Cleveland Volcano in the Aleutian Islands of Alaska photographed from the International Space Station

A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot, molten rock, ash, and gases to escape from below the surface. In Geology, a crust is the outermost solid shell of a planet or moon Volcanic activity involving the extrusion of rock tends to form mountains or features like mountains over a period of time. Extrusive refers to the mode of Igneous Volcanic rock formation in which hot Magma from inside the Earth flows out (extrudes onto the surface

Volcanoes are generally found where tectonic plates are pulled apart or come together. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere A mid-oceanic ridge, for example the Mid-Atlantic Ridge, has examples of volcanoes caused by "divergent tectonic plates" pulling apart; the Pacific Ring of Fire has examples of volcanoes caused by "convergent tectonic plates" coming together. A mid-ocean ridge or mid-oceanic ridge is an underwater Mountain range typically having a valley known as a Rift running along its axis formed by The Mid-Atlantic Ridge (MAR is a Mid-ocean ridge, a Divergent tectonic plate boundary located along the floor of the Atlantic Ocean. In Plate tectonics, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a In Plate tectonics, a convergent boundary – also known as a convergent plate boundary or a destructive plate boundary – is an actively deforming region By contrast, volcanoes are usually not created where two tectonic plates slide past one another. Volcanoes can also form where there is stretching and thinning of the Earth's crust (called "non-hotspot intraplate volcanism"), such as in the African Rift Valley, the Wells Gray-Clearwater Volcanic Field and the Rio Grande Rift in North America and the European Rhine Graben with its Eifel volcanoes. In Geology, a crust is the outermost solid shell of a planet or moon The East African Rift is part of the larger Great Rift Valley. The Wells Gray-Clearwater volcanic field, also called the Clearwater Cone Group, Monogenetic volcanic field in east-central British Columbia, Canada The Rio Grande runs a north-south course in New Mexico and Colorado The Rhine (Rhein Rijn Rhin Reno Rain Rhenus is one of the longest and most important Rivers in Europe at 1320 kilometres (820 mi with an average discharge The Eifel is a low mountain range in western Germany. It occupies parts of southwestern North Rhine-Westphalia and northwestern Rhineland-Palatinate

Volcanoes can be caused by "mantle plumes". A mantle plume is an upwelling of abnormally hot rock within the Earth's mantle. These so-called "hotspots" , for example at Hawaii, can occur far from plate boundaries. In Geology, a hotspot is a location on the Earth's surface that has experienced active volcanism for a long period of time The State of Hawaii ( or həˈwaɪʔiː Hawaiian: Mokuāina o Hawaii) is a state in the United States located on an Archipelago in the Hotspot volcanoes are also found elsewhere in the solar system, especially on rocky planets and moons. The Solar System consists of the Sun and those celestial objects bound to it by Gravity.

Plate tectonics and hotspots

Map showing the divergent plate boundaries (OSR – Oceanic Spreading Ridges) and recent sub aerial volcanoes.

Divergent plate boundaries

At the mid-oceanic ridges, two tectonic plates diverge from one another. A mid-ocean ridge or mid-oceanic ridge is an underwater Mountain range typically having a valley known as a Rift running along its axis formed by Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere New oceanic crust is being formed by hot molten rock slowly cooling and solidifying. Oceanic crust is the part of Earth's Lithosphere that surfaces in the Ocean basins The crust is very thin at mid-oceanic ridges due to the pull of the tectonic plates. The release of pressure due to the thinning of the crust leads to adiabatic expansion, and the partial melting of the mantle causing volcanism and creating new oceanic crust. This article covers adiabatic processes in Thermodynamics. For adiabatic processes in Quantum mechanics, see Adiabatic process (quantum mechanics The mantle is a part of an Astronomical object. The interior of the Earth, similar to the other Terrestrial planets, is Chemically divided Most divergent plate boundaries are at the bottom of the oceans, therefore most volcanic activity is submarine, forming new seafloor. In Plate tectonics, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a Black smokers or deep sea vents are an example of this kind of volcanic activity. A black smoker or sea vent is a type of Hydrothermal vent found on the Ocean floor. Where the mid-oceanic ridge is above sea-level, volcanic islands are formed, for example, Iceland. Iceland, officially the Republic of Iceland ( ( Ísland or Lýðveldið Ísland (

Lava enters Pacific at the Big Island of Hawaii

Convergent plate boundaries

Subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures The Pacific Ocean is the largest of the Earth 's Oceanic divisions The Island of Hawaii, also called the Big Island or Hawaii Island, is a volcanic Island in the U In Geology, a subduction zone is an area on Earth where two tectonic plates meet and move towards one another with one sliding underneath the other In this case, the oceanic plate subducts, or submerges under the continental plate forming a deep ocean trench just offshore. Water released from the subducting plate lowers the melting temperature of the overlying mantle wedge, creating magma. Magma (Plurals magmas and magmata) is molten rock that sometimes forms beneath the surface of the Earth (or any other Terrestrial planet This magma tends to be very viscous due to its high silica content, so often does not reach the surface and cools at depth. Viscosity is a measure of the resistance of a Fluid which is being deformed by either Shear stress or Extensional stress. The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide When it does reach the surface, a volcano is formed. Typical examples for this kind of volcano are Mount Etna and the volcanoes in the Pacific Ring of Fire.

Hotspots

Hotspots are not usually located on the ridges of tectonic plates, but above mantle plumes, where the convection of the Earth's mantle creates a column of hot material that rises until it reaches the crust, which tends to be thinner than in other areas of the Earth. In Geology, a hotspot is a location on the Earth's surface that has experienced active volcanism for a long period of time A mantle plume is an upwelling of abnormally hot rock within the Earth's mantle. Convection in the most general terms refers to the movement of molecules within Fluids (i EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 The mantle is a part of an Astronomical object. The interior of the Earth, similar to the other Terrestrial planets, is Chemically divided EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 The temperature of the plume causes the crust to melt and form pipes, which can vent magma. Magma (Plurals magmas and magmata) is molten rock that sometimes forms beneath the surface of the Earth (or any other Terrestrial planet Because the tectonic plates move whereas the mantle plume remains in the same place, each volcano becomes dormant after a while and a new volcano is then formed as the plate shifts over the hotspot. The Hawaiian Islands are thought to be formed in such a manner, as well as the Snake River Plain, with the Yellowstone Caldera being the part of the North American plate currently above the hotspot. The Hawaiian Islands, once known as the Sandwich Islands, form an Archipelago of 19 Islands and Atolls numerous smaller The Snake River Plain is a geologic feature located primarily in the American state of Idaho. The Yellowstone Caldera is the volcanic Caldera in Yellowstone National Park in the United States.

