asia. A special type of continental island is the microcontinental island, created when a continent is rifted. Examples are Madagascar and Socotra off Africa, New Caledonia, New Zealand, some of the Seychelles. Another subtype is an island or bar formed by deposition of tiny rocks where water current loses some of its carrying capacity; this includes: barrier islands, which are accumulations of sand deposited by sea currents on the continental shelves fluvial or alluvial islands formed in river deltas or midstream within large rivers. While some are transitory and may disappear if the volume or speed of the current changes, others are stable and long-lived. Islets are small islands. Oceanic islands are islands; 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 Paul Rocks in the Atlantic Ocean and Macquarie Island in the Pacific. One type of volcanic oceanic island is found in a volcanic island arc; these islands arise from volcanoes. Examples are the Aleutian Islands, the Mariana Islands, most of Tonga in the Pacific Ocean; the only examples in the Atlantic Ocean are some of the Lesser Antilles and the South Sandwich Islands. Another type of volcanic oceanic island occurs. There are two examples: Iceland, the world's second largest volcanic island, Jan Mayen. Both are in the Atlantic. A third type of volcanic oceanic island is formed over volcanic hotspots. A hotspot is more or less stationary relative to the moving tectonic plate above it, so a chain of islands results as the plate drifts. Over long periods of time, this type of island is "drowned" by isostatic adjustment and eroded, becoming a seamount. Plate movement across a hot-spot produces a line of islands oriented in the direction of the plate movement. An example is the Hawaiian Islands, from Hawaii to Kure, which continue beneath the sea surface in a more northerly direction as the Emperor Seamounts.
Another chain with similar orientation is the Tuamotu Archipelago. The southernmost chain is the Austral Islands, with its northerly trending part the atolls in the nation of Tuvalu. Tristan da Cunha is an example of a hotspot volcano in the Atlantic Ocean. Another hotspot in the Atlantic is the island of Surtsey, formed in 1963. An atoll is an island formed from a coral reef that has grown on an eroded and submerged volcanic island; the reef forms a new island. Atolls are ring-shaped with a central lagoon. Examples are the Line Islands
Hawadax Island is an island in the Rat Islands archipelago of the western Aleutian Islands in the U. S. state of Alaska. The island was known as Rat Island until May 2012 when it was renamed Hawadax Island, an Aleut name meaning "entry" and "welcome"; the island has a land area of no permanent population. It is within the Alaska Maritime National Wildlife Refuge, it is 3.1 miles in width. The former name is the English translation of the name given to the islands by Captain Fyodor Petrovich Litke in 1827 when he visited the Aleutian Islands on a voyage around the world; the Rat Islands are earthquake-prone as they are on the boundary of the Pacific and North American tectonic plates. In 1965, there was a major earthquake with the magnitude 8.7 in the Rat Islands. The island was infested with brown rats, which are considered a nuisance invasive species due to their negative impact on the population of ground-nesting wild birds; the rats arrived on the island before 1780 due to a Japanese shipwreck.
Since the rats had a devastating effect on local seabirds that have no natural defenses against the rats. Invasive rats are present on 16 other islands in the Aleutian chain. In 2007, the U. S. Fish and Wildlife Service, which manages the refuge, was formulating plans to eradicate the rats; the eradication plan is modelled on a successful one to eliminate the Arctic fox from various Aleutian islands, where they were deliberately introduced for breeding. In June 2009, the island was declared rat-free for the first time in 229 years, although the site will be continually monitored for another two years for confirmation. In the preceding autumn, helicopters dropped brodifacoum poison onto the island from buckets for a week, which eliminated the rat population. However, the associated nontarget mortality, i.e. the deaths of animals other than the rats, was significant. Some nontarget mortality was expected, but the actual quantity exceeded what was predicted; the Ornithological Council reported that more than 420 birds were killed as a result of the rat eradication program.
Forty-six bald eagles died. Of the 320 glaucous-winged gull carcasses collected, toxicology tests implicated brodifacoum in 24 of the 34 tested. Fifty-four carcasses of another 25 bird species were found; the report found that the lead contractor which the FWS used, Island Conservation, had dropped more poisonous bait than they had proposed, including bait, intended to be saved as a backup. The FWS asked the Ornithological Council to determine if Island Conservation had exceeded the limit of their poison quantities, but the council decided not to resolve any "legal questions"; as of 2011, the State of Alaska issued a Notice of Violation and FWS law enforcement is still investigating. Steve Delehanty, the manager of the Alaska Maritime National Wildlife Refuge said that, "It was a learning experience, we made mistakes together." However, he stated, "...if you do the math this was a rip-roaring conservation success." Campbell Island, New Zealand, the largest successful rat eradication. Rat Island Invasive Rat Eradication Project Environmental Assessment Rat Island: Block 1140, Census Tract 1, Aleutians West Census Area, Alaska United States Census Bureau THE RAT ISLAND RAT ERADICATION PROJECT: A CRITICAL EVALUATION OF NONTARGET MORTALITY.
