1.
Lava dome
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In volcanology, a lava dome or volcanic dome is a roughly circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. The geochemistry of lava domes can vary from basalt to rhyolite although most preserved domes tend to have high silica content, the characteristic dome shape is attributed to high viscosity that prevents the lava from flowing very far. This high viscosity can be obtained in two ways, by high levels of silica in the magma, or by degassing of fluid magma. Since viscous basaltic and andesitic domes weather fast and easily break apart by further input of fluid lava, most of the domes have high silica content. Existence of lava domes has been suggested for some domed structures on the Martian surface in the part of Arcadia Planitia. Lava domes evolve unpredictably, due to non-linear dynamics caused by crystallization, domes undergo various processes such as growth, collapse, solidification and erosion. Lava domes grow by endogenic dome growth or exogenic dome growth, the former implies dome interior expansion to accommodate new lava and the latter refers to superficial piling up of lava. It is the viscosity of the lava that prevents it from flowing far from the vent from which it extrudes. Domes may reach heights of several hundred meters, and can grow slowly and steadily for months, years, the sides of these structures are composed of unstable rock debris. Due to the intermittent buildup of gas pressure, erupting domes can often experience episodes of explosive eruption over time, if part of a lava dome collapses while it is still molten, it can produce pyroclastic flows, one of the most lethal forms of volcanic event. Other hazards associated with domes are the destruction of property, forest fires. Lava domes are one of the structural features of many stratovolcanoes worldwide. Lava domes are prone to unusually dangerous explosions since they contain rhyolitic silica-rich lava, characteristics of lava dome eruptions include shallow, long-period and hybrid seismicity, which is attributed to excess fluid pressures in the contributing vent chamber. Other characteristics of lava domes include their hemispherical shape, cycles of dome growth over long periods. The average rate of growth may be used as a rough indicator of magma supply. A cryptodome is a structure created by accumulation of viscous magma at a shallow depth. Coulées are lava domes that have experienced some flow away from their original position, the worlds largest known dacite flow is the Chao dacite dome complex, a huge coulée flow-dome between two volcanoes in northern Chile. This flow is over 14 kilometres long, has obvious flow features like pressure ridges, there is another prominent coulée flow on the flank of Llullaillaco volcano, in Argentina, and other examples in the Andes
2.
Summit
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A summit is a point on a surface that is higher in elevation than all points immediately adjacent to it. Mathematically, a summit is a maximum in elevation. The topographic terms acme, apex, peak, and zenith are synonymous, the UIAA definition is that a summit is independent if it has a prominence of 30 metres or more, it is a mountain if it has a prominence of at least 300 metres. This can be summarised as follows, A pyramidal peak is an exaggerated form produced by ice erosion of a mountain top, Summit may also refer to the highest point along a line, trail, or route. In many parts of the western United States, the term refers to the highest point along a road, highway. For example, the highest point along Interstate 80 in California is referred to as Donner Summit while the highest point on Interstate 5 is Siskiyou Mountain Summit, geoid Hill List of highest mountains Maxima and minima Nadir Summit accordance Peak finder
3.
Geographic coordinate system
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A geographic coordinate system is a coordinate system used in geography that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are chosen such that one of the numbers represents a vertical position. A common choice of coordinates is latitude, longitude and elevation, to specify a location on a two-dimensional map requires a map projection. The invention of a coordinate system is generally credited to Eratosthenes of Cyrene. Ptolemy credited him with the adoption of longitude and latitude. Ptolemys 2nd-century Geography used the prime meridian but measured latitude from the equator instead. Mathematical cartography resumed in Europe following Maximus Planudes recovery of Ptolemys text a little before 1300, in 1884, the United States hosted the International Meridian Conference, attended by representatives from twenty-five nations. Twenty-two of them agreed to adopt the longitude of the Royal Observatory in Greenwich, the Dominican Republic voted against the motion, while France and Brazil abstained. France adopted Greenwich Mean Time in place of local determinations by the Paris Observatory in 1911, the latitude of a point on Earths surface is the angle between the equatorial plane and the straight line that passes through that point and through the center of the Earth. Lines joining points of the same latitude trace circles on the surface of Earth called parallels, as they are parallel to the equator, the north pole is 90° N, the south pole is 90° S. The 0° parallel of latitude is designated the equator, the plane of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres, the longitude of a point on Earths surface is the angle east or west of a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses, which converge at the north and south poles, the prime meridian determines the proper Eastern and Western Hemispheres, although maps often divide these hemispheres further west in order to keep the Old World on a single side. The antipodal meridian of Greenwich is both 180°W and 180°E, the combination of these two components specifies the position of any location on the surface of Earth, without consideration of altitude or depth. The grid formed by lines of latitude and longitude is known as a graticule, the origin/zero point of this system is located in the Gulf of Guinea about 625 km south of Tema, Ghana. To completely specify a location of a feature on, in, or above Earth. Earth is not a sphere, but a shape approximating a biaxial ellipsoid. It is nearly spherical, but has an equatorial bulge making the radius at the equator about 0. 3% larger than the radius measured through the poles, the shorter axis approximately coincides with the axis of rotation
4.
Katmai National Park and Preserve
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Katmai National Park and Preserve is a United States National Park and Preserve in southern Alaska, notable for the Valley of Ten Thousand Smokes and for its Alaskan brown bears. The park and preserve covers 4,093,077 acres, most of this is a designated wilderness area in the national park where all hunting is banned, including over 3,922,000 acres of land. The park is named after Mount Katmai, its centerpiece stratovolcano, the park is located on the Alaska Peninsula, across from Kodiak Island, with headquarters in nearby King Salmon, about 290 miles southwest of Anchorage. The park includes as many as 18 individual volcanoes, seven of which have been active since 1900, following its designation, the monument was left undeveloped and largely unvisited until the 1950s. After a series of expansions, the present national park. Katmai occupies the Pacific Ocean side of the Alaska Peninsula, opposite Kodiak Island on the Shelikof Strait, the closest significant town to the park is King Salmon, where the parks headquarters is located, about 5 miles down the Naknek River from the park entrance. The Alaska Peninsula Highway connects Naknek Lake near the entrance to King Salmon, the road is not connected to the Alaska road system. Access to the interior is by boat on Naknek Lake. Another road runs from Brooks Camp to Three Forks, which overlooks the Valley of Ten Thousand Smokes, the 497-mile long coastline is deeply indented, running from the entrance to the Cook Inlet at Kamishak Bay south to Cape Kubugakli. The mountains run from southwest to northeast, about 15 miles inland, the park includes McNeil River State Game Sanctuary and Refuge on Kamishak Bay. The Alagnak River, designated a wild river, originates within the preserve at Kukaklek Lake, the Naknek River, which empties into Bristol Bay, originates within the park. The park adjoins Becharof National Wildlife Refuge to the south, of the park and preserves acres,3,922,529 acres are in the national park where all sport and subsistence hunting is prohibited. 418,548 acres are preserve lands, where sport and subsistence hunting are permitted. The most commonly hunted species in the preserve include grizzly bear, the granite Aleutian Range batholith has intruded through these rocks. The majority of the mountains in the park are of volcanic origin. The park has been altered by glaciation, both in the high lands where the mountains have been sculpted by glaciers, and in the lowlands where lakes have been excavated. Outwash plains and terminal moraines are also featured in the park, soil types vary from rock or volcanic ash of vary depth to deep, wet soils overlain with peat Although permafrost exists at higher elevations, it is not present in the lowlands. Two physiographic provinces cover the park, the Aleutian Range province is composed of the Shelikof Strait coastline, about 10 miles deep along the coast, the Aleutian Mountain zone, and the lake, or Hudsonian zone
5.
Alaska
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Alaska is a U. S. state located in the northwest extremity of North America. To the north are the Chukchi and Beaufort seas–the southern parts of the Arctic Ocean, the Pacific Ocean lies to the south and southwest. Alaska is the largest state in the United States by area, the 3rd least populous, approximately half of Alaskas residents live within the Anchorage metropolitan area. Alaskas economy is dominated by the fishing, natural gas, military bases and tourism are also a significant part of the economy. The United States purchased Alaska from the Russian Empire on March 30,1867, the area went through several administrative changes before becoming organized as a territory on May 11,1912. It was admitted as the 49th state of the U. S. on January 3,1959, the name Alaska was introduced in the Russian colonial period when it was used to refer to the peninsula. It was derived from an Aleut, or Unangam idiom, which refers to the mainland of Alaska. Literally, it means object to which the action of the sea is directed, Alaska is the northernmost and westernmost state in the United States and has the most easterly longitude in the United States because the Aleutian Islands extend into the Eastern Hemisphere. Alaska is the only non-contiguous U. S. state on continental North America and it is technically part of the continental U. S. but is sometimes not included in colloquial use, Alaska is not part of the contiguous U. S. often called the Lower 48. The capital city, Juneau, is situated on the mainland of the North American continent but is not connected by road to the rest of the North American highway system. Alaskas territorial waters touch Russias territorial waters in the Bering Strait, as the Russian Big Diomede Island, Alaska has a longer coastline than all the other U. S. states combined. Alaska is the largest state in the United States by total area at 663,268 square miles, over twice the size of Texas, Alaska is larger than all but 18 sovereign countries. Counting territorial waters, Alaska is larger than the area of the next three largest states, Texas, California, and Montana. It is also larger than the area of the 22 smallest U. S. states. Also referred to as the Panhandle or Inside Passage, this is the region of Alaska closest to the rest of the United States, as such, this was where most of the initial non-indigenous settlement occurred in the years following the Alaska Purchase. The region is dominated by the Alexander Archipelago as well as the Tongass National Forest and it contains the state capital Juneau, the former capital Sitka, and Ketchikan, at one time Alaskas largest city. The Alaska Marine Highway provides a vital transportation link throughout the area. The Interior is the largest region of Alaska, much of it is uninhabited wilderness, Fairbanks is the only large city in the region
6.
Mountain range
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A mountain range is a geographic area containing numerous geologically related mountains. A mountain system or system of ranges, sometimes is used to combine several geological features that are geographically related. Mountain ranges are usually segmented by highlands or mountain passes and valleys, individual mountains within the same mountain range do not necessarily have the same geologic structure or petrology. They may be a mix of different orogenic expressions and terranes, for example thrust sheets, uplifted blocks, fold mountains, most geologically young mountain ranges on the Earths land surface are associated with either the Pacific Ring of Fire or the Alpide Belt. The Andes is 7,000 kilometres long and is considered the worlds longest mountain system. The Alpide belt includes Indonesia and southeast Asia, through the Himalaya, the belt also includes other European and Asian mountain ranges. The Himalayas contain the highest mountains in the world, including Mount Everest, mountain ranges outside of these two systems include the Arctic Cordillera, the Urals, the Appalachians, the Scandinavian Mountains, the Altai Mountains and the Hijaz Mountains. If the definition of a range is stretched to include underwater mountains. The mountain systems of the earth are characterized by a tree structure, the sub-range relationship is often expressed as a parent-child relationship. For example, the White Mountains of New Hampshire and the Blue Ridge Mountains are sub-ranges of the Appalachian Mountains, equivalently, the Appalachians are the parent of the White Mountains and Blue Ridge Mountains, and the White Mountains and the Blue Ridge Mountains are children of the Appalachians. The position of mountains influences climate, such as rain or snow, when air masses move up and over mountains, the air cools producing orographic precipitation. As the air descends on the side, it warms again and is drier. Often, a shadow will affect the leeward side of a range. Mountain ranges are constantly subjected to forces which work to tear them down. Erosion is at work while the mountains are being uplifted and long after until the mountains are reduced to low hills, rivers are traditionally believed to be the principle erosive factor on mountain ranges, with their ability of bedrock incision and sediment transport. The rugged topography of a range is the product of erosion. The basins adjacent to a mountain range are filled with sediments which are buried and turned into sedimentary rock. The early Cenozoic uplift of the Rocky Mountains of Colorado provides an example and this mass of rock was removed as the range was actively undergoing uplift
7.