Indonesia - Lombok: Mount Rinjani - outbreak in 1994

Volcanic features

The most common perception of a volcano is of a conical mountain, spewing lava and poisonous gases from a crater at its summit. The Republic of Indonesia ( (Republik Indonesia is a Country in Southeast Asia. Lombok (population 2950105 in 2005) is an Island in West Nusa Tenggara province Indonesia. Mount Rinjani or Gunung Rinjani is an active Volcano in Indonesia on the island of Lombok. A cone is a three-dimensional Geometric shape that tapers smoothly from a flat round base to a point called the apex or vertex Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures Volcanic gases include a variety of substances given off by active (or at times by dormant Volcanoes These include gases trapped in cavities ( Vesicles) in A volcanic crater is a circular depression in the ground caused by volcanic activity This describes just one of many types of volcano, and the features of volcanoes are much more complicated. The structure and behavior of volcanoes depends on a number of factors. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater, whereas others present landscape features such as massive plateaus. In Volcanology, a lava dome or plug dome is a roughly circular Mound -shaped protrusion resulting from the slow eruption of Felsic Lava Landscape comprises the visible features of an area of land including physical elements such as Landforms living elements of flora and fauna abstract elements such as lighting In Geology and Earth science, a plateau, also called a high plateau or tableland, is an area of highland, usually consisting Vents that issue volcanic material (lava, which is what magma is called once it has escaped to the surface, and ash) and gases (mainly steam and magmatic gases) can be located anywhere on the landform. Volcanic ash consists of small Tephra, which are bits of pulverized rock and glass created by volcanic eruptions less than in diameter Plate tectonics and hotspots Divergent plate boundaries At the Many of these vents give rise to smaller cones such as Puʻu ʻŌʻō on a flank of Hawaii's Kīlauea. Puu Ōō (often written Puu Oo, and puʔu ʔoːʔoː (roughly "poo-oo oh-oh" is a cinder/spatter cone in the eastern Rift zone of the The State of Hawaii ( or həˈwaɪʔiː Hawaiian: Mokuāina o Hawaii) is a state in the United States located on an Archipelago in the Kīlauea (kiːlauea is an active Volcano in the Hawaiian Islands, one of five Shield volcanoes that together form the Island of Hawai{{okina}}i

Other types of volcano include cryovolcanoes (or ice volcanoes), particularly on some moons of Jupiter, Saturn and Neptune; and mud volcanoes, which are formations often not associated with known magmatic activity. A cryovolcano is literally an Icy Volcano. Cryovolcanoes form on Icy moons and possibly on other low- Temperature Astronomical objects Neptune ( English|AmE] ] is the eighth and farthest Planet from the Sun in the Solar System. Note See the Volcano article for information on Magmatic volcanoes such as Mount St Active mud volcanoes tend to involve temperatures much lower than those of igneous volcanoes, except when a mud volcano is actually a vent of an igneous volcano. Igneous rocks (etymology from Latin ignis, fire are rocks formed by solidification of cooled Magma (molten rock

Skjaldbreiður, a shield volcano whose name means "broad shield"

Shield volcanoes

Main article: Shield volcano

Shield volcanoes, so named for their broad, shield-like profiles, are formed by the eruption of low-viscosity lavas that can flow a great distance from a vent, but not generally explode catastrophically. Skjaldbreiður, meaning the broad shield in Icelandic, is an Icelandic mountain from whose name the term " Shield volcano " derives A shield volcano is a large Volcano with shallow-sloping sides The Hawaiian volcanic chain is a series of shield cones, and they are common in Iceland, as well. The State of Hawaii ( or həˈwaɪʔiː Hawaiian: Mokuāina o Hawaii) is a state in the United States located on an Archipelago in the Iceland, officially the Republic of Iceland ( ( Ísland or Lýðveldið Ísland (

Lava domes

Main article: Lava dome

Lava domes are built by slow eruptions of highly viscous lavas. In Volcanology, a lava dome or plug dome is a roughly circular Mound -shaped protrusion resulting from the slow eruption of Felsic Lava They are sometimes formed within the crater of a previous volcanic eruption (as in Mount Saint Helens), but can also form independently, as in the case of Lassen Peak. Mount St Helens is an active Stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States Lassen Peak (also known as Mount Lassen) is the southernmost active Volcano in the Cascade Range. Like stratovolcanoes, they can produce violent, explosive eruptions, but their lavas generally do not flow far from the originating vent.

Cinder cones

Main article: Volcanic cone

Volcanic cones or cinder cones result from eruptions that erupt mostly small pieces of scoria and pyroclastics (both resemble cinders, hence the name of this volcano type) that build up around the vent. Volcanic cones are among the simplest Volcano formations in the world Volcanic cones are among the simplest Volcano formations in the world A cinder cone or scoria cone is a steep conical Hill of volcanic fragments that accumulate around and downwind from a Volcanic vent. Scoria is a textural term for macrovesicular Volcanic rock. It is commonly but not exclusively Basaltic or andesitic in composition Pyroclastic rocks or pyroclastics (derived from the Greek πῦρ, meaning fire and κλαστός, meaning broken are Clastic rocks These can be relatively short-lived eruptions that produce a cone-shaped hill perhaps 30 to 400 meters high. Most cinder cones erupt only once. Cinder cones may form as flank vents on larger volcanoes, or occur on their own. Parícutin in Mexico and Sunset Crater in Arizona are examples of cinder cones. Parícutin (or Volcán de Parícutin also accented Paricutín by locals to more closely match the pronunciation of the native Purepecha name Parhicutini or spelled unaccented The United Mexican States ( or commonly Mexico (ˈmɛksɪkoʊ () is a federal constitutional Republic in North America. Sunset Crater is a Cinder cone located north of Flagstaff Arizona, in the United States. The State of Arizona ( is a state located in the southwestern region of the United States.

Mayon Volcano, a stratovolcano

Stratovolcanoes (composite volcano)

Main article: Strato volcano

Stratovolcanoes are tall conical mountains composed of lava flows and other ejecta in alternate layers, the strata that give rise to the name. A stratovolcano, also called a composite volcano is a tall conical Volcano composed of many layers of hardened Lava, Tephra, and Volcanic A stratovolcano, also called a composite volcano is a tall conical Volcano composed of many layers of hardened Lava, Tephra, and Volcanic In Geology and related fields a stratum (plural strata) is a layer of rock or Soil with internally consistent characteristics that distinguishes Stratovolcanoes are also known as composite volcanoes. Strato/composite volcanoes are made of cinders, ash and lava. The volcanoes are made by another volcano. Cinders and ash pile on top of each other, then lava flows on top and dries and then the process begins again. Classic examples include Mt. Fuji in Japan, Mount Mayon in the Philippines, and Mount Vesuvius and Stromboli in Italy. is the highest Mountain in Japan at.An Active volcano that last erupted in 1707–08 it straddles the boundary of Shizuoka and The Mayon Volcano is an active Stratovolcano in the Philippines on the Island of Luzon, in the province of Albay Mount Vesuvius (in Italian Monte Vesuvio and in Latin Mons Vesuvius) is an active Stratovolcano east of Naples Stromboli (Strongyle is a small island in the Tyrrhenian Sea, off the north coast of Sicily, containing one of the three active volcanoes in Italy Within a relatively short geologic time scale stratovolcanoes are more dangerous (see stratovolcano for a list of dangers). A stratovolcano, also called a composite volcano is a tall conical Volcano composed of many layers of hardened Lava, Tephra, and Volcanic