PREPARED FOR ISLAND CONSERVATION THE NATURE CONSERVANCY and the U. S. FISH AND WILDLIFE SERVICE, ALASKA MARITIME NATIONAL WILDLIFE REFUGE. PREPARED BY THE ORNITHOLOGICAL COUNCIL. Final report issued December 2010. US Fish and Wildlife Service, Office of Law Enforcement, Report of Investigation #2009703127R001
Attu is the westernmost and largest island in the Near Islands group of the Aleutian Islands of Alaska, the westernmost point of land relative to Alaska. The island became uninhabited in 2010; the island was the site of the only World War II land battle fought on the continental United States, its battlefield area is a U. S. National Historic Landmark. Attu Station, a former Coast Guard LORAN station, is located at 52°51′N 173°11′E, making it one of the westernmost points of the United States relative to the rest of the country. However, since it is in the Eastern Hemisphere, being on the opposite side of the 180° longitude line as the contiguous 48 states, it can be considered one of the easternmost points of the country (a second Aleutian Island, Semisopochnoi Island at 179°46′E, is the easternmost location in the United States by this definition. In the chain of the Aleuts, the next island to the west of Attu are the Russian Commander Islands, 208 miles away. Attu is nearly 1,100 miles from the Alaskan mainland and 750 miles northeast of the northernmost of the Kurile Islands of Russia, as well as being 1,500 miles from Anchorage, 2,000 miles from Alaska's capital of Juneau, 4,845 miles from New York City.
Attu is about 20 by 35 miles in size with a land area of 344.7 square miles, making it #23 on the list of largest islands in the United States. The population in the 2010 census was 20 people, all at the Attu Station, though all inhabitants left the island in the year when the station closed, it is the largest uninhabited island in the United States. As of 1982, the only significant trees on the island were those planted by American soldiers at a chapel constructed after the 1943 battle when the Japanese occupation was over. Although Attu Island is the westernmost body of land east of the International Date Line, its time zone is the same as other western Aleutian Islands, UTC−10, which means that locations to the south-southeast have earlier clocks; the name Attu is a transliteration of the Aleut name of the island. It was called Saint Theodore by the explorer Aleksei Chirikov in 1742. Attu, being the nearest to Kamchatka, was the first of the Aleutian Islands exploited by Russian traders; the first population estimate by the Russians put at most 175 Aleuts on Attu.
However, the large number and size of archeological sites on Attu have led to estimates of 2,000–5,000 inhabitants during the centuries preceding European contact. Russians would stay several years on the island hunting sea otters clashing with the local Aleut population. After the initial wave of traders, Attu was overlooked by ships heading further east; the Aleuts were the primary inhabitants of the island prior to World War II. But, on June 7, 1942, six months after the Japanese attack on Pearl Harbor, the 301st Independent Infantry Battalion of the Japanese Northern Army landed on the island, without opposition, one day after landing on nearby Kiska. Earlier, American territorial authorities had evacuated about 880 Aleuts from villages elsewhere in the Aleutian Islands to civilian camps in the Alaska Panhandle, where about 75 of them died of various infectious diseases over two years. However, Attu Village had not yet been evacuated. At the time, Attu's population consisted of 45 native Aleuts and two white Americans, Charles Foster Jones, a radio technician from St. Paris and his wife Etta, a schoolteacher from Vineland, New Jersey.
The village consisted of several houses around Chichagof Harbor. The 42 Attu inhabitants who survived the Japanese invasion were taken to a prison camp near Otaru, Hokkaidō. Sixteen of them died. Mr. Jones, 63, was killed by the Japanese forces immediately after the invasion. Mrs. Jones, 63, was subsequently taken to the Bund Hotel in Yokohama, which housed Australian prisoners of war from the 1942 Battle of Rabaul in Papua New Guinea. Mrs. Jones and the Australian prisoners were held at the Yokohama Yacht Club from 1942 to 1944, at the Totsuka prisoner of war camp until their release in August 1945. Mrs. Jones died in December 1965 at age 86 in Florida. Before the Attu villagers were returned to the U. S. the American government stated publicly. According to Gen. Kiichiro Higuchi, the Commander of the Japanese Northern Army, the invasion of Kiska and Attu was part of a threefold objective: To break up any offensives against Japan by way of the Aleutians. To place a barrier between the U. S. and Russia in case Russia decided to join the war against Japan.
To make preparation for air bases for future offensive action. In late September 1942, the Japanese garrison on Attu was transferred to Kiska, Attu was left unoccupied, but American forces made no attempt to occupy Attu during this time. On October 29, 1942, the Japanese reestablished a base on Attu at Holtz Bay under the command of Lt. Col. Hiroshi Yanekawa; the garrison was about 500 troops, but through reinforcements, that number reached about 2,300 by March 10, 1943. No more reinforcements arrived after that time, owing to the efforts of the U. S. naval force under Rear Admiral Charles "Soc" McMorris, U. S. Navy submarines. McMorris had been assigned to interdict reinforcement convoys. After the sizable naval Battle of the Komandorski Islands, the Japanese abandoned their attempts to resupply its Aleutian garrisons by surface ships. From on, o