Aleutian Range
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The Aleutian Range is a major mountain range located in southwest Alaska, and it extends from Chakachamna Lake to Unimak Island, which is at the tip of the Alaska Peninsula. It includes all of the mountains of the peninsula, and what makes it so special is its number of active volcanoes. The mainland part of the range is about 600 miles long, however the official designation Aleutian Range includes only the mainland peaks and the peaks on Unimak Island. The range is almost entirely roadless wilderness, and Katmai National Park and Preserve, the core Aleutian Range can be divided into three mountain groups. Just to the north of the Aleutian Range are the Tordrillo Mountains, on July 12,2008, Mount Okmok erupted, and it continued to erupt for a month. A giant, rapidly moving ash and gas cloud shot up to a height of 15,240 m as a result of this eruption, Mount Kasatochi was home to the other eruption, which occurred on August 7 and 8. This eruption also sent up a gas cloud about 15,000 high, together, these two power volcanic eruptions deposited emissions of trace gases an aerosols into the atmosphere. These emissions formed a sulfate aerosol layer that totaled a transfer of 1.6 Tg of SO2 into the stratosphere, the 7.9 Mw Aleutian Islands earthquake occurred in June 2014 at an intermediate depth of 107 km. The quake was caused by normal faulting along the Aleutian Trench. List of earthquakes in Alaska U. S. Geological Survey Geographic Names Information System, Aleutian Range
8.
Topographic map
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Traditional definitions require a topographic map to show both natural and man-made features. A topographic map is published as a map series, made up of two or more map sheets that combine to form the whole map. A contour line is a line connecting places of equal elevation, however, in the vernacular and day to day world, the representation of relief is popularly held to define the genre, such that even small-scale maps showing relief are commonly called topographic. The study or discipline of topography is a broader field of study. Topographic maps are based on topographical surveys, performed at large scales, these surveys are called topographical in the old sense of topography, showing a variety of elevations and landforms. This is in contrast to older cadastral surveys, which primarily show property, the first multi-sheet topographic map series of an entire country, the Carte géométrique de la France, was completed in 1789. Topographic surveys were prepared by the military to assist in planning for battle, as such, elevation information was of vital importance. As they evolved, topographic map series became a resource in modern nations in planning infrastructure. Excluding borders, each sheet was 44 cm high and up to 66 cm wide, although the project eventually foundered, it left an indexing system that remains in use. TIGER was developed in the 1980s and used in the 1990, digital elevation models were also compiled, initially from topographic maps and stereographic interpretation of aerial photographs and then from satellite photography and radar data. Since all these were government projects funded with taxes and not classified for security reasons. Initial applications were mostly professionalized forms such as innovative surveying instruments, by the mid-1990s, increasingly user-friendly resources such as online mapping in two and three dimensions, integration of GPS with mobile phones and automotive navigation systems appeared. As of 2011, the future of standardized, centrally printed topographical maps is left somewhat in doubt, the various features shown on the map are represented by conventional signs or symbols. For example, colors can be used to indicate a classification of roads and these signs are usually explained in the margin of the map, or on a separately published characteristic sheet. Topographic maps are commonly called contour maps or topo maps. In the United States, where the national series is organized by a strict 7. 5-minute grid. Topographic maps conventionally show topography, or land contours, by means of contour lines, contour lines are curves that connect contiguous points of the same altitude. In other words, every point on the line of 100 m elevation is 100 m above mean sea level
9.
United States Geological Survey
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The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its resources. The organization has four science disciplines, concerning biology, geography, geology. The USGS is a research organization with no regulatory responsibility. The USGS is a bureau of the United States Department of the Interior, the USGS employs approximately 8,670 people and is headquartered in Reston, Virginia. The USGS also has major offices near Lakewood, Colorado, at the Denver Federal Center, the current motto of the USGS, in use since August 1997, is science for a changing world. The agencys previous slogan, adopted on the occasion of its anniversary, was Earth Science in the Public Service. Prompted by a report from the National Academy of Sciences, the USGS was created, by a last-minute amendment and it was charged with the classification of the public lands, and examination of the geological structure, mineral resources, and products of the national domain. This task was driven by the need to inventory the vast lands added to the United States by the Louisiana Purchase in 1803, the legislation also provided that the Hayden, Powell, and Wheeler surveys be discontinued as of June 30,1879. Clarence King, the first director of USGS, assembled the new organization from disparate regional survey agencies, after a short tenure, King was succeeded in the directors chair by John Wesley Powell. Administratively, it is divided into a Headquarters unit and six Regional Units, Other specific programs include, Earthquake Hazards Program monitors earthquake activity worldwide. The National Earthquake Information Center in Golden, Colorado on the campus of the Colorado School of Mines detects the location, the USGS also runs or supports several regional monitoring networks in the United States under the umbrella of the Advanced National Seismic System. The USGS informs authorities, emergency responders, the media, and it also maintains long-term archives of earthquake data for scientific and engineering research. It also conducts and supports research on long-term seismic hazards, USGS has released the UCERF California earthquake forecast. The USGS National Geomagnetism Program monitors the magnetic field at magnetic observatories and distributes magnetometer data in real time, the USGS operates the streamgaging network for the United States, with over 7400 streamgages. Real-time streamflow data are available online, since 1962, the Astrogeology Research Program has been involved in global, lunar, and planetary exploration and mapping. USGS operates a number of related programs, notably the National Streamflow Information Program. USGS Water data is available from their National Water Information System database
10.
Caldera
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A caldera is a large cauldron-like depression that forms following the evacuation of a magma chamber/reservoir. When large volumes of magma are erupted over a time period. The ground surface then collapses downward into the emptied magma chamber. Although sometimes described as a crater, the feature is actually a type of sinkhole, as it is formed through subsidence, only seven known caldera-forming collapses have occurred since the start of the 20th century, most recently at Bárðarbunga volcano in Iceland. The word comes from Spanish caldera, and this from Latin caldaria, in some texts the English term cauldron is also used. If enough magma is ejected, the chamber is unable to support the weight of the volcanic edifice above it. A roughly circular fracture, the fault, develops around the edge of the chamber. Ring fractures serve as feeders for fault intrusions which are known as ring dykes. Secondary volcanic vents may form above the ring fracture, as the magma chamber empties, the center of the volcano within the ring fracture begins to collapse. The collapse may occur as the result of a cataclysmic eruption. The total area that collapses may be hundreds or thousands of square kilometers, some calderas are known to host rich ore deposits. One of the worlds best-preserved mineralized calderas is the Sturgeon Lake Caldera in northwestern Ontario, Canada, if the magma is rich in silica, the caldera is often filled in with ignimbrite, tuff, rhyolite, and other igneous rocks. Silica-rich magma has a high viscosity, and therefore does not flow easily like basalt, as a result, gases tend to become trapped at high pressure within the magma. Further lava flows may be erupted, if volcanic activity continues, the center of the caldera may be uplifted in the form of a resurgent dome such as is seen at Cerro Galán, Lake Toba, Yellowstone, etc. by subsequent intrusion of magma. A silicic or rhyolitic caldera may erupt hundreds or even thousands of kilometers of material in a single event. Even small caldera-forming eruptions, such as Krakatoa in 1883 or Mount Pinatubo in 1991, may result in significant local destruction, large calderas may have even greater effects. When Yellowstone Caldera last erupted some 650,000 years ago, it released about 1,000 km3 of material, by comparison, when Mount St. Helens erupted in 1980, it released ~1.2 km3 of ejecta. The ecological effects of the eruption of a large caldera can be seen in the record of the Lake Toba eruption in Indonesia, more recently several geneticists, including Lynn Jorde and Henry Harpending have proposed that the human species was reduced to approximately five to ten thousand people
11.
Volcanic arc
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A volcanic arc is a chain of volcanoes formed above a subducting plate, positioned in an arc shape as seen from above. Offshore volcanoes form islands, resulting in an island arc. Generally, volcanic arcs result from the subduction of a tectonic plate under another tectonic plate. The oceanic plate is saturated with water, and volatiles such as water drastically lower the point of the mantle. As the oceanic plate is subducted, it is subjected to greater and greater pressures with increasing depth and this pressure squeezes water out of the plate and introduces it to the mantle. Here the mantle melts and forms magma at depth under the overriding plate, the magma ascends to form an arc of volcanoes parallel to the subduction zone. The Hawaiian Islands form a typical hotspot chain, the islands to the northwest are smaller and more lush than the recently created Hawaii island itself. Hotspot volcanoes are known as intra-plate volcanoes, and the islands they create are known as Volcanic Ocean Islands. Volcanic arcs do not generally such a simple age-pattern. There are two types of volcanic arcs, oceanic arcs form when oceanic crust subducts beneath other oceanic crust on an adjacent plate, continental arcs form when oceanic crust subducts beneath continental crust on an adjacent plate, creating an arc-shaped mountain belt. In some situations, a subduction zone may show both aspects along its length, as part of a plate subducts beneath a continent and part beneath adjacent oceanic crust. Volcanoes are present in almost any mountain belt, but this does not make it a volcanic arc, often there are isolated, but impressively huge volcanoes in a mountain belt. For instance, Vesuvius and the Etna volcanoes in Italy are part of separate, the active front of a volcanic arc is the belt where volcanism develops at a given time. Active fronts may move over time, changing their distance from the trench as well as their width. This loss of water is due to the destabilization of the mineral chlorite at approximately 40–60 km depth. On the subducting side of the arc is a deep and narrow oceanic trench. This trench is created by the pull of the relatively dense subducting plate pulling the leading edge of the plate downward. Multiple earthquakes occur along this boundary with the seismic hypocenters located at increasing depth under the island arc
12.
Volcanic belt
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A volcanic belt is a large volcanically active region. Other terms are used for areas of activity, such as volcanic fields. Volcanic belts are found above zones of high temperature where magma is created by partial melting of solid material in the Earths crust. These areas usually form along tectonic plate boundaries at depths of 10–50 km, the deeply deformed and eroded remnants of ancient volcanic belts are found in volcanically inactive regions such as the Canadian Shield. It contains over 150 volcanic belts that range from 600 to 1200 million years old and these are zones of variably metamorphosed mafic to ultramafic volcanic sequences with associated sedimentary rocks that form what are known as greenstone belts. They are thought to have formed at ancient oceanic spreading centers, the Abitibi greenstone belt in Ontario and Quebec, Canada is one of the worlds largest greenstone belts. Volcanic belts may be formed by multiple tectonic settings, an oceanic plate ordinarily slides underneath a continental plate, this often creates an orogenic zone with many volcanoes and earthquakes. In a sense, subduction zones are the opposite of divergent boundaries, areas where material rises up from the mantle, Volcanic belts may also be formed by hotspots, which is a location on the Earths surface that has experienced active volcanism for a long period of time. These volcanic belts are called volcanic chains, but more recently some geologists, such as Gillian Foulger view upper-mantle convection as a cause. This in turn has re-raised the antipodal pair impact hypothesis, the idea that pairs of opposite hot spots may result from the impact of a large meteor. Geologists have identified some 40-50 such hotspots around the globe, with Hawaii, Réunion, Yellowstone, Galápagos, and Iceland overlying the most currently active. An example of a volcanic belt is the Anahim Volcanic Belt in British Columbia, Canada. Most hotspot volcanoes are basaltic because they erupt through oceanic lithosphere, as a result, they are less explosive than subduction zone volcanoes, which have high water contents. Where hotspots occur under continental crust, basaltic magma is trapped in the less dense continental crust and these rhyolites can be quite hot and form violent eruptions, despite their low water content. For example, the Yellowstone Caldera was formed by some of the most powerful explosions in geologic history. Andean Volcanic Belt Garibaldi Volcanic Belt Taupo Volcanic Zone Plate tectonics
13.
Aleutian Arc
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The Aleutian Arc is a large volcanic arc in the U. S. state of Alaska. It consists of a number of active and dormant volcanoes that have formed as a result of subduction along the Aleutian Trench, the Aleutian Arc reflects subduction of the Pacific Plate beneath the North American Plate. It extends 3,000 km from the Kamchatka Peninsula in the west to the Gulf of Alaska in the east, unimak Pass at the southwestern end of the Alaska Peninsula marks the eastward transition from an intra-oceanic in the west to a continental arc in the east. Due to the geometry of the trench, the relative velocity vector changes from almost trench-normal in the Gulf of Alaska to almost trench-parallel in the west. Along the oceanic part of the zone, convergence varies from 6.3 cm per year to the north-northwest in the east to 7.4 cm per year towards the northwest in the west. Volcanoes within the arc include, Geoprisms. org, Aleutian Arc
14.