The Lake Toba volcano created a caldera 100 km long

Supervolcanoes

Main article: Supervolcano

Supervolcano is the popular term for a large volcano that usually has a large caldera and can potentially produce devastation on an enormous, sometimes continental, scale. Lake Toba ( Danau Toba) is a Lake and Supervolcano, 100 km long and 30 km wide and 505 m A supervolcano or super volcanic eruption is a Volcanic eruption which is Orders of magnitude greater than any volcano in historic times (generally accepted to be A caldera is a cauldron-like volcanic feature formed by the collapse of land following a volcanic eruption Such eruptions would be able to cause severe cooling of global temperatures for many years afterwards because of the huge volumes of sulfur and ash erupted. Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 They are the most dangerous type of volcano. Examples include Yellowstone Caldera in Yellowstone National Park of western USA, Lake Taupo in New Zealand and Lake Toba in Sumatra, Indonesia. The Yellowstone Caldera is the volcanic Caldera in Yellowstone National Park in the United States. Lake Taupo is a Lake situated in the North Island of New Zealand. New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island Lake Toba ( Danau Toba) is a Lake and Supervolcano, 100 km long and 30 km wide and 505 m Sumatra (also spelled Sumatera) is the sixth largest island in the world (approximately 470000 km² and is the largest island entirely in Indonesia (two The Republic of Indonesia ( (Republik Indonesia is a Country in Southeast Asia. Supervolcanoes are hard to identify centuries later, given the enormous areas they cover. Large igneous provinces are also considered supervolcanoes because of the vast amount of basalt lava erupted, but they are non-explosive because only non-explosive eruptions such as Kilauea produce basalt lava. Large Igneous provinces (LIPS were originally defined by Coffin and Eldholm (1992 as areas of Earth's surface that contain very large volumes of magmatic rocks (typically Basalt (bəˈsɔːlt ˈbeisɔːlt ˈbæsɔːlt is a common Extrusive Volcanic rock. Kīlauea (kiːlauea is an active Volcano in the Hawaiian Islands, one of five Shield volcanoes that together form the Island of Hawai{{okina}}i

Pillow lava (NOAA)

Submarine volcanoes

Main article: Submarine volcano

Submarine volcanoes are common features on the ocean floor. Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures The National Oceanic and Atmospheric Administration ( NOAA) is a scientific agency within the United States Department of Commerce focused on the conditions of the Submarine volcanoes are underwater fissures in the earth's surface from which magma can erupt Submarine volcanoes are underwater fissures in the earth's surface from which magma can erupt Some are active and, in shallow water, disclose their presence by blasting steam and rocky debris high above the surface of the sea. Many others lie at such great depths that the tremendous weight of the water above them prevents the explosive release of steam and gases, although they can be detected by hydrophones and discoloration of water because of volcanic gases. A hydrophone (Greek "hydro" = "water" and "phone" = "sound" is a Microphone designed to be used underwater for recording or listening Volcanic gases include a variety of substances given off by active (or at times by dormant Volcanoes These include gases trapped in cavities ( Vesicles) in Pumice rafts may also appear. A pumice raft is a floating raft of Pumice occasionally created by ocean-based Volcanic activity Even large submarine eruptions may not disturb the ocean surface. Because of the rapid cooling effect of water as compared to air, and increased buoyancy, submarine volcanoes often form rather steep pillars over their volcanic vents as compared to above-surface volcanoes. They may become so large that they break the ocean surface as new islands. Pillow lava is a common eruptive product of submarine volcanoes. Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures

Herðubreið, one of the tuyas in Iceland

Subglacial volcanoes

Main article: Subglacial volcano

Subglacial volcanoes develop underneath icecaps. Herðubreið is a Tuya in north-east Iceland at. It is situated in the Highlands of Iceland in the midst of the Ódáðahraun Desert A tuya is a type of distinctive flat-topped steep-sided Volcano formed when Lava erupts through a thick Glacier or Ice sheet. Iceland, officially the Republic of Iceland ( ( Ísland or Lýðveldið Ísland ( A subglacial volcano is a volcanic form produced by Subglacial eruptions or eruptions beneath the surface of a Glacier or Ice sheet which is then melted A subglacial volcano is a volcanic form produced by Subglacial eruptions or eruptions beneath the surface of a Glacier or Ice sheet which is then melted An ice cap is an Ice mass that covers less than 50 000 km² of land area (usually covering a highland area They are made up of flat lava flows atop extensive pillow lavas and palagonite. Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures Palagonite is an alteration product from the interaction of water with Volcanic glass of chemical composition similar to Basalt. When the icecap melts, the lavas on the top collapse leaving a flat-topped mountain. Then, the pillow lavas also collapse, giving an angle of 37. 5 degrees. These volcanoes are also called table mountains, tuyas or (uncommonly) mobergs. A tuya is a type of distinctive flat-topped steep-sided Volcano formed when Lava erupts through a thick Glacier or Ice sheet. Very good examples of this type of volcano can be seen in Iceland, however, there are also tuyas in British Columbia. British Columbia (ˌbrɪtɨʃ kəˈlʌmbiə ( BC) ( (la Colombie-Britannique C The origin of the term comes from Tuya Butte, which is one of the several tuyas in the area of the Tuya River and Tuya Range in northern British Columbia. Tuya Butte is a Tuya in the Tuya Range of north-central British Columbia. The Tuya Range is a range of Tuyas located in the Stikine Ranges of the Cassiar Mountains in the Canadian province of British Columbia Tuya Butte was the first such landform analyzed and so its name has entered the geological literature for this kind of volcanic formation. The Tuya Mountains Provincial Park was recently established to protect this unusual landscape, which lies north of Tuya Lake and south of the Jennings River near the boundary with the Yukon Territory. Tuya Mountains Provincial Park is a Provincial park in British Columbia, Canada. Yukon (ˈjuːkɒn is the westernmost and smallest of Canada's three territories.