Types of volcanic eruptions
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Several types of volcanic eruptions—during which lava, tephra, and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed, some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series. There are three different types of eruptions, the most well-observed are magmatic eruptions, which involve the decompression of gas within magma that propels it forward. Phreatomagmatic eruptions are another type of eruption, driven by the compression of gas within magma. Within these wide-defining eruptive types are several subtypes, the weakest are Hawaiian and submarine, then Strombolian, followed by Vulcanian and Surtseyan. The stronger eruptive types are Pelean eruptions, followed by Plinian eruptions, subglacial and phreatic eruptions are defined by their eruptive mechanism, and vary in strength. An important measure of strength is Volcanic Explosivity Index, an order of magnitude scale ranging from 0 to 8 that often correlates to eruptive types. Explosive eruptions are characterized by gas-driven explosions that propels magma and tephra, effusive eruptions, meanwhile, are characterized by the outpouring of lava without significant explosive eruption. Volcanic eruptions vary widely in strength, on the one extreme there are effusive Hawaiian eruptions, which are characterized by lava fountains and fluid lava flows, which are typically not very dangerous. On the other extreme, Plinian eruptions are large, violent, volcanoes are not bound to one eruptive style, and frequently display many different types, both passive and explosive, even the span of a single eruptive cycle. Volcanoes do not always erupt vertically from a crater near their peak. Some volcanoes exhibit lateral and fissure eruptions, notably, many Hawaiian eruptions start from rift zones, and some of the strongest Surtseyan eruptions develop along fracture zones. Scientists believed that pulses of magma mixed together in the chamber before climbing upward—a process estimated to several thousands of years. But Columbia University volcanologists found that the eruption of Costa Rica’s Irazú Volcano in 1963 was likely triggered by magma that took a route from the mantle over just a few months. The volcanic explosivity index is a scale, from 0 to 8 and it is used by the Smithsonian Institutions Global Volcanism Program in assessing the impact of historic and prehistoric lava flows. It operates in a way similar to the Richter scale for earthquakes, the vast majority of volcanic eruptions are of VEIs between 0 and 2. Volcanic eruptions by VEI index Magmatic eruptions produce juvenile clasts during explosive decompression from gas release, Hawaiian eruptions are a type of volcanic eruption, named after the Hawaiian volcanoes with which this eruptive type is hallmark. Hawaiian eruptions are the calmest types of events, characterized by the effusive eruption of very fluid basalt-type lavas with low gaseous content
15.
Latin
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Latin is a classical language belonging to the Italic branch of the Indo-European languages. The Latin alphabet is derived from the Etruscan and Greek alphabets, Latin was originally spoken in Latium, in the Italian Peninsula. Through the power of the Roman Republic, it became the dominant language, Vulgar Latin developed into the Romance languages, such as Italian, Portuguese, Spanish, French, and Romanian. Latin, Italian and French have contributed many words to the English language, Latin and Ancient Greek roots are used in theology, biology, and medicine. By the late Roman Republic, Old Latin had been standardised into Classical Latin, Vulgar Latin was the colloquial form spoken during the same time and attested in inscriptions and the works of comic playwrights like Plautus and Terence. Late Latin is the language from the 3rd century. Later, Early Modern Latin and Modern Latin evolved, Latin was used as the language of international communication, scholarship, and science until well into the 18th century, when it began to be supplanted by vernaculars. Ecclesiastical Latin remains the language of the Holy See and the Roman Rite of the Catholic Church. Today, many students, scholars and members of the Catholic clergy speak Latin fluently and it is taught in primary, secondary and postsecondary educational institutions around the world. The language has been passed down through various forms, some inscriptions have been published in an internationally agreed, monumental, multivolume series, the Corpus Inscriptionum Latinarum. Authors and publishers vary, but the format is about the same, volumes detailing inscriptions with a critical apparatus stating the provenance, the reading and interpretation of these inscriptions is the subject matter of the field of epigraphy. The works of several hundred ancient authors who wrote in Latin have survived in whole or in part and they are in part the subject matter of the field of classics. The Cat in the Hat, and a book of fairy tales, additional resources include phrasebooks and resources for rendering everyday phrases and concepts into Latin, such as Meissners Latin Phrasebook. The Latin influence in English has been significant at all stages of its insular development. From the 16th to the 18th centuries, English writers cobbled together huge numbers of new words from Latin and Greek words, dubbed inkhorn terms, as if they had spilled from a pot of ink. Many of these words were used once by the author and then forgotten, many of the most common polysyllabic English words are of Latin origin through the medium of Old French. Romance words make respectively 59%, 20% and 14% of English, German and those figures can rise dramatically when only non-compound and non-derived words are included. Accordingly, Romance words make roughly 35% of the vocabulary of Dutch, Roman engineering had the same effect on scientific terminology as a whole
16.
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
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Alaska Peninsula
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The Alaska Peninsula is a peninsula extending about 800 km to the southwest from the mainland of Alaska and ending in the Aleutian Islands. The peninsula separates the Pacific Ocean from Bristol Bay, an arm of the Bering Sea, the Lake and Peninsula borough, the Alaskan equivalent of a county, is named after the peninsula. The Aleutian Range is an active volcanic mountain range which runs along the entire length of the Peninsula. The northern and southern shores are likewise quite different, the northern Bristol Bay coastal side is generally turbid and muddy, experiences tidal extremes, and is relatively shallow, the Pacific side has relatively small tidal activity and is deep and clear. All of the Peninsula is organized as a part of four adjacent boroughs, the Aleutians East Borough, Bristol Bay Borough, Kodiak Island Borough, the Lake and Peninsula Borough includes most of the peninsulas territory. Average annual precipitation ranges from 24 to 65 in, coastal areas are subject to intense storms, wind, and rain. Winter temperatures average between −11°C and 1°C, and in summer between 6°C and 15°, frosts can occur any day of the year at higher elevations. The climate can be compared to that of the Aleutian Islands, Iceland, the Alaska Peninsula is home to some of the largest populations of native and undisturbed wildlife in the United States. Besides the famous McNeil River and Katmai Alaskan brown bear populations, large herds of caribou, moose, wolves and these salmon, after returning from their short life at sea, swim into the lakes and their contributing streams to spawn. Their offspring, or fry, overwinter in the deep and food-abundant depths of these lakes until their migration to the sea in one or two years, exceptionally large seabird colonies exist along the coast. Besides the communities on the coast, the Alaska Peninsula also is home to several villages, Cold Bay, King Cove, Perryville, Chignik, Chignik Lake, Chignik Lagoon. Each is primarily inhabited by Alaska Natives and each, likewise, is dependent on the fishing industry for sustenance. The village of Sand Point should be included here, despite its location on Popof Island, ugashik Area website Lake & Peninsula Borough Lake and Peninsula School District Alaska Peninsula Trek Trawl survey of shrimp and forage fish in Alaskas Westward region,2006 / by David R. Jackson. Hosted by Alaska State Publications Program
18.
Anchorage, Alaska
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Anchorage is a unified home rule municipality in the U. S. state of Alaska. All together, the Anchorage metropolitan area, which combines Anchorage with the neighboring Matanuska-Susitna Borough, had a population of 401,635 in 2016. Anchorage is located in the portion of Alaska at the terminus of the Cook Inlet on a peninsula formed by the Knik Arm to the north. The city limits span 1,961.1 square miles encompass the urban core. Due to its location on the globe, being almost equidistant from New York City, Tokyo, Anchorage has been named an All-America City four times, in 1956,1965, 1984–85, and 2002, by the National Civic League. It has also named by Kiplinger as the most tax-friendly city in the United States. Russian presence in south central Alaska was well established in the 19th century, in 1867, U. S. Secretary of State William H. Seward brokered a deal to purchase Alaska from Imperial Russia for $7.2 million. His political rivals lampooned the deal as Sewards folly, Sewards icebox, by 1888, gold was discovered along Turnagain Arm. Alaska became a United States territory in 1912, Anchorage, unlike every other large town in Alaska south of the Brooks Range, was neither a fishing nor mining camp. The area surrounding Anchorage lacks significant economic metal minerals, a number of Denaina settlements existed along Knik Arm for years. By 1911 the families of J. D. Bud Whitney, jack Brown, and his bride, Nellie, in 1912 to have lived in the Ship Creek valley in the 1910s prior to the large influx of settlers. The city grew from its choice as the site, in 1914, under the direction of Frederick Mears. The area near the mouth of Ship Creek, where the headquarters was located. A town site was mapped out on higher ground to the south of the tent city, greatly noted in the years since for its order and rigidity compared with other Alaska town sites. In 1915, territorial governor John Franklin Alexander Strong encouraged residents to change the name to one that had more significance. In the summer of year, residents held a vote to change the citys name. However, the government ultimately declined to change the citys name. Anchorage was incorporated on November 23,1920, construction of the Alaska Railroad continued until its completion in 1923
19.
Magma
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Besides molten rock, magma may also contain suspended crystals, dissolved gas and sometimes gas bubbles. Magma often collects in magma chambers that may feed a volcano or solidify underground to form an intrusion, magma is capable of intruding into adjacent rocks, extrusion onto the surface as lava, and explosive ejection as tephra to form pyroclastic rock. Magma is a complex high-temperature fluid substance, temperatures of most magmas are in the range 700 °C to 1300 °C, but very rare carbonatite magmas may be as cool as 600 °C, and komatiite magmas may have been as hot as 1600 °C. Environments of magma formation and compositions are commonly correlated, environments include subduction zones, continental rift zones, mid-ocean ridges and hotspots. Despite being found in such locales, the bulk of the Earths crust. Except for the outer core, most of the Earth takes the form of a rheid. Magma, as liquid, preferentially forms in high temperature, low pressure environments within several kilometers of the Earths surface, magma compositions may evolve after formation by fractional crystallization, contamination, and magma mixing. By definition rock formed of solidified magma is called igneous rock, melting of solid rocks to form magma is controlled by three physical parameters, temperature, pressure, and composition. Mechanisms are discussed in the entry for igneous rock, as a rock melts, its volume changes. When enough rock is melted, the small globules of melt link up, under pressure within the earth, as little as a fraction of a percent partial melting may be sufficient to cause melt to be squeezed from its source. The degree of melting is critical for determining what type of magma is produced. The degree of partial melting required to form a melt can be estimated by considering the relative enrichment of incompatible elements versus compatible elements, incompatible elements commonly include potassium, barium, cesium, and rubidium. Rock types produced by small degrees of melting in the Earths mantle are typically alkaline. Typically, primitive melts of this composition form lamprophyre, lamproite, kimberlite and sometimes nepheline-bearing mafic rocks such as alkali basalts, pegmatite may be produced by low degrees of partial melting of the crust. Some granite-composition magmas are eutectic melts, and they may be produced by low to high degrees of melting of the crust. At high degrees of melting of the crust, granitoids such as tonalite, granodiorite and monzonite can be produced. Being only the time in recorded history that magma had been reached, IDDP decided to invest in the hole. A cemented steel case was constructed in the hole with a perforation at the close to the magma
20.
1980 eruption of Mount St. Helens
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On May 18,1980, a major volcanic eruption occurred at Mount St. Helens, a volcano located in Skamania County, in the state of Washington, United States. The eruption was the significant volcanic eruption to occur in the contiguous 48 U. S. states since the 1915 eruption of Lassen Peak in California. However, it has often declared as the most disastrous volcanic eruption in United States history. An earthquake at 8,32,17 a. m. PDT on Sunday, May 18,1980, caused the entire weakened north face to slide away, creating the largest landslide ever recorded. An eruption column rose 80,000 feet into the atmosphere, at the same time, snow, ice and several entire glaciers on the volcano melted, forming a series of large lahars that reached as far as the Columbia River, nearly 50 miles to the southwest. Less severe outbursts continued into the day, only to be followed by other large. Approximately fifty-seven people were killed directly, including innkeeper Harry R. Truman, photographer Reid Blackburn and geologist David A. Johnston. Hundreds of square miles were reduced to wasteland, causing over a billion U. S. dollars in damage, thousands of animals were killed. At the time of the eruption, the summit of the volcano was owned by the Burlington Northern Railroad, the area was later preserved, as it was, in the Mount St. Helens National Volcanic Monument. Mount St. Helens remained dormant from its last period of activity in the 1840s and 1850s until March 1980, several small earthquakes, apparently beginning on March 15, indicated that magma may have begun moving below the volcano. Then on March 20, at 3,45 p. m. Pacific Standard Time, a total of 174 shocks of magnitude 2.6 or greater were recorded during those two days. Initially there was no sign of eruption, but small earthquake-induced avalanches of snow. At 12,36 p. m. on March 27, phreatic eruptions ejected and smashed rock from within the old crater, excavating a new crater 250 feet wide. By this date a 16, 000-foot long eastward-trending fracture system had developed across the summit area. This was followed by more earthquake swarms and a series of explosions that sent ash 10,000 to 11,000 feet above their vent. Most of this ash fell between 3 and 12 miles from its vent, but some was carried 150 miles south to Bend, Oregon, or 285 miles east to Spokane, a second, new crater and a blue flame were observed on March 29. The flame was visibly emitted from both craters and was created by burning gases. Static electricity generated from ash clouds rolling down the volcano sent out lightning bolts that were up to 2 miles long
21.
Plinian eruption
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Plinian eruptions, also known as Vesuvian eruptions, are volcanic eruptions marked by their similarity to the eruption of Mount Vesuvius in 79 AD. The eruption was described in a written by Pliny the Younger, it killed his uncle. Plinian eruptions are marked by columns of gas and volcanic ash extending high into the stratosphere, the key characteristics are ejection of large amount of pumice and very powerful continuous gas blast eruptions. According to the Volcanic Explosivity Index, Plinian eruptions have a VEI of 4,5 or 6, short eruptions can end in less than a day, but longer events can take several days to months. The longer eruptions begin with production of clouds of volcanic ash, the amount of magma erupted can be so large that it depletes the magma chamber below, causing the top of the volcano to collapse, resulting in a caldera. Fine ash can deposit over large areas, Plinian eruptions are often accompanied by loud noises, such as those generated by Krakatoa. The lava is usually rhyolitic and rich in silicates, basaltic lavas are unusual for Plinian eruptions, the most recent basaltic example is the 1886 eruption of Mount Tarawera on New Zealands North Island. Pliny the Younger provided an account of his death, and suggested that he collapsed and died through inhaling poisonous gases emitted from the volcano. His body was interred under the ashes of the Vesuvius with no apparent injuries on 26 August, after the plume had dispersed. The June 2009 eruption of Sarychev Peak in Russia, the 1991 Mount Pinatubo eruption in Zambales of Central Luzon, Philippines. The 1980 eruption of Mount St. Helens in Washington, United States, the 1912 eruption of Novarupta in Alaska, United States. The 1886 eruption of Mount Tarawera in New Zealand, the 1883 eruption of Krakatoa in Sunda Strait, Indonesia. The 1815 eruption of Mount Tambora in the island of Sumbawa, the 1783 eruptions of Lakagígar in Iceland. The 1667 and 1739 eruptions of Mount Tarumae in Hokkaido, Japan, the A. D.180 Lake Taupo eruption in New Zealand. The A. D.79 eruption of Mount Vesuvius in Campania and it was the prototypical Plinian eruption. The 400s BC eruption of the Bridge River Vent in British Columbia, the 1645 BC eruption of Santorini in the south Aegean Sea, Greece. The 4860 BC eruption forming Crater Lake in Oregon, United States, the Long Valley Caldera eruption in Eastern California of United States, which happened over 760,000 years ago. According to the Volcanic Explosivity Index, a VEI of 6 to 8 is classified as Ultra Plinian, Eruptions of this type are defined by ash plumes over 25 km high and a volume of erupted material 10 km3 to 1,000 km3 in size
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Rhyolite
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Rhyolite is an igneous, volcanic rock, of felsic composition. It may have any texture from glassy to aphanitic to porphyritic, the mineral assemblage is usually quartz, sanidine and plagioclase. Biotite and hornblende are common accessory minerals and it is the extrusive equivalent to granite. Rhyolite can be considered as the equivalent to the plutonic granite rock. Due to their content of silica and low iron and magnesium contents, rhyolite melts are highly polymerized. They also occur as breccias or in volcanic plugs and dikes, rhyolites that cool too quickly to grow crystals form a natural glass or vitrophyre, also called obsidian. Slower cooling forms microscopic crystals in the lava and results in such as flow foliations, spherulitic, nodular. Some rhyolite is highly vesicular pumice, many eruptions of rhyolite are highly explosive and the deposits may consist of fallout tephra/tuff or of ignimbrites. Eruptions of rhyolite are relatively rare compared to eruptions of less felsic lavas, etsch Valley Vulcanite Group near Bolzano and the surrounding area Gréixer rhyolitic complex at Moixeró range Vosges Iceland, all active and extinct central volcanoes, e. g. g. Wichita Mountains within the Southern Oklahoma Aulacogen St, in North American pre-historic times, rhyolite was quarried extensively in eastern Pennsylvania in the United States. Among the leading quarries was the Carbaugh Run Rhyolite Quarry Site in Adams County, comendite List of rock types Pantellerite Thunderegg University of North Dakota description of rhyolite Information from rocks-rock. com
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Dacite
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Dacite is an igneous, volcanic rock. It has an aphanitic to porphyritic texture and is intermediate in composition between andesite and rhyolite, the word dacite comes from Dacia, a province of the Roman Empire which lay between the Danube River and Carpathian Mountains where the rock was first described. Dacite consists mostly of feldspar with biotite, hornblende. It has quartz as rounded, corroded phenocrysts, or as an element of the ground-mass, the relative proportions of feldspars and quartz in dacite, and in many other volcanic rocks, are illustrated in the QAPF diagram. The TAS classification, based on silica and alkali contents, puts dacite in the O3 sector, the plagioclase ranges from oligoclase to andesine and labradorite. Sanidine occurs, although in small proportions, in some dacites, the groundmass of these rocks is composed of plagioclase and quartz. In the hand specimen many of the hornblende and biotite dacites are grey or pale brown and yellow rocks with white feldspars, other dacites, especially pyroxene bearing dacites, are darker colored. In thin section, dacites may have an aphanitic to porphyritic texture, porphyritic dacites contain blocky highly zoned plagioclase phenocrysts and/or rounded corroded quartz phenocrysts. Subhedral hornblende and elongated biotite grains are present, sanidine phenocrysts and augite are found in some samples. Dacite usually forms as a rock such as a dike or sill. Examples of this type of dacite outcrop are found in northwestern Montana, nevertheless, because of the moderate silica content, dacitic magma is quite viscous and therefore prone to explosive eruption. A notorious example of this is Mount St. Helens in which dacite domes formed from previous eruptions, pyroclastic flows may also be of dacitic composition as is the case with the Fish Canyon Tuff of La Garita Caldera. Dacitic magma is formed by the subduction of oceanic crust under a thick felsic continental plate. Oceanic crust is hydrothermally altered causing addition of quartz and sodium, as the young, hot oceanic plate is subducted under continental crust, the subducted slab partially melts and interacts with the upper mantle through convection and dehydration reactions. The process of subduction creates metamorphism in the subducting slab, when this slab reaches the mantle and initiates the dehydration reactions, minerals such as talc, serpentine, mica and amphiboles break down generating a more sodic melt. The magma then continues to migrate upwards causing differentiation and becomes even more sodic and silicic as it rises, once at the cold surface, the sodium rich magma crystallizes plagioclase, quartz and hornblende. Accessory minerals like pyroxenes provide insight to the history of the magma, the formation of dacite provides a great deal of information about the connection between oceanic crust and continental crust. It provides a model for the generation of felsic, buoyant, perennial rock from a mafic, dense, the process by which dacite forms has been used to explain the generation of continental crust during the Archean eon
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Andesite
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For the extinct cephalopod genus, see Andesites. Andesite is an igneous, volcanic rock, of intermediate composition. In a general sense, it is the type between basalt and dacite, and ranges from 57 to 63% silicon dioxide as illustrated in TAS diagrams. The mineral assemblage is dominated by plagioclase plus pyroxene or hornblende. Magnetite, zircon, apatite, ilmenite, biotite, and garnet are common accessory minerals, alkali feldspar may be present in minor amounts. The quartz-feldspar abundances in andesite and other rocks are illustrated in QAPF diagrams. Classification of andesites may be refined according to the most abundant phenocryst, example, hornblende-phyric andesite, if hornblende is the principal accessory mineral. Andesite can be considered as the equivalent of plutonic diorite. Characteristic of subduction zones, andesite represents the dominant rock type in island arcs, the average composition of the continental crust is andesitic. Along with basalts they are a component of the Martian crust. The name andesite is derived from the Andes mountain range, magmatism in island arc regions comes from the interplay of the subducting plate and the mantle wedge, the wedge-shaped region between the subducting and overriding plates. During subduction, the oceanic crust is submitted to increasing pressure and temperature. Hydrous minerals such as amphibole, zeolites, chlorite etc. dehydrate as they change to more stable, anhydrous forms, releasing water, fluxing water into the wedge lowers the solidus of the mantle material and causes partial melting. Due to the density of the partially molten material, it rises through the wedge until it reaches the lower boundary of the overriding plate. Basalt thus formed can contribute to the formation of andesite through fractional crystallization, partial melting of crust, or magma mixing, andesite is typically formed at convergent plate margins but may occur in other tectonic settings. Intermediate volcanic rocks are created via several processes, Fractional crystallization of a mafic parent magma and this removal can take place in a variety of ways, but most commonly this occurs by crystal settling. The first minerals to crystallize and be removed from a parent are olivines and amphiboles. These mafic minerals settle out of the magma, forming mafic cumulates, there is geophysical evidence from several arcs that large layers of mafic cumulates lie at the base of the crust
25.