Antarctica eruption

In January, 2008, the British Antarctic Survey (Bas) scientists led by Hugh Corr and David Vaughan, reported (in the journal Nature Geoscience) that 2,200 years ago, a volcano erupted under Antarctica ice sheet (based on airborne survey with radar images). The British Antarctic Survey (BAS is the United Kingdom 's national Antarctic operator and has an active role in Antarctic affairs Nature Geoscience is a Scientific journal published by Nature Publishing Group, publisher of the flagship journal Nature. The biggest eruption in the last 10,000 years, the volcanic ash was found deposited on the ice surface under the Hudson Mountains, close to Pine Island Glacier. The Hudson Mountains is a group of parasitic cones forming Nunataks just above the Antarctic ice sheet in west Ellsworth Land. Pine Island Glacier is a broad Glacier flowing west-northwest along the south side of the Hudson Mountains into Pine Island Bay, Amundsen Sea ^[1]

Mud volcanoes

Main article: Mud volcano

The term mud volcano (mud dome, or mud pot) is used to refer to formations created by geo-excreted liquids and gases, although there are several different processes which may cause such activity. Note See the Volcano article for information on Magmatic volcanoes such as Mount St Note See the Volcano article for information on Magmatic volcanoes such as Mount St The largest structures are 10 km in diameter and reach 700 metres in height.

Erupted material

Lava composition

Pāhoehoe Lava flow at Hawaii (island). Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures The Island of Hawaii, also called the Big Island or Hawaii Island, is a volcanic Island in the U The picture shows few overflows of a main lava channel. Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures

Another way of classifying volcanoes is by the composition of material erupted (lava), since this affects the shape of the volcano. Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures Lava can be broadly classified into 4 different compositions (Cas & Wright, 1987):

• If the erupted magma contains a high percentage (>63%) of silica, the lava is called felsic. Magma (Plurals magmas and magmata) is molten rock that sometimes forms beneath the surface of the Earth (or any other Terrestrial planet The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide Felsic is a term used in Geology to refer to Silicate minerals, Magma, and rocks which are enriched in the lighter elements such as Silicon
  • Felsic lavas (or rhyolites) tend to be highly viscous (not very fluid) and are erupted as domes or short, stubby flows. This page is about a volcanic rock For the ghost town see Rhyolite Nevada, and for the satellite system see Rhyolite/Aquacade. Viscosity is a measure of the resistance of a Fluid which is being deformed by either Shear stress or Extensional stress. Viscous lavas tend to form stratovolcanoes or lava domes. A stratovolcano, also called a composite volcano is a tall conical Volcano composed of many layers of hardened Lava, Tephra, and Volcanic In Volcanology, a lava dome or plug dome is a roughly circular Mound -shaped protrusion resulting from the slow eruption of Felsic Lava Lassen Peak in California is an example of a volcano formed from felsic lava and is actually a large lava dome. Lassen Peak (also known as Mount Lassen) is the southernmost active Volcano in the Cascade Range. California ( is a US state on the West Coast of the United States, along the Pacific Ocean.
  • Because siliceous magmas are so viscous, they tend to trap volatiles (gases) that are present, which cause the magma to erupt catastrophically, eventually forming stratovolcanoes. In Planetary science, volatiles, are that group of elements and compounds with low boiling points (see volatile) that are associated with a planet's or moon's A stratovolcano, also called a composite volcano is a tall conical Volcano composed of many layers of hardened Lava, Tephra, and Volcanic Pyroclastic flows (ignimbrites) are highly hazardous products of such volcanoes, since they are composed of molten volcanic ash too heavy to go up into the atmosphere, so they hug the volcano's slopes and travel far from their vents during large eruptions. A pyroclastic flow (also known as a pyroclastic density current) is a common and devastating result of some volcanic eruptions. Ignimbrite is a Volcanic Pyroclastic rock often of Dacitic or Rhyolitic composition Temperatures as high as 1,200 °C are known to occur in pyroclastic flows, which will incinerate everything flammable in their path and thick layers of hot pyroclastic flow deposits can be laid down, often up to many meters thick. A pyroclastic flow (also known as a pyroclastic density current) is a common and devastating result of some volcanic eruptions. Alaska's Valley of Ten Thousand Smokes, formed by the eruption of Novarupta near Katmai in 1912, is an example of a thick pyroclastic flow or ignimbrite deposit. Alaska ( Аляска Alyaska) is a state in the United States of America, in the northwest of the North American continent 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 Novarupta, meaning "new eruption" is a Volcano located on the Alaska Peninsula in the Katmai, about southwest of Anchorage. A pyroclastic flow (also known as a pyroclastic density current) is a common and devastating result of some volcanic eruptions. Ignimbrite is a Volcanic Pyroclastic rock often of Dacitic or Rhyolitic composition Volcanic ash that is light enough to be erupted high into the Earth's atmosphere may travel many kilometres before it falls back to ground as a tuff. Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five Tuff (from the Italian "tufo" is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption
• If the erupted magma contains 52–63% silica, the lava is of intermediate composition.
  • These "andesitic" volcanoes generally only occur above subduction zones (e. For the extinct cephalopod genus see Andesites. Andesite (ˈændəsaɪt is an igneous, Volcanic rock, of intermediate In Geology, a subduction zone is an area on Earth where two tectonic plates meet and move towards one another with one sliding underneath the other g. Mount Merapi in Indonesia). Mount Merapi, Gunung Merapi in Indonesian language, is a conical Volcano located on the border between Central Java and Yogyakarta The Republic of Indonesia ( (Republik Indonesia is a Country in Southeast Asia.
• If the erupted magma contains <52% and >45% silica, the lava is called mafic (because it contains higher percentages of magnesium (Mg) and iron (Fe)) or basaltic. Mafic is an adjective describing a Silicate mineral or rock that is rich in magnesium and iron the term was derived by contracting "magnesium" and "ferric" Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24 Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Basalt (bəˈsɔːlt ˈbeisɔːlt ˈbæsɔːlt is a common Extrusive Volcanic rock. These lavas are usually much less viscous than rhyolitic lavas, depending on their eruption temperature; they also tend to be hotter than felsic lavas. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Mafic lavas occur in a wide range of settings:
  • At mid-ocean ridges, where two oceanic plates are pulling apart, basaltic lava erupts as pillows to fill the gap;
  • Shield volcanoes (e. A mid-ocean ridge or mid-oceanic ridge is an underwater Mountain range typically having a valley known as a Rift running along its axis formed by Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures A shield volcano is a large Volcano with shallow-sloping sides g. the Hawaiian Islands, including Mauna Loa and Kilauea), on both oceanic and continental crust;
  • As continental flood basalts. The Hawaiian Islands, once known as the Sandwich Islands, form an Archipelago of 19 Islands and Atolls numerous smaller Mauna Loa is the largest volcano on earth and one of five volcanoes that form the Island of Hawaii in the U Kīlauea (kiːlauea is an active Volcano in the Hawaiian Islands, one of five Shield volcanoes that together form the Island of Hawai{{okina}}i Oceanic crust is the part of Earth's Lithosphere that surfaces in the Ocean basins The continental crust is the layer of granitic, Sedimentary, and Metamorphic rocks which form the Continents and the areas of shallow seabed A flood basalt or trap basalt is the result of a giant Volcanic eruption or series of Eruptions that coats large stretches of land or the Ocean floor
• Some erupted magmas contain <=45% silica and produce ultramafic lava. Ultramafic (also referred to as ultrabasic) rocks are igneous and meta -igneous rocks with very low Silica content (less than 45% generally Ultramafic flows, also known as komatiites, are very rare; indeed, very few have been erupted at the Earth's surface since the Proterozoic, when the planet's heat flow was higher. Komatiites are Ultramafic mantle-derived Volcanic rocks They have low SiO2 low K2O low Al2O3 and high to extremely high The Proterozoic (ˌproʊtərəˈzoʊɪk is a geological eon representing a period before the first abundant complex life on Earth. They are (or were) the hottest lavas, and probably more fluid than common mafic lavas.