Pyroclastic fall
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A pyroclastic fall is a uniform deposit of material which has been ejected from a volcanic eruption or plume such as an ash fall or tuff. They exhibit mantle bedding—the deposits directly overlie pre-existing topography and maintain a uniform thickness over relatively short distances, sorting by size is more pronounced than pyroclastic surge or pyroclastic flows. Early settling of crystals and lithic fragments near an eruptive vent, the St Vincent eruption in 1902 ejected a large eruption column which when settled near the vent contained 73% crystals, and ash deposited in Jamaica 1,600 km away consisted entirely of glass dust. The distribution of pyroclastic ash depends largely on the direction of wind at intermediate, the general trend of pyroclastic dispersal is shown using isopachs and show the dispersal as elongated with wind direction. The Krakatoa eruption of 1883 produced a column which rose to more than 50 km. An ash flow from this explosion was recognised 2,500 km west of the volcano, the total area of recognisable pyroclastic fall was greater than 800,000 km². The pyroclastic ash encircled the globe in 13.5 days, the ash remained in the upper atmosphere and produced brilliant sunsets for many years, lowered the global temperature by 0.5 °C for at least five years. This is commonly known as an inversion of the magma chamber, the 79 AD eruption of Mount Vesuvius produced the Pompeii Pumice which is an example of lateral and vertical variations. The deposit is well sorted with density and size of pumice, the bottom layer of the pumice is white felsic rich pumice with a darker grey mafic pumice overlying it. These changes represent the increasing vigour of the eruption, the mafic upper part of the deposit reflects the increasing depth of the origin or compositionally zoned magma chamber. This unit represents an inversion of the chamber as progressively deeper materials from the chamber were tapped as the eruption progressed. Pyroclastic flow Pyroclastic rock Pyroclastic surge
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Tuff
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Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is compacted into a rock in a process called consolidation. Tuff is sometimes called tufa, particularly used as construction material. Rock that contains greater than 50% tuff is considered tuffaceous, Tuff is a relatively soft rock, so it has been used for construction since ancient times. Since it is common in Italy the Romans used it often for construction, the Rapa Nui people used it to make most of the moai statues in Easter Island. Tuff can be classified as either sedimentary or igneous rocks and they are usually studied in the context of igneous petrology, although they are sometimes described using sedimentological terms. The material that is expelled in a volcanic eruption can be classified into three types, Volcanic gases, a mixture mostly of water vapour, carbon dioxide. Lava, the name of magma when it emerges and flows over the surface, and tephra, chunks of solid material of all shapes and sizes ejected and thrown through the air. Tephra is made when magma inside the volcano is blown apart by the expansion of hot volcanic gases. It is common for magma to explode as the gas dissolved in it comes out of solution as the pressure decreases when it flows to the surface and these violent explosions produce solid chunks of material that can then fly from the volcano. When these chunks are smaller than 2 mm in diameter they are called volcanic ash and it is made of small, slaggy pieces of lava and rock that have been tossed into the air by outbursts of steam and other gases. Among the loose beds of ash that cover the slopes of many volcanoes, in addition to true ashes of the kind described above, there are lumps of the old lavas and tuffs forming the walls of the crater, etc. In some great volcanic explosions nothing but materials of the kind were emitted. The ashes vary in size from large blocks twenty feet or more in diameter to the minutest impalpable dust, the large masses are called volcanic bombs, they have mostly a rounded, elliptical or pear-shaped form owing to rotation in the air before they solidified. Many of them have ribbed or nodular surfaces, and sometimes they have a crust intersected by many cracks like the surface of a loaf of bread, any ash in which they are very abundant is called an agglomerate. But many volcanoes stand near the sea, and the ashes cast out by them are mingled with the sediments that are gathering at the bottom of the waters, in this way ashy muds or sands or even in some cases ashy limestones are being formed. As a matter of fact most of the found in the older formations contain admixtures of clay, sand, and sometimes fossil shells. The showers of ashes often follow one another after longer or shorter intervals, the coarsest materials or agglomerates show this least distinctly, in the fine beds it is often developed in great perfection
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Pyroclastic flow
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A pyroclastic flow is a fast-moving current of hot gas and volcanic matter, which reaches speeds moving away from a volcano of up to 700 km/h. The gases can reach temperatures of about 1,000 °C, Pyroclastic flows normally touch the ground and hurtle downhill, or spread laterally under gravity. Their speed depends upon the density of the current, the output rate. They are a common and devastating result of explosive eruptions. The word pyroclast is derived from the Greek πῦρ, meaning fire, a name for some pyroclastic flows is nuée ardente, this was first used to describe the disastrous 1902 eruption of Mount Pelée on Martinique. In the dark, these pyroclastic flows glowed red, Pyroclastic flows that contain a much higher proportion of gas to rock are known as fully dilute pyroclastic density currents or pyroclastic surges. The lower density sometimes allows them to flow over higher topographic features or water such as ridges, hills, rivers and seas. They may also contain steam, water and rock at less than 250 °C, cold pyroclastic surges can occur when the eruption is from a vent under a shallow lake or the sea. A pyroclastic flow is a type of gravity current, in literature they are sometimes abbreviated to PDC. There are several mechanisms that can produce a flow, Fountain collapse of an eruption column from a Plinian eruption. In such an eruption, the forcefully ejected from the vent heats the surrounding air. If the erupted jet is unable to heat the air sufficiently, convection currents will not be strong enough to carry the plume upwards and it falls. Fountain collapse of an eruption column associated with a Vulcanian eruption The gas and projectiles create a cloud that is denser than the surrounding air, frothing at the mouth of the vent during degassing of the erupted lava. This can lead to the production of a rock called ignimbrite and this occurred during the eruption of Novarupta in 1912. Gravitational collapse of a dome or spine, with subsequent avalanches. The directional blast when part of a volcano collapses or explodes, as distance from the volcano increases, this rapidly transforms into a gravity-driven current. The volumes range from a few hundred meters to more than a thousand cubic kilometres. The larger ones can travel for hundreds of kilometres, although none on that scale have occurred for several hundred thousand years, most pyroclastic flows are around one to ten cubic kilometres and travel for several kilometres
28.
Mount Pinatubo
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Its eruptive history was unknown to most before the pre-eruption volcanic activities of 1991, just before June. Pinatubo was heavily eroded, inconspicuous and obscured from view and it was covered with dense forests which supported a population of several thousand indigenous Aetas. The volcanos Ultra Plinian eruption on June 15,1991 produced the second-largest terrestrial eruption of the 20th century after the 1912 eruption of Novarupta in the Alaska Peninsula. Complicating the eruption was the arrival of Typhoon Yunya, bringing a lethal mix of ash and rain to towns. Predictions at the onset of the eruption led to the evacuation of tens of thousands of people from the surrounding areas. Surrounding areas were damaged by pyroclastic surges, ash falls. This caused extensive destruction to infrastructure and changed river systems for years after the eruption, the effects of the eruption were felt worldwide. It ejected roughly 10,000,000,000 tonnes or 10 km3 of magma and it injected more particulate into the stratosphere than any eruption since Krakatoa in 1883. Over the following months, the aerosols formed a layer of sulfuric acid haze. Global temperatures dropped by about 0.5 °C in the years 1991–93, the volcano is 87 km northwest of Manila, the capital of the Philippines. Near Mount Pinatubo, the United States maintained two military bases in the region. The U. S. Naval Base Subic Bay was 37 km south of Pinatubo, the volcano is near to about 6 million people. It is part of a chain of volcanoes lie along the western side of the edge of the island of Luzon called the Zambales Mountains. Pinatubo belongs to the Cabusilan sub-range of the Zambales Mountains, which consists of Mt. Cuadrado, Mt. Negron, Mt. Mataba and they are subduction volcanoes, formed by the Eurasian Plate sliding under the Philippine Mobile Belt along the Manila Trench to the west. Mount Pinatubo and the volcanoes on this volcanic belt arise due to magmatic occlusion from this subduction plate boundary. Pinatubo is flanked on the west by the Zambales Ophiolite Complex, the Tarlac Formation north, east and southeast of Pinatubo consists of marine, nonmarine and volcanoclastic sediments formed in the late Miocene and Pliocene. He recognized two life histories of the mountain, which he classified as ancestral and modern Pinatubo, activity of Ancestral Pinatubo seems to have begun about 1.1 million years ago and probably ended tens of thousands of years or more before the birth of Modern Pinatubo. Much of the land around the present volcano consists of remnants of ancestral Pinatubo
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Philippines
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The Philippines, officially the Republic of the Philippines, is a sovereign island country in Southeast Asia situated in the western Pacific Ocean. It consists of about 7,641 islands that are categorized broadly under three main geographical divisions from north to south, Luzon, Visayas, and Mindanao, the capital city of the Philippines is Manila and the most populous city is Quezon City, both part of Metro Manila. The Philippines has an area of 300,000 square kilometers, and it is the eighth-most populated country in Asia and the 12th most populated country in the world. As of 2013, approximately 10 million additional Filipinos lived overseas, multiple ethnicities and cultures are found throughout the islands. In prehistoric times, Negritos were some of the archipelagos earliest inhabitants and they were followed by successive waves of Austronesian peoples. Exchanges with Chinese, Malay, Indian, and Islamic nations occurred, then, various competing maritime states were established under the rule of Datus, Rajahs, Sultans or Lakans. The arrival of Ferdinand Magellan in Homonhon, Eastern Samar in 1521 marked the beginning of Hispanic colonization, in 1543, Spanish explorer Ruy López de Villalobos named the archipelago Las Islas Filipinas in honor of Philip II of Spain. With the arrival of Miguel López de Legazpi from Mexico City, in 1565, the Philippines became part of the Spanish Empire for more than 300 years. This resulted in Roman Catholicism becoming the dominant religion, during this time, Manila became the western hub of the trans-Pacific trade connecting Asia with Acapulco in the Americas using Manila galleons. Aside from the period of Japanese occupation, the United States retained sovereignty over the islands until after World War II, since then, the Philippines has often had a tumultuous experience with democracy, which included the overthrow of a dictatorship by a non-violent revolution. It is a member of the United Nations, World Trade Organization, Association of Southeast Asian Nations, the Asia-Pacific Economic Cooperation forum. It also hosts the headquarters of the Asian Development Bank, the Philippines was named in honor of King Philip II of Spain. Spanish explorer Ruy López de Villalobos, during his expedition in 1542, named the islands of Leyte, eventually the name Las Islas Filipinas would be used to cover all the islands of the archipelago. Before that became commonplace, other such as Islas del Poniente. The official name of the Philippines has changed several times in the course of its history, during the Philippine Revolution, the Malolos Congress proclaimed the establishment of the República Filipina or the Philippine Republic. From the 1898 Treaty of Paris, the name Philippines began to appear, since the end of World War II, the official name of the country has been the Republic of the Philippines. The metatarsal of the Callao Man, reliably dated by uranium-series dating to 67,000 years ago is the oldest human remnant found in the archipelago to date and this distinction previously belonged to the Tabon Man of Palawan, carbon-dated to around 26,500 years ago. Negritos were also among the archipelagos earliest inhabitants, but their first settlement in the Philippines has not been reliably dated, there are several opposing theories regarding the origins of ancient Filipinos
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Tephra
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Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts, once clasts have fallen to the ground they remain as tephra unless hot enough to fuse together into pyroclastic rock or tuff. Tephra mixed in with precipitation can also be acidic and cause acid rain, the use of tephra layers, which bear their own unique chemistry and character, as temporal marker horizons in archaeological and geological sites is known as tephrochronology. The word tephra and pyroclast both derive from Greek, τέφρα tephra means ash, while the word pyroclast is derived from the Greek πῦρ, meaning fire, media related to Tephra at Wikimedia Commons How Volcanoes Work Volcanic Materials Identification
31.
1815 eruption of Mount Tambora
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The 1815 eruption of Mount Tambora was one of the most powerful eruptions in recorded history and is the most recent known VEI-7 event. The eruption column lowered global temperatures, and some believe this led to global cooling. The eruption resulted in a period of significant climate change that led to various cases of extreme weather. Several climate forcings coincided and interacted in a manner that has not been observed since. Although the link between the climate changes and the Tambora event has been established by various scientists, the understanding of the processes involved is incomplete. Mount Tambora experienced several centuries of dormancy before 1815, as the result of the cooling of hydrous magma in a closed magma chamber. Inside the chamber at depths between 1.5 and 4.5 km, the exsolution of a high-pressure fluid magma formed during cooling, overpressure of the chamber of about 4, 000–5,000 bar was generated, and the temperature ranged from 700 to 850 °C. In 1812, the volcano began to rumble and generated a dark cloud, on the morning of 6 April, volcanic ash began to fall in East Java with faint detonation sounds lasting until 10 April. What was first thought to be the sound of firing guns was heard on 10 April on Sumatra more than 2,600 km away, at about 7 pm on 10 April, the eruptions intensified. Three columns of flame rose up and merged, the whole mountain was turned into a flowing mass of liquid fire. Pumice stones of up to 20 cm in diameter started to rain down around 8 pm, pyroclastic flows cascaded down the mountain to the sea on all sides of the peninsula, wiping out the village of Tambora. Loud explosions were heard until the evening,11 April. The ash veil had spread as far as West Java and South Sulawesi, a nitrous odour was noticeable in Batavia and heavy tephra-tinged rain fell, finally receding between 11 and 17 April. The first explosions were heard on this Island in the evening of 5 April, they were noticed in every quarter, the explosion is estimated to have been a VEI-7. An estimated 41 km3 of pyroclastic trachyandesite were ejected, weighing about 10 billion tonnes and this has left a caldera measuring 6–7 km across and 600–700 m deep. The density of ash in Makassar was 636 kg/m³. Before the explosion, Mount Tambora was about 4,300 m high, after the explosion, it measured only 2,851 m. The 1815 Tambora eruption is the largest observed eruption in recorded history, the explosion was heard 2,600 km away, and ash fell at least 1,300 km away
32.