Lava texture

Two types of lava are named according to the surface texture: ʻAʻa (pronounced [ʔaʔa]) and pāhoehoe (pronounced IPA: [[Help:IPA|paːhoehoe]]), both words having Hawaiian origins. In Mathematics, specifically in Topology, a surface is a Two-dimensional Manifold. Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures The Hawaiian language (Hawaiian ‘Ōlelo Hawai‘i) is an Austronesian language that takes its name from Hawai'i, the largest island in the tropical ʻAʻa is characterized by a rough, clinkery surface and is what most viscous and hot lava flows look like. However, even basaltic or mafic flows can be erupted as ʻaʻa flows, particularly if the eruption rate is high and the slope is steep. Pāhoehoe is characterized by its smooth and often ropey or wrinkly surface and is generally formed from more fluid lava flows. Usually, only mafic flows will erupt as pāhoehoe, since they often erupt at higher temperatures or have the proper chemical make-up to allow them to flow at a higher fluidity.

Volcanic activity

A volcanic fissure and lava channel

Mount St. Helens in May 1980, shortly after the eruption of May 18

A popular way of classifying magmatic volcanoes is by their frequency of eruption, with those that erupt regularly called active, those that have erupted in historical times but are now quiet called dormant, and those that have not erupted in historical times called extinct. A fissure vent, also known as a volcanic fissure or simply fissure, is a linear Volcanic vent through which Lava erupts usually without any Mount St Helens is an active Stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States The 1980 eruption of Mount St Helens, a volcano located in Washington state in the United States was a major volcanic eruption. However, these popular classifications—extinct in particular—are practically meaningless to scientists. They use classifications which refer to a particular volcano's formative and eruptive processes and resulting shapes, which was explained above.

There is no real consensus among volcanologists on how to define an "active" volcano. The lifespan of a volcano can vary from months to several million years, making such a distinction sometimes meaningless when compared to the lifespans of humans or even civilizations. For example, many of Earth's volcanoes have erupted dozens of times in the past few thousand years but are not currently showing signs of eruption. Given the long lifespan of such volcanoes, they are very active. By human lifespans, however, they are not.

Scientists usually consider a volcano to be active if it is currently erupting or showing signs of unrest, such as unusual earthquake activity or significant new gas emissions. Many scientists also consider a volcano active if it has erupted in historic time. It is important to note that the span of recorded history differs from region to region; in the Mediterranean, recorded history reaches back more than 3,000 years but in the Pacific Northwest of the United States, it reaches back less than 300 years, and in Hawaii, little more than 200 years. The State of Hawaii ( or həˈwaɪʔiː Hawaiian: Mokuāina o Hawaii) is a state in the United States located on an Archipelago in the The Smithsonian Global Volcanism Program's definition of 'active' is having erupted within the last 10,000 years.

Dormant volcanoes are those that are not currently active (as defined above), but could become restless or erupt again. Confusion however, can arise because many volcanoes which scientists consider to be active are referred to as dormant by laypersons or in the media.

Extinct volcanoes are those that scientists consider unlikely to erupt again, because the volcano no longer has a lava supply anymore. Examples of extinct volcanoes are many volcanoes on the Hawaiian Islands in the U.S. (extinct because the Hawaii hotspot is centered near the Big Island), and Paricutin, which is monogenetic. The Hawaiian Islands, once known as the Sandwich Islands, form an Archipelago of 19 Islands and Atolls numerous smaller The United States of America —commonly referred to as the The Hawaii hotspot is perhaps the best known volcanic hotspot on Earth, responsible for the Hawaiian Islands in the Pacific Ocean. Parícutin (or Volcán de Parícutin also accented Paricutín by locals to more closely match the pronunciation of the native Purepecha name Parhicutini or spelled unaccented A monogenetic volcanic field is a Volcanic field of small scattered volcanic vents Otherwise, whether a volcano is truly extinct is often difficult to determine. Since "supervolcano" calderas can have eruptive lifespans sometimes measured in millions of years, a caldera that has not produced an eruption in tens of thousands of years is likely to be considered dormant instead of extinct. A caldera is a cauldron-like volcanic feature formed by the collapse of land following a volcanic eruption For example, the Yellowstone Caldera in Yellowstone National Park is at least 2 million years old and hasn't erupted violently for approximately 640,000 years, although there has been some minor activity relatively recently, with hydrothermal eruptions less than 10,000 years ago and lava flows about 70,000 years ago. The Yellowstone Caldera is the volcanic Caldera in Yellowstone National Park in the United States. For this reason, scientists do not consider the Yellowstone Caldera extinct. In fact, because the caldera has frequent earthquakes, a very active geothermal system (i. e. the entirety of the geothermal activity found in Yellowstone National Park), and rapid rates of ground uplift, many scientists consider it to be an active volcano.

Notable volcanoes

Main article: List of volcanoes

The 16 current Decade Volcanoes are:

Avachinsky-Koryaksky, Kamchatka, Russia Colima, Jalisco and Colima, Mexico Mount Etna, Sicily, Italy Galeras, Nariño, Colombia Mauna Loa, Hawaii, USA Mount Merapi, Central Java, Indonesia Mount Nyiragongo, Democratic Republic of the Congo Mount Rainier, Washington, USA

Sakurajima, Kagoshima Prefecture, Japan Santamaria/Santiaguito, Guatemala Santorini, Cyclades, Greece Taal Volcano, Luzon, Philippines Teide, Canary Islands, Spain Ulawun, New Britain, Papua New Guinea Mount Unzen, Nagasaki Prefecture, Japan Vesuvius, Naples, Italy

Effects of volcanoes

Volcanic "injection"

Solar radiation reduction from volcanic eruptions

Sulfur dioxide emissions by volcanoes. This is a list of lists of active and extinct Volcanoes sorted by country The Decade Volcanoes are 16 Volcanoes identified by the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI as being worthy Avachinsky (also known as Avacha or Avacha Volcano or Avachinskaya Sopka) (Авачинская сопка Авача is an active Stratovolcano Koryaksky or Koryakskaya Sopka (Коря́кская со́пка is a Russia (Россия Rossiya) or the Russian Federation ( Rossiyskaya Federatsiya) is a transcontinental Country extending Colima's Volcano is the most active Volcano in Mexico, and has erupted more than 40 times since 1576. Jalisco is a state in Mexico. The capital of Jalisco is the city of Guadalajara. For the state capital of the same name see Colima Colima. There is also a volcano named Colima, and a spider genus Colima ( Zodariidae The United Mexican States ( or commonly Mexico (ˈmɛksɪkoʊ () is a federal constitutional Republic in North America. Sicily ( Italian and Sicilian: Sicilia) is an autonomous region of Italy. Italy (Italia officially the Italian Republic, (Repubblica Italiana is located on the Italian Peninsula in Southern Europe, and on the two largest Galeras ( Urcunina among the XVI century indigenous people is an active Stratovolcano in Colombia, near the city of Pasto. Colombia (kəˈlʌmbɪə officially the Republic of Colombia () is a country in northwestern South America. Mauna Loa is the largest volcano on earth and one of five volcanoes that form the Island of Hawaii in the U The State of Hawaii ( or həˈwaɪʔiː Hawaiian: Mokuāina o Hawaii) is a state in the United States located on an Archipelago in the The United States of America —commonly referred to as the Mount Merapi, Gunung Merapi in Indonesian language, is a conical Volcano located on the border between Central Java and Yogyakarta Central Java ( Provinsi Jawa Tengah) is a province of Indonesia. The Republic of Indonesia ( (Republik Indonesia is a Country in Southeast Asia. Mount Nyiragongo is a Stratovolcano in the Virunga Mountains associated with the Great Rift Valley. The Democratic Republic of the Congo (République démocratique du Congo often referred to as DR Congo, DRC or RDC, and formerly known or referred to Mount Rainier is an active Stratovolcano (also known as a composite volcano in Pierce County Washington, located southeast of Seattle, Washington Washington ( is a state in the Pacific Northwest region of the United States. The United States of America —commonly referred to as the is an active Volcano and a former island (now connected to the mainland of the same name in Kagoshima Prefecture in Kyūshū, Japan. WikipediaWikiProject Japanese prefectures for guidelines --> is a prefecture of Japan located on Kyūshū Island. For a topic outline on this subject see List of basic Japan topics. Volcán Santa María is a large active Volcano in the Western Highlands of Guatemala, close to the city of Quetzaltenango. Guatemala (República de Guatemala) is a country in Central America bordered by Mexico to the north and west the Pacific Ocean to the southwest The CYCLADES Packet switching network was an extremely influential French network system in the early 1970s similar to the ARPANET. Greece (Ελλάδα transliterated: Elláda, historically, Ellás,) officially the Hellenic Republic (Ελληνική Δημοκρατία Taal Volcano is an active Volcano on the island of Luzon in the Philippines. Luzon is the largest and most economically and politically important Island in the Philippines and one of the three island groups in the country with Visayas The Philippines ( Filipino: Pilipinas, officially known as the Republic of the Philippines (fil ''Republika ng Pilipinas'' RP Mount Teide or in Spanish El Teide, is an active though dormant Volcano which last erupted in 1909 from the El Chinyero vent on the Santiago (northwestern rift The Canary Islands ( English pronunciation kəˈnæriː ˈaɪləndz Spanish: Islas Canarias, ˈizlas kaˈnarjas are a Spanish Spain () or the Kingdom of Spain (Reino de España is a country located mostly in southwestern Europe on the Iberian Peninsula. Ulawun is a Volcano situated on the island of New Britain, Papua New Guinea, about 130 km southwest of Rabaul. This article discusses the island of New Britain in Papua New Guinea Papua New Guinea (or ˈpæpjuːə in Tok Pisin: Papua Niugini) officially the Independent State of Papua New Guinea, is a country in Oceania Mount Unzen ( jp 雲仙岳 Unzendake) is an active volcanic complex of several overlapping Stratovolcanoes also known as a Composite volcano WikipediaWikiProject Japanese prefectures for guidelines --> is a prefecture of Japan located on the island of Kyūshū. For a topic outline on this subject see List of basic Japan topics. Mount Vesuvius (in Italian Monte Vesuvio and in Latin Mons Vesuvius) is an active Stratovolcano east of Naples The Province of Naples ( Italian: Provincia di Napoli, Nnapulitano: Pruvincia 'e Nàpule) is a province in the Campania Italy (Italia officially the Italian Republic, (Repubblica Italiana is located on the Italian Peninsula in Southern Europe, and on the two largest

Average concentration of sulfur dioxide over the Sierra Negra Volcano (Galapagos Islands) from October 23–November 1, 2005

There are many different kinds of volcanic activity and eruptions: phreatic eruptions (steam-generated eruptions), explosive eruption of high-silica lava (e. A Phreatic eruption, also called an ultravulcanian eruption, occurs when rising Magma makes contact with ground or surface water The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures g. , rhyolite), effusive eruption of low-silica lava (e. This page is about a volcanic rock For the ghost town see Rhyolite Nevada, and for the satellite system see Rhyolite/Aquacade. g. , basalt), pyroclastic flows, lahars (debris flow) and carbon dioxide emission. Basalt (bəˈsɔːlt ˈbeisɔːlt ˈbæsɔːlt is a common Extrusive Volcanic rock. A pyroclastic flow (also known as a pyroclastic density current) is a common and devastating result of some volcanic eruptions. A lahar is a type of Mudflow / Landslide composed of Pyroclastic material and Water that flows down from a Volcano, typically Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single All of these activities can pose a hazard to humans. Earthquakes, hot springs, fumaroles, mud pots and geysers often accompany volcanic activity. An earthquake is the result of a sudden release of energy in the Earth 's crust that creates Seismic waves Earthquakes are recorded with a Seismometer A hot spring is a spring that is produced by the emergence of geothermally heated Groundwater from the earth's crust. A geyser is a Hot spring characterized by intermittent discharge of water ejected turbulently and accomplished by a vapour phase

The concentrations of different volcanic gases can vary considerably from one volcano to the next. Volcanic gases include a variety of substances given off by active (or at times by dormant Volcanoes These include gases trapped in cavities ( Vesicles) in Water vapor is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide. General properties of water vapor Evaporation/sublimation Whenever a water molecule leaves a surface it is said to have evaporated Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Other principal volcanic gases include hydrogen sulfide, hydrogen chloride, and hydrogen fluoride. Hydrogen sulfide (or hydrogen sulphide) is the Chemical compound with the formula H 2 S. Structure HF forms orthorhombic crystals consisting of zig-zag chains of HF molecules A large number of minor and trace gases are also found in volcanic emissions, for example hydrogen, carbon monoxide, halocarbons, organic compounds, and volatile metal chlorides. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Carbon monoxide, with the chemical formula CO is a colorless odorless tasteless yet highly toxic Gas. Halocarbon compounds are Chemicals in which one or more Carbon Atoms are linked by Covalent bonds with one or more Halogen Atoms