Mount Tambora
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Mount Tambora is an active stratovolcano which is a peninsula of and the highest peak on the island of Sumbawa in Indonesia. Sumbawa is flanked both to the north and south by oceanic crust, and Tambora was formed by the subduction zone beneath it. This raised Mount Tambora as high as 4,300 m, after a large magma chamber inside the mountain filled over the course of several decades, volcanic activity reached a historic climax in the eruption of 10 April 1815. This eruption had a volcanic explosivity index of 7, the only unambiguously confirmed VEI-7 eruption since the Lake Taupo eruption in about AD180, Tamboras last eruption was in 1967. With an estimated volume of 160 km3, Tamboras 1815 outburst is the largest volcanic eruption in recorded history. The explosion was heard on Sumatra, more than 2,000 km away, heavy volcanic ash falls were observed as far away as Borneo, Sulawesi, Java, and the Maluku Islands. Most of the deaths from the eruption were from starvation and disease, as the eruptive fallout ruined agricultural productivity in the local region. The death toll was at least 71,000 people, of whom 11, 000–12,000 were killed directly by the eruption, crops failed and livestock died in much of the Northern Hemisphere, resulting in the worst famine of the 19th century. During an excavation in 2004, a team of archaeologists discovered cultural remains buried by the 1815 eruption and they were kept intact beneath the 3-metre-deep pyroclastic deposits. At the site, dubbed the Pompeii of the East, the artifacts were preserved in the positions they had occupied in 1815, Mount Tambora is on Sumbawa Island, part of the Lesser Sunda Islands. It is a segment of the Sunda Arc, a string of islands that forms the southern chain of the Indonesian archipelago. Tambora forms the Sanggar peninsula on Sumbawa, at the north of the peninsula is the Flores Sea, and at the south is Saleh Bay,86 km long and 36 km wide. At the mouth of Saleh Bay is a 30, 000-hectare islet called Moyo which has a guest shelter or luxurious resort where celebrities such as Princess Diana once stayed. Besides its interest for seismologists and volcanologists, who monitor the mountains activity and it also attracts tourists for hiking and wildlife activities. The two nearest cities are Dompu and Bima, three concentrations of villages are around the mountain slope. At the east is Sanggar village, to the northwest are Doro Peti and Pesanggrahan villages, three ascent routes are used to reach the caldera. The first route starts from Doro Mboha village south of the mountain, the end of this route is the southern part of the caldera at 1,950 m, reachable by a hiking track. This location is used as a base camp to monitor the volcanic activity
33.
1883 eruption of Krakatoa
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The 1883 eruption was one of the deadliest and most destructive volcanic events in recorded history. At least 36,417 deaths are attributed to the eruption, significant additional effects were also felt around the world in the days and weeks after the volcanos destruction. In the years before the 1883 eruption, seismic activity around the Krakatoa volcano was intense, beginning May 20,1883, steam venting began to occur regularly from Perboewatan, the northernmost of the islands three cones. Eruptions of ash reached an altitude of 6 km and explosions could be heard in New Batavia 160 km away. Activity died down by the end of May, and there was no recorded activity for several weeks. Eruptions at Krakatoa started again around June 16, with loud explosions, on June 24, a prevailing east wind cleared the cloud, and two ash columns could be seen issuing from Krakatoa. The seat of the eruption is believed to have been a new vent or vents that formed between Perboewatan and Danan, the violence of the ongoing eruptions caused tides in the vicinity to be unusually high, and ships at anchor had to be moored with chains. Earthquakes were felt at Anyer, Banten, and ships began to report large pumice masses to the west in the Indian Ocean, on August 11, a Dutch topographical engineer, Captain H. J. G. Ferzenaar, investigated the Krakatoa islands. He noted three major ash columns, which obscured the western part of the island, and steam plumes from at least eleven other vents, mostly between Danan and Rakata. When he landed, he noted an ash layer about 0.5 m thick, and he advised against any further landings. The next day, a passing to the north reported a new vent only a few meters above sea level. By August 25, the Krakatoa eruptions intensified, at about 13,00 on August 26, the volcano went into its paroxysmal phase. By 14,00, a cloud of ash could be seen 27 km high. At this point, the eruption was virtually continuous and explosions could be heard every ten minutes or so, ships within 20 km of the volcano reported heavy ash fall, with pieces of hot pumice up to 10 cm in diameter landing on their decks. Between 18,00 and 19,00 hours, a tsunami hit the shores of Java and Sumatra. On August 27, four enormous explosions occurred, at 5,30 am, the first explosion was at Perboewatan, triggering a tsunami heading straight to Telok Betong, now known as Bandar Lampung. At 6,44 am, Krakatoa exploded again at Danan, the third explosion has been reported as the loudest sound heard in historic times. The loudness of the blast heard 160 km from the volcano has been calculated to have been 180 dB, each explosion was accompanied by tsunamis estimated to have been over 30 meters high in places
34.
Indonesia
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Indonesia, officially the Republic of Indonesia, is a unitary sovereign state and transcontinental country located mainly in Southeast Asia with some territories in Oceania. Situated between the Indian and Pacific oceans, it is the worlds largest island country, with more than seventeen thousand islands. At 1,904,569 square kilometres, Indonesia is the worlds 14th-largest country in terms of area and worlds 7th-largest country in terms of combined sea. It has an population of over 260 million people and is the worlds fourth most populous country. The worlds most populous island, Java, contains more than half of the countrys population, Indonesias republican form of government includes an elected legislature and president. Indonesia has 34 provinces, of which five have Special Administrative status and its capital and countrys most populous city is Jakarta, which is also the most populous city in Southeast Asia and the second in Asia. The country shares land borders with Papua New Guinea, East Timor, other neighbouring countries include Singapore, Vietnam, the Philippines, Australia, Palau, and the Indian territory of the Andaman and Nicobar Islands. Despite its large population and densely populated regions, Indonesia has vast areas of wilderness that support the second highest level of biodiversity. The country has abundant natural resources like oil and natural gas, tin, copper, agriculture mainly produces rice, palm oil, tea, coffee, cacao, medicinal plants, spices and rubber. Indonesias major trading partners are Japan, United States, China, the Indonesian archipelago has been an important region for trade since at least the 7th century, when Srivijaya and then later Majapahit traded with China and India. Local rulers gradually absorbed foreign cultural, religious and political models from the early centuries CE, Indonesian history has been influenced by foreign powers drawn to its natural resources. Indonesia consists of hundreds of native ethnic and linguistic groups. The largest – and politically dominant – ethnic group are the Javanese, a shared identity has developed, defined by a national language, ethnic diversity, religious pluralism within a Muslim-majority population, and a history of colonialism and rebellion against it. Indonesias national motto, Bhinneka Tunggal Ika, articulates the diversity that shapes the country, Indonesias economy is the worlds 16th largest by nominal GDP and the 8th largest by GDP at PPP, the largest in Southeast Asia, and is considered an emerging market and newly industrialised country. Indonesia has been a member of the United Nations since 1950, Indonesia is a member of the G20 major economies and World Trade Organization. The name Indonesia derives from the Greek name of the Indós, the name dates to the 18th century, far predating the formation of independent Indonesia. In 1850, George Windsor Earl, an English ethnologist, proposed the terms Indunesians—and, his preference, in the same publication, one of his students, James Richardson Logan, used Indonesia as a synonym for Indian Archipelago. However, Dutch academics writing in East Indies publications were reluctant to use Indonesia, they preferred Malay Archipelago, the Netherlands East Indies, popularly Indië, the East, and Insulinde
35.
Krakatoa
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Krakatoa, or Krakatau, is a volcanic island situated in the Sunda Strait between the islands of Java and Sumatra in the Indonesian province of Lampung. The explosion is considered to be the loudest sound heard in modern history. The shock waves from the explosion were recorded on barographs worldwide for days afterward, in 1927 a new island, Anak Krakatau, or Child of Krakatoa, emerged from the caldera formed in 1883 and is the current location of eruptive activity. The most notable eruptions of Krakatoa culminated in a series of explosions over August 26–27,1883. The 1883 eruption ejected approximately 25 km3 of rock, the cataclysmic explosion was heard 4,800 km away in Alice Springs, as well as on the island of Rodrigues near Mauritius,4,653 km to the west. According to the records of the Dutch East Indies colony,165 villages and towns were destroyed near Krakatoa. At least 36,417 people died, and many thousands were injured. The eruption destroyed two-thirds of the island of Krakatoa, eruptions in the area since 1927 have built a new island at the same location, named Anak Krakatau. Periodic eruptions have continued since, with recent eruptions in 2009,2010,2011, as of late 2011, this island has a radius of roughly 2 kilometres, and a high point of about 324 metres above sea level, growing 5 metres each year. About two dozen variants have found, including Crackatouw, Cracatoa, and Krakatao. The first known appearance of the spelling Krakatau was by Wouter Schouten, the origin of the Indonesian name Krakatau is uncertain. The Smithsonian Institutions Global Volcanism Program cites the Indonesian name, Krakatau, as the correct name, while Krakatoa is more common in the English-speaking world, the Indonesian Krakatau tends to be favored by others, including geologists. Indonesia has over 130 active volcanoes, the most of any nation and they make up the axis of the Indonesian island arc system, which was produced by northeastward subduction of the Indo-Australian Plate. A majority of volcanoes lie along Indonesias two largest islands, Java and Sumatra. These two islands are separated by the Sunda Strait, which is located at a bend in the axis of the island arc. At some point in prehistory, an earlier caldera-forming eruption had occurred, leaving as remnants Verlaten, Lang, Poolsche Hoed, later, at least two more cones formed and eventually joined with Rakata, forming the main island of Krakatoa. At the time of the 1883 eruption, the Krakatoa group comprised Lang, Verlaten, and Krakatoa itself, there were also the tree-covered islet near Lang and several small rocky islets or banks between Krakatoa and Verlaten. There were three volcanic cones on Krakatoa island, Rakata, to the south, Danan, near the center, and Perboewatan, to the north
36.
Mount Katmai
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Mount Katmai is a large stratovolcano on the Alaska Peninsula in southern Alaska, located within Katmai National Park and Preserve. It is about 6.3 miles in diameter with a central lake-filled caldera about 3 by 2 mi in area, the caldera rim reaches a maximum elevation of 6,716 feet. In 1975 the surface of the lake was at an elevation of about 4,220 feet. The mountain is located in Kodiak Island Borough, very close to its border with Lake, Mount Katmai is one of five vents encircling the Novarupta volcano, source of the VEI6 eruption and associated voluminous pyroclastic flows in 1912. The volcano has caused ten known fatalities due to gas exposure, Katmai consists chiefly of lava flows, pyroclastic rocks, and non-welded to agglutinated air fall. The Quaternary volcanic rocks at Katmai and adjacent cones are less than 5,000 ft thick, much of the volcano is mantled by snow and ice and several valley glaciers radiate out from the flanks. The eruption actually took place at a vent about 6 mi to the west of Mount Katmai, during over 60 hours, the volcano erupted an estimated 28 km³ of ash flows and tephra representing 13 km³ of magma volume. The withdrawal of magma beneath Katmai resulted in the collapse of the summit area and it was visible at the time of the expedition in 1916, but has since been submerged by the crater lake. Still, the eruption from Katmai had a VEI of 3, in 1919, geologists noted a lake covering a large part of the caldera floor, but by 1923 the lake was gone and numerous fumaroles, mud pots, and a large mud geyser had replaced it. The lake has since refilled to a depth of over 800 ft, small glaciers have also formed on a bench within the caldera beside the lake. Pumice still floats on Naknek Lake nearby, list of volcanoes in the United States Katmai. Alaska Volcano Observatory, Katmai Wood, Charles A. Kienle, Jürgen, a narrative of the eruption of June 1912 and its effects on the town of Kodiak and its community, taken from letters, diaries and notes written at the time. London, New York and Toronto, Abelard-Schuman, hildreth, W. J. Fierstein, and J. E. Robinson. Geologic map of the Katmai Volcanic Cluster, Katmai National Park, reston, VA, U. S. Department of the Interior, U. S. Geological Survey
37.