Large, explosive volcanic eruptions inject water vapor (H₂O), carbon dioxide (CO₂), sulfur dioxide (SO₂), hydrogen chloride (HCl), hydrogen fluoride (HF) and ash (pulverized rock and pumice) into the stratosphere to heights of 16–32 kilometres (10–20 mi) above the Earth's surface. Pumice is a textural term for a volcanic rock that is a solidified frothy lava composed of highly microvesicular glass Pyroclastic with very thin translucent The stratosphere is the second major layer of Earth's atmosphere, just above the Troposphere, and below the Mesosphere. The most significant impacts from these injections come from the conversion of sulfur dioxide to sulfuric acid (H₂SO₄), which condenses rapidly in the stratosphere to form fine sulfate aerosols. Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid. Particulates, alternatively referred to as particulate matter (PM or fine particles, are tiny particles of solid or liquid suspended in a gas The aerosols increase the Earth's albedo—its reflection of radiation from the Sun back into space - and thus cool the Earth's lower atmosphere or troposphere; however, they also absorb heat radiated up from the Earth, thereby warming the stratosphere. The albedo of an object is the extent to which it diffusely reflects light from the sun The Sun (Sol is the Star at the center of the Solar System. The stratosphere is the second major layer of Earth's atmosphere, just above the Troposphere, and below the Mesosphere. Several eruptions during the past century have caused a decline in the average temperature at the Earth's surface of up to half a degree (Fahrenheit scale) for periods of one to three years. The sulfate aerosols also promote complex chemical reactions on their surfaces that alter chlorine and nitrogen chemical species in the stratosphere. A chemical substance is a Material with a definite chemical composition. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 This effect, together with increased stratospheric chlorine levels from chlorofluorocarbon pollution, generates chlorine monoxide (ClO), which destroys ozone (O₃). Chlorine (ˈklɔriːn from the Greek word 'χλωρóς' ( khlôros, meaning 'pale green' is the Chemical element with Atomic number 17 and The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane OZONE is an object oriented Operating system written in the C programming language. As the aerosols grow and coagulate, they settle down into the upper troposphere where they serve as nuclei for cirrus clouds and further modify the Earth's radiation balance. Cirrus clouds are characterized by thin wisplike strands often accompanied by tufts leading to their common (non-standard name of 'mare's tail' Radiation, as in Physics, is Energy in the form of waves or moving Subatomic particles emitted by an atom or other body as it changes from a higher energy Most of the hydrogen chloride (HCl) and hydrogen fluoride (HF) are dissolved in water droplets in the eruption cloud and quickly fall to the ground as acid rain. Acid rain is Rain or any other form of precipitation that is unusually Acidic It has harmful effects on plants aquatic animals and infastructure The injected ash also falls rapidly from the stratosphere; most of it is removed within several days to a few weeks. Finally, explosive volcanic eruptions release the greenhouse gas carbon dioxide and thus provide a deep source of carbon for biogeochemical cycles. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6

Rainbow and volcanic ash with sulfur dioxide emissions from Halema`uma`u vent. A rainbow is an optical and meteorological phenomenon that causes a spectrum of Light to appear in the Sky when the Sun Volcanic ash consists of small Tephra, which are bits of pulverized rock and glass created by volcanic eruptions less than in diameter

Gas emissions from volcanoes are a natural contributor to acid rain. Acid rain is Rain or any other form of precipitation that is unusually Acidic It has harmful effects on plants aquatic animals and infastructure Volcanic activity releases about 130 to 230 teragrams (145 million to 255 million short tons) of carbon dioxide each year. The short ton ( S/T) is a unit of mass equal to 2000 lb (around 907 Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single ^[2] Volcanic eruptions may inject aerosols into the Earth's atmosphere. Particulates, alternatively referred to as particulate matter (PM or fine particles, are tiny particles of solid or liquid suspended in a gas Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five Large injections may cause visual effects such as unusually colorful sunsets and affect global climate mainly by cooling it. Climate encompasses the temperatures humidity rainfall atmospheric particle count and numerous other meteorogical factors in a given region over long periods of Volcanic eruptions also provide the benefit of adding nutrients to soil through the weathering process of volcanic rocks. Soil, often typeset as SOiL, is a four piece rock band from Chicago Illinois United States founded by Shaun Glass Tom Schofield Tim King and Adam Zadel Weathering is the decomposition of earth rocks, Soils and their Minerals through direct contact with the planet's Atmosphere. These fertile soils assist the growth of plants and various crops. Volcanic eruptions can also create new islands, as the magma cools and solidifies upon contact with the water.

Volcanoes on other planetary bodies

Olympus Mons (Latin, "Mount Olympus") is the tallest known mountain in our solar system, located on the planet Mars. Olympus Mons ( Latin for "Mount Olympus" is the highest known Volcano and Mountain in the Solar System. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. A mountain is a Landform that extends above the surrounding Terrain in a limited area with a peak The Solar System consists of the Sun and those celestial objects bound to it by Gravity. A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is

Main articles: Geology of the Moon, Geology of Mars, Volcanism on Io, and Volcanism on Venus

The Earth's Moon has no large volcanoes and no current volcanic activity, although recent evidence suggests it may still possess a partially molten core. The geology of the Moon (sometimes called selenology, although the latter term can refer more generally to "lunar The geology of Mars, also known as areology (from Greek grc Ἂρης Arēs, " Ares " and grc -λογία -logia This is a sub-article to Io (moon Volcanism on Io, a moon of Jupiter, produces Lava flows volcanic pits and plumes The surface of Venus is dominated by volcanism and has produced more volcanoes than any other Planet in the Solar system. ^[3] However, the Moon does have many volcanic features such as maria (the darker patches seen on the moon), rilles and domes. The lunar maria (singular mare, two syllables are large dark Basaltic plains on Earth 's Moon, formed by ancient Volcanic eruptions Rille (German for 'groove' is typically used to describe any of the long narrow depressions in the lunar surface that resemble channels. A lunar dome is a type of Shield volcano that is found on the surface of the Earth 's Moon.