Volcanic plug
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A volcanic plug, also called a volcanic neck or lava neck, is a volcanic object created when magma hardens within a vent on an active volcano. When present, a plug can cause an extreme build-up of pressure if rising volatile-charged magma is trapped beneath it, glacial erosion can lead to exposure of the plug on one side, while a long slope of material remains on the opposite side. Such landforms are called crag and tail, if a plug is preserved, erosion may remove the surrounding rock while the erosion-resistant plug remains, producing a distinctive upstanding landform. An example of two volcanic plugs can be found at the Pitons, in Saint Lucia, as they rise out of the eastern Caribbean Sea. Near the village of Rhumsiki in the Far North Province of Cameroon, spectacular volcanic plugs are present in the center of La Gomera island in the Canary Islands archipelago, within the Garajonay National Park. In New Zealands South Island, Ōnawe Peninsula on Banks Peninsula is a prominent volcanic plug, in Australia, the The Nut in Tasmania is a further example, along with Mount Warning. Borgarvirki is a volcanic plug located in north Iceland, a volcanic plug is situated in the town of Motta SantAnastasia in Italy. Saint Michel dAiguilhe chapel, whose construction started in 969, near Le Puy-en-Velay in France, the volcanic plug rises about 85 metres above the surroundings. Another building on a plug is the 14th century Trosky Castle in the Czech Republic. Rockall, a small, uninhabited, remote islet in the North Atlantic Ocean, is also a volcanic plug, in the United Kingdom, two examples of a building on a volcanic plug are the Castle Rock in Edinburgh, Scotland, and Deganwy Castle, Wales. The Law, Dundee, Ailsa Craig, Bass Rock, North Berwick Law, there are over 30 volcanic plugs in Northern Ireland, including Slemish in Ballymena, Tievebulliagh, Scawt Hill, Carrickarede, Scrabo and Slieve Gallion. Examples of volcanic plugs in the United States include Morro Rock, California and Laurel Hill, Devils Tower in Wyoming, as well as Little Devils Postpile located in Yosemite National Park, are also thought to be a volcanic plug by many geologists. Another example of a plug in the eastern USA is the highly eroded Starks Knob basaltic structure located along the Hudson River near Saratoga Springs. However, some geologists believe Starks Knob is not a plug at all, the origin of Devils Tower is not totally clear. Although it is admitted that it was formed by igneous intrusion, it is not necessarily a volcanic plug. In New Mexico, Shiprock is a further example, the Pitons of Saint Lucia, in the eastern Caribbean Sea are two volcanic plugs that rise abruptly out of the sea and are part of a UNESCO World Heritage site. The highest mountain plug rises to a height of nearly 760 metres, in Canada, the Castle Rock, located in British Columbia, is a volcanic plug that had volatile-charged magma still beneath it, leading to a Volcanic Explosivity Index 2 eruption
38.
Nile
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The Nile is a major north-flowing river in northeastern Africa. It is generally regarded as the longest river in the world, in particular, the Nile is the primary water source of Egypt and Sudan. The Nile has two tributaries, the White Nile and Blue Nile. The White Nile is considered to be the headwaters and primary stream of the Nile itself, the Blue Nile, however, is the source of most of the water and silt. The White Nile is longer and rises in the Great Lakes region of central Africa and it flows north through Tanzania, Lake Victoria, Uganda and South Sudan. The Blue Nile begins at Lake Tana in Ethiopia and flows into Sudan from the southeast, the two rivers meet just north of the Sudanese capital of Khartoum. The northern section of the river flows north almost entirely through the Sudanese desert to Egypt, then ends in a large delta, Egyptian civilization and Sudanese kingdoms have depended on the river since ancient times. Most of the population and cities of Egypt lie along those parts of the Nile valley north of Aswan, in the ancient Egyptian language, the Nile is called Ḥpī or Iteru, meaning river. In Coptic, the words piaro or phiaro meaning the river come from the ancient name. The English name Nile and the Arabic names en-Nîl and an-Nîl both derive from the Latin Nilus and the Ancient Greek Νεῖλος, beyond that, however, the etymology is disputed. One possible etymology derives it from a Semitic Nahal, meaning river, the standard English names White Nile and Blue Nile, to refer to the rivers source, derive from Arabic names formerly applied only to the Sudanese stretches which meet at Khartoum. Above Khartoum, the Nile is also known as the White Nile, at Khartoum the river is joined by the Blue Nile. The White Nile starts in equatorial East Africa, and the Blue Nile begins in Ethiopia, both branches are on the western flanks of the East African Rift. The drainage basin of the Nile covers 3,254,555 square kilometers, the source of the Nile is sometimes considered to be Lake Victoria, but the lake has feeder rivers of considerable size. It is either the Ruvyironza, which emerges in Bururi Province, Burundi, or the Nyabarongo, the two feeder rivers meet near Rusumo Falls on the Rwanda-Tanzania border. Gish Abay is reportedly the place where the water of the first drops of the Blue Nile develop. The Nile leaves Lake Nyanza at Ripon Falls near Jinja, Uganda and it flows north for some 130 kilometers, to Lake Kyoga. For the remaining part it flows westerly through the Murchison Falls until it reaches the very northern shores of Lake Albert where it forms a significant river delta
39.
Valley of Ten Thousand Smokes
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The Valley of Ten Thousand Smokes is a valley within Katmai National Park and Preserve in Alaska which is filled with ash flow from the eruption of Novarupta on June 6–8,1912. Following the eruption, thousands of fumaroles vented steam from the ash, the 1912 eruption was the largest eruption by volume in the 20th century, erupting about 13 cubic kilometers of material. Following the eruption, the summit of Mount Katmai subsided about 1,200 meters, Katmai is a stratovolcano, formed from alternating layers of lava flows and pyroclastic rocks. The presence of materials indicates that some Katmai eruptions have been explosive. The subsidence of the summit to form the caldera and the extraordinarily energetic earthquakes accompanying the 1912 eruption are evidence of this. The ash-filled valley covers a 40-square-mile area and is up to 700 feet deep, in places deep canyons have been cut by the River Lethe, allowing observers to see the ash flow strata. Since the ash has cooled, most of the fumaroles are now extinct, the signs of volcanic activity are still visible on nearby hills. Katmais most recent eruption was in 1927, but there have been non-eruptive events as recent as 2003, the Alaska Volcano Observatory still monitors Katmais activity as part of the Katmai Cluster, where there are 5 active stratovolcanos within 15 kilometers of Katmai. Visitors to the valley most commonly arrive via bus along the 20-mile road from Brooks Camp, the valley is a source of creative exploration by photographers and naturalists. Alaska Volcano Observatory page on Katmai Maps of region
40.
National Geographic Society
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The National Geographic Society, headquartered in Washington, D. C. United States, is one of the largest nonprofit scientific and educational institutions in the world and its interests include geography, archaeology and natural science, the promotion of environmental and historical conservation, and the study of world culture and history. In partnership with 21st Century Fox, the Society operates the magazine, TV channels, a website that features extra content and worldwide events, the National Geographic Society was founded in 1888 to increase and diffuse geographic knowledge. The Society believes in the power of science, exploration and storytelling to change the world, National Geographic is governed by a board of trustees, whose 21 members include distinguished educators, business executives, former government officials and conservationists. The organization sponsors and funds research and exploration. National Geographic maintains a museum for the public in its Washington and its Education Foundation gives grants to education organizations and individuals to improve geography education. Its Committee for Research and Exploration has awarded more than 11,000 grants for scientific research, National Geographic has retail stores in Washington, D. C. The locations outside of the United States are operated by Worldwide Retail Store S. L and it also publishes other magazines, books, school products, maps, and Web and film products in numerous languages and countries. National Geographics various media properties reach more than 280 million people monthly, the National Geographic Society began as a club for an elite group of academics and wealthy patrons interested in travel. After preparing a constitution and a plan of organization, the National Geographic Society was incorporated two weeks later on January 27, Gardiner Greene Hubbard became its first president and his son-in-law, Alexander Graham Bell, succeeded him in 1897. Bell and Gilbert Hovey Grosvenor devised the successful marketing notion of Society membership, the current National Geographic Society president and CEO is Gary E. Knell. The chairman of the board of trustees is John Fahey, the editor-in-chief of National Geographic magazine is Susan Goldberg. Gilbert Melville Grosvenor, a chairman of the Society board of trustees received the Presidential Medal of Freedom in 2005 for his leadership in geography education. In 2004, the National Geographic Society headquarters in Washington, D. C. was one of the first buildings to receive a Green certification from Global Green USA. The National Geographic received the prestigious Prince of Asturias Award for Communication and Humanities in October 2006 in Oviedo, in 2013 the society was investigated for possible violation of the Foreign Corrupt Practices Act relating to their close association with an Egyptian government official responsible for antiquities. This new, for-profit corporation, will own National Geographic and other magazines, as reported by The Guardian, a spokesman for National Geographic in a November 2,2015 e-mail statement, briefly discussed the rationale for the staff reductions as part of the. Process of reorganizing in order to move forward following the closing the National Geographic Partners deal. Additional specifics were provided to Photo District News by M. J. Jacobsen, National Geographic’s SVP of communications, similar to the contents of a formal announcement by the two companies
41.
Fumarole
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A fumarole is an opening in a planets crust, often in areas surrounding volcanoes, which emits steam and gases such as carbon dioxide, sulfur dioxide, hydrogen chloride, and hydrogen sulfide. The steam forms when superheated water vaporizes as its pressure drops when it emerges from the ground, the name solfatara, from the Italian solfo, sulfur, is given to fumaroles that emit sulfurous gases. Fumaroles may occur along tiny cracks or long fissures, in clusters or fields. A fumarole field is an area of springs and gas vents where magma or hot igneous rocks at shallow depth release gases or interact with groundwater. From the perspective of groundwater, a fumarole could be described as a hot spring that boils off all its water before the water reaches the surface. Fumaroles may persist for decades or centuries if located above a persistent heat source, the Valley of Ten Thousand Smokes, for example, was formed during the 1912 eruption of Novarupta in Alaska. Initially, thousands of fumaroles occurred in the ash from the eruption. An estimated four thousand fumaroles exist within the boundaries of Yellowstone National Park in the United States, in April 2006 fumarole emissions killed three ski-patrol workers east of Chair 3 at Mammoth Mountain Ski Area in California. The workers were overpowered by toxic fumes that had accumulated in a crevasse they had fallen into, another example is an array of fumaroles in the Valley of Desolation in Morne Trois Pitons National Park in Dominica. Boiling Lake Mazuku Mofetta Mudpot Mud volcano USGS Photo Glossary, Fumarole Sulfur Mining on Gunung Welirang Volcano Chisholm, Hugh, ed. Fumarole
42.
King Salmon, Alaska
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King Salmon is a census-designated place in Bristol Bay Borough in the U. S. state of Alaska. It is two hundred and eighty-four miles southwest of Anchorage, as of the 2010 census the population was 374. It is home to Katmai National Park and Preserve, King Salmon is the borough seat of neighboring Lake and Peninsula Borough, but does not serve that purpose in its own borough, whose borough seat is in Naknek. King Salmon is on the bank of the Naknek River on the Alaska Peninsula, about 25 km upriver from Naknek. According to the United States Census Bureau, the CDP has an area of 171.0 square miles, King Salmon has a subarctic climate even though it is at 58 N. As of the census of 2000, there were 442 people,196 households, the population density was 2.6 people per square mile. There were 343 housing units at a density of 2.0 per square mile. The racial makeup of the CDP was 66. 29% White,1. 13% Black or African American,28. 96% Native American,0. 23% Asian,0. 23% from other races,0. 45% of the population were Hispanic or Latino of any race. 41. 3% of all households were made up of individuals and 1. 5% had someone living alone who was 65 years of age or older, the average household size was 2.26 and the average family size was 3.17. In the CDP, the population was out with 26. 2% under the age of 18,7. 0% from 18 to 24,35. 7% from 25 to 44,28. 1% from 45 to 64. The median age was 38 years, for every 100 females there were 122.1 males. For every 100 females age 18 and over, there were 131.2 males, the median income for a household in the CDP was $54,375, and the median income for a family was $64,375. Males had an income of $45,000 versus $35,500 for females. The per capita income for the CDP was $26,755, about 8. 8% of families and 12. 4% of the population were below the poverty line, including 17. 5% of those under age 18 and none of those age 65 or over. Katmai National Park and Preserve In the 1930s, the U. S. government built an air navigation silo at the site of present-day King Salmon, at the beginning of World War II, the U. S. Army Air Forces built an air base around the silo. It was maintained by the Civil Aeronautics Administration throughout the war, in the 1940s and 1950s, the U. S. Army Corps of Engineers constructed a 25 km long road from King Salmon to Naknek. Other government agencies, such as the National Park Service, Alaska Department of Fish and Game, the King Salmon Inn opened in 1956. King Salmon is now a government, transportation, and service and shipment center for the commercial red salmon, the Air Force base closed in 1993, and is kept in caretaker status by Anchorage-based Chugach Federal Solutions, Inc. King Salmon Airport is now a public access airport
43.
National Monument (United States)
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Historically, some national monuments were managed by the War Department. National monuments can be so designated through the power of the Antiquities Act of 1906, President Theodore Roosevelt used the act to declare Devils Tower in Wyoming as the first national monument. The Antiquities Act of 1906 resulted from concerns about protecting mostly prehistoric Native American ruins, the Act authorized permits for legitimate archaeological investigations and penalties for taking or destroying antiquities without permission. Among the next three monuments he proclaimed in 1906 was Petrified Forest in Arizona, another natural feature, in 1908, Roosevelt used the act to proclaim more than 800,000 acres of the Grand Canyon as a national monument. In 1918, President Woodrow Wilson proclaimed Katmai National Monument in Alaska, Katmai was later enlarged to nearly 2,800,000 acres by subsequent Antiquities Act proclamations and for many years was the largest national park system unit. Petrified Forest, Grand Canyon, and Katmai were among the national monuments later converted to national parks by Congress. Substantial opposition did not materialize until 1943, when President Franklin D. Roosevelt proclaimed Jackson Hole National Monument in Wyoming. He did this to accept a donation of lands acquired by John D. Rockefeller, roosevelts proclamation unleashed a storm of criticism about use of the Antiquities Act to circumvent Congress. A bill abolishing Jackson Hole National Monument passed Congress but was vetoed by Roosevelt, the proclamation authority was not used again anywhere until 1996, when President Bill Clinton proclaimed the Grand Staircase-Escalante National Monument in Utah. This action was unpopular in Utah, and bills were introduced to further restrict the presidents authority. To date, none of them have been enacted, presidents have used the Antiquities Acts proclamation authority not only to create new national monuments but to enlarge existing ones. For example, Franklin D. Roosevelt significantly enlarged Dinosaur National Monument in 1938, lyndon B. Johnson added Ellis Island to Statue of Liberty National Monument in 1965, and Jimmy Carter made major additions to Glacier Bay and Katmai National Monuments in 1978. Marine National Monument List of U. S. National Forests List of areas in the National Park System of the United States List of U. S
44.
Timeline of volcanism on Earth
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Some cooled the global climate, the extent of this effect depends on the amount of sulfur dioxide emitted. The topic in the background is an overview of the VEI, before the Holocene epoch, the criteria are less strict because of scarce data availability, partly since later eruptions have destroyed the evidence. So, the known large eruptions after the Paleogene period are listed, and especially those relating to the Yellowstone hotspot, the Santorini, only some eruptions before the Neogene period are listed. Active volcanoes such as Stromboli, Mount Etna and Kilauea do not appear on this list, some dangerous volcanoes in populated areas appear many times, so Santorini, six times and Yellowstone hotspot, twenty-one times. The Bismarck volcanic arc, New Britain, and the Taupo Volcanic Zone, New Zealand, in order to keep the list manageable, the eruptions in the Holocene on the link, Holocene Volcanoes in Kamchatka arent yet added, but they are listed in Peter L. The Holocene epoch begins 11,700 years BP and this is a sortable summary of 27 major eruptions in the last 2000 years with VEI ≥6, implying an average of about 1.3 per century. The count does not include the notable VEI5 eruptions of Mount St. Helens, date uncertainties, tephra volumes, and references are also not included. Note, Caldera names tend to change over time, for example, Okataina Caldera, Haroharo Caldera, Haroharo volcanic complex, Tarawera volcanic complex had the same magma source in the Taupo Volcanic Zone. Yellowstone Caldera, Henrys Fork Caldera, Island Park Caldera, Heise Volcanic Field had all Yellowstone hotspot as magma source,2.588 ± 0.005 million years BP, the Quaternary period and Pleistocene epoch begin. Eifel hotspot, Laacher See, Vulkan Eifel, Germany,12.9 ka, Emmons Lake Caldera, Aleutian Range,17 ka ±5, more than 50 km3 of tephra. Lake Barrine, Atherton Tableland, North Queensland, Australia, was formed over 17 ka, menengai, East African Rift, Kenya,29 ka Morne Diablotins, Commonwealth of Dominica, VEI6,30 ka. Kurile Lake, Kamchatka Peninsula, Russia, Golygin eruption, about 41.5 ka, VEI7 Maninjau Caldera, West Sumatra, VEI7, around 52 ka,220 to 250 cubic kilometers of tephra. Lake Toba, Sumatra, Indonesia, VEI8,73 ka ±4,2,500 to 3,000 cubic kilometers of tephra, atitlán Caldera, Guatemalan Highlands, Los Chocoyos eruption, formed in an eruption 84 ka, VEI7,300 km3 of tephra. Mount Aso, island of Kyūshū, Japan,90 ka, sierra La Primavera volcanic complex, Guadalajara, Jalisco, Mexico,95 ka,20 cubic kilometers of Tala Tuff. Mount Aso, island of Kyūshū, Japan,120 ka,80 km3 of tephra, Mount Aso, island of Kyūshū, Japan,140 ka,80 km3 of tephra. Puy de Sancy, Massif Central, central France, it is part of an ancient stratovolcano which has been inactive for about 220,000 years, Emmons Lake Caldera, Aleutian Range,233 ka, more than 50 km3 of tephra. Mount Aso, island of Kyūshū, Japan, caldera formed as a result of four huge caldera eruptions,270 ka,80 cubic kilometers of tephra, uzon-Geyzernaya calderas, Kamchatka Peninsula, Russia, 325-175 ka 20 km3 of ignimbrite deposits. Diamante Caldera–Maipo volcano complex, Argentina-Chile,450 ka,450 cubic kilometers of tephra, mono County, California, USA, Long Valley Caldera,758.9 ka ±1.8, VEI7,600 cubic kilometers of Bishop Tuff
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Mexico
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Mexico, officially the United Mexican States, is a federal republic in the southern half of North America. It is bordered to the north by the United States, to the south and west by the Pacific Ocean, to the southeast by Guatemala, Belize, and the Caribbean Sea, and to the east by the Gulf of Mexico. Covering almost two million square kilometers, Mexico is the sixth largest country in the Americas by total area, Mexico is a federation comprising 31 states and a federal district that is also its capital and most populous city. Other metropolises include Guadalajara, Monterrey, Puebla, Toluca, Tijuana, pre-Columbian Mexico was home to many advanced Mesoamerican civilizations, such as the Olmec, Toltec, Teotihuacan, Zapotec, Maya and Aztec before first contact with Europeans. In 1521, the Spanish Empire conquered and colonized the territory from its base in Mexico-Tenochtitlan, Three centuries later, this territory became Mexico following recognition in 1821 after the colonys Mexican War of Independence. The tumultuous post-independence period was characterized by instability and many political changes. The Mexican–American War led to the cession of the extensive northern borderlands, one-third of its territory. The Pastry War, the Franco-Mexican War, a civil war, the dictatorship was overthrown in the Mexican Revolution of 1910, which culminated with the promulgation of the 1917 Constitution and the emergence of the countrys current political system. Mexico has the fifteenth largest nominal GDP and the eleventh largest by purchasing power parity, the Mexican economy is strongly linked to those of its North American Free Trade Agreement partners, especially the United States. Mexico was the first Latin American member of the Organisation for Economic Co-operation and Development and it is classified as an upper-middle income country by the World Bank and a newly industrialized country by several analysts. By 2050, Mexico could become the fifth or seventh largest economy. The country is considered both a power and middle power, and is often identified as an emerging global power. Due to its culture and history, Mexico ranks first in the Americas. Mexico is a country, ranking fourth in the world by biodiversity. In 2015 it was the 9th most visited country in the world, Mexico is a member of the United Nations, the World Trade Organization, the G8+5, the G20, the Uniting for Consensus and the Pacific Alliance. Mēxihco is the Nahuatl term for the heartland of the Aztec Empire, namely, the Valley of Mexico, and its people, the Mexica and this became the future State of Mexico as a division of New Spain prior to independence. It is generally considered to be a toponym for the valley became the primary ethnonym for the Aztec Triple Alliance as a result. After New Spain won independence from Spain, representatives decided to name the new country after its capital and this was founded in 1524 on top of the ancient Mexica capital of Mexico-Tenochtitlan
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Global Volcanism Program
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The Smithsonian Institutions Global Volcanism Program documents Earths volcanoes and their eruptive history over the past 10,000 years. The GVP reports on current eruptions from around the world as well as maintaining a repository on active volcanoes. In this way, a context for the planets active volcanism is presented. Smithsonian reporting on current volcanic activity dates back to 1968, with the Center for Short-Lived Phenomena, the GVP is housed in the Department of Mineral Sciences, part of the National Museum of Natural History, on the National Mall in Washington, D. C. During the early stages of an eruption, the GVP acts as a clearinghouse of reports, data, the Weekly Volcanic Activity Report is a cooperative project between the Smithsonians Global Volcanism Program and the United States Geological Surveys Volcano Hazards Program. Notices of volcanic activity posted on the Report website are preliminary, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network The GVP also documents the last 10,000 years of Earths volcanism. The historic activity can guide perspectives on future events and on volcanoes showing activity. GVPs volcano and eruption databases constitute a foundation for all statements concerning locations, frequencies. Two editions of Volcanoes of the World, a regional directory, and were published based on the GVP data and interpretations
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Smithsonian Institution
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The Smithsonian Institution, established in 1846 for the increase and diffusion of knowledge, is a group of museums and research centers administered by the Government of the United States. Originally organized as the United States National Museum, that ceased to exist as an administrative entity in 1967. Additional facilities are located in Arizona, Maryland, Massachusetts, New York City, Texas, Virginia, more than 200 institutions and museums in 45 states, Puerto Rico, and Panama are Smithsonian Affiliates. The Institutions thirty million annual visitors are admitted without charge and its annual budget is around $1.2 billion with 2/3 coming from annual federal appropriations. Other funding comes from the Institutions endowment, private and corporate contributions, membership dues, and earned retail, concession, Institution publications include Smithsonian and Air & Space magazines. The British scientist James Smithson left most of his wealth to his nephew Henry James Hungerford, Congress officially accepted the legacy bequeathed to the nation, and pledged the faith of the United States to the charitable trust on July 1,1836. The American diplomat Richard Rush was dispatched to England by President Andrew Jackson to collect the bequest, Rush returned in August 1838 with 105 sacks containing 104,960 gold sovereigns. Once the money was in hand, eight years of Congressional haggling ensued over how to interpret Smithsons rather vague mandate for the increase, unfortunately, the money was invested by the US Treasury in bonds issued by the state of Arkansas which soon defaulted. The United States Exploring Expedition by the U. S. Navy circumnavigated the globe between 1838 and 1842, in 1846, the regents developed a plan for weather observation, in 1847, money was appropriated for meteorological research. The Institution became a magnet for young scientists from 1857 to 1866, the Smithsonian played a critical role as the U. S. partner institution in early bilateral scientific exchanges with the Academy of Sciences of Cuba. The Smithsonian Institution Building began construction in 1849, designed by architect James Renwick Jr. its interiors were completed by general contract Gilbert Cameron and the building opened in 1855. The Smithsonians first expansion came with construction of the Arts and Industries Building in 1881, Congress had promised to build a new structure for the museum if the 1876 Philadelphia Centennial Exposition generated enough income. It did, and the building was designed by architects Adolf Cluss and Paul Schulze, meigs of the United States Army Corps of Engineers. The National Zoological Park opened in 1889 to accommodate the Smithsonians Department of Living Animals and this structure was designed by the D. C. architectural firm of Hornblower & Marshall. More than 40 years would pass before the museum, the Museum of History. It was designed by the firm of McKim, Mead & White. That same year, the Smithsonian signed an agreement to take over the Cooper Union Museum for the Arts of Decoration, the National Portrait Gallery and the Smithsonian American Art Museum opened in the Old Patent Office Building on October 7,1968. The first new building to open since the National Museum of Natural History was the Hirshhorn Museum and Sculpture Garden