The planet Venus has a surface that is 90% basalt, indicating that volcanism played a major role in shaping its surface. The VENUS ( V ictoria E xperimental N etwork U nder the S ea project is a cabled sea floor observatory operated by the University Basalt (bəˈsɔːlt ˈbeisɔːlt ˈbæsɔːlt is a common Extrusive Volcanic rock. The planet may have had a major global resurfacing event about 500 million years ago,^[4] from what scientists can tell from the density of impact craters on the surface. Lava flows are widespread and forms of volcanism not present on Earth occur as well. Changes in the planet's atmosphere and observations of lightning, have been attributed to ongoing volcanic eruptions, although there is no confirmation of whether or not Venus is still volcanically active. However, radar sounding by the Magellan probe revealed evidence for comparatively recent volcanic activity at Venus's highest volcano Maat Mons, in the form of ash flows near the summit and on the northern flank. Maat Mons is the highest volcano on the Planet Venus. The Volcano is above the mean planetary radius and is found at 0

There are several extinct volcanoes on Mars, four of which are vast shield volcanoes far bigger than any on Earth. They include Arsia Mons, Ascraeus Mons, Hecates Tholus, Olympus Mons, and Pavonis Mons. Arsia Mons is the southernmost of three Volcanos (collectively known as Tharsis Montes) on the Tharsis bulge near the Equator of the Planet Ascraeus Mons is the northernmost of three Volcanos (collectively known as Tharsis Montes) on the Tharsis bulge near the Equator of the Planet Hecates Tholus is a Martian Volcano, notable for results from the European Space Agency 's Mars Express mission which indicate a major eruption Olympus Mons ( Latin for "Mount Olympus" is the highest known Volcano and Mountain in the Solar System. Pavonis Mons is the middle of three Volcanos (collectively known as Tharsis Montes) on the Tharsis bulge near the Equator of the Planet These volcanoes have been extinct for many millions of years,^[5] but the European Mars Express spacecraft has found evidence that volcanic activity may have occurred on Mars in the recent past as well. Mars Express is a Space exploration mission being conducted by the European Space Agency (ESA ^[5]

The Tvashtar volcano erupts a plume 330 km (205 mi) above the surface of Jupiter's moon Io. Tvashtar Paterae compose an active volcanic region of Jupiter 's moon Io located near the moon's north pole TemplateInfobox Planet.--> Io (ˈaɪoʊ, or as Greek

Jupiter's moon Io is the most volcanically active object in the solar system because of tidal interaction with Jupiter. A natural satellite or moon is a Celestial body that Orbits a Planet or smaller body which is called the primary. TemplateInfobox Planet.--> Io (ˈaɪoʊ, or as Greek Characteristics A tide is a repeated cycle of sea level changes in the following stages Over several hours the water rises or advances up a beach in the flood It is covered with volcanoes that erupt sulfur, sulfur dioxide and silicate rock, and as a result, Io is constantly being resurfaced. Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 For the Artificial intelligence Androids of the 1990s Science fiction series Space Above and Beyond, see Silicate (AI TemplateInfobox Planet.--> Io (ˈaɪoʊ, or as Greek Its lavas are the hottest known anywhere in the solar system, with temperatures exceeding 1,800 K (1,500 °C). In February 2001, the largest recorded volcanic eruptions in the solar system occurred on Io. ^[6] Europa, the smallest of Jupiter's Galilean moons, also appears to have an active volcanic system, except that its volcanic activity is entirely in the form of water, which freezes into ice on the frigid surface. TemplateInfobox Planet.--> Europa (jʊˈroʊpə; or as The Galilean moons are the four moons of Jupiter discovered by Galileo Galilei. This process is known as cryovolcanism, and is apparently most common on the moons of the outer planets of the solar system. A cryovolcano is literally an Icy Volcano. Cryovolcanoes form on Icy moons and possibly on other low- Temperature Astronomical objects The Solar System consists of the Sun and those celestial objects bound to it by Gravity.

In 1989 the Voyager 2 spacecraft observed cryovolcanoes (ice volcanoes) on Triton, a moon of Neptune, and in 2005 the Cassini-Huygens probe photographed fountains of frozen particles erupting from Enceladus, a moon of Saturn. Voyager 2 is an unmanned Interplanetary Spacecraft launched on August 20, 1977. A cryovolcano is literally an Icy Volcano. Cryovolcanoes form on Icy moons and possibly on other low- Temperature Astronomical objects TemplateInfobox Planet.--> Triton (ˈtraɪtən, or as in Greek A natural satellite or moon is a Celestial body that Orbits a Planet or smaller body which is called the primary. Neptune ( English|AmE] ] is the eighth and farthest Planet from the Sun in the Solar System. Cassini–Huygens is a joint NASA / ESA / ASI Robotic spacecraft mission currently studying the planet Saturn and its TemplateInfobox Planet.--> This article is about the moon of ^[7] The ejecta may be composed of water, liquid nitrogen, dust, or methane compounds. Water is a common Chemical substance that is essential for the survival of all known forms of Life. Liquid nitrogen (liquid density at the Triple point is 0707 g/mL is the liquid produced industrially in large quantities by Fractional distillation of Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. Cassini-Huygens also found evidence of a methane-spewing cryovolcano on the Saturnian moon Titan, which is believed to be a significant source of the methane found in its atmosphere. TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as ^[8] It is theorized that cryovolcanism may also be present on the Kuiper Belt Object Quaoar. The Kuiper belt (ˈkaɪpɚ to rhyme with "viper" sometimes called the Edgeworth-Kuiper belt, is a region of the Solar System beyond the planets extending

Etymology

Volcano is thought to derive from Vulcano, a volcanic island in the Aeolian Islands of Italy whose name in turn originates from Vulcan, the name of a god of fire in Roman mythology. Vulcano is a small volcanic island ( in the Tyrrhenian Sea, about 25 km north of Sicily and the southernmost of the Aeolian Islands. The Aeolian Islands ( Italian Isole Eolie) are a Volcanic Archipelago in the Tyrrhenian Sea north of Sicily. Italy (Italia officially the Italian Republic, (Repubblica Italiana is located on the Italian Peninsula in Southern Europe, and on the two largest In ancient Roman religion and Hellenic neopaganism, Vulcan is the god of beneficial and hindering fire including the fire of Volcanoes He is also Fire is the heat and light energy released during a Chemical reaction, in particular a combustion reaction. Roman mythology, or more appropriately Latin mythology, refers to the mythological beliefs of the Italic people inhabiting the region of Latium and its The study of volcanoes is called volcanology, sometimes spelled vulcanology. Volcanology (also spelled vulcanology) is the study of Volcanoes, Lava, Magma, and related geological and Geophysical phenomena

The Roman name for the island Vulcano has contributed the word for volcano in most modern European languages. Vulcano is a small volcanic island ( in the Tyrrhenian Sea, about 25 km north of Sicily and the southernmost of the Aeolian Islands.

In culture

Past beliefs

Kircher's model of the Earth's internal fires, from Mundus Subterraneus

Many ancient accounts ascribe volcanic eruptions to supernatural causes, such as the actions of gods or demigods. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 The term supernatural or supranatural ( Latin: super, supra "above" + natura "nature" pertains to entities events See also List of deities A deity is a Postulated Preternatural or Supernatural Being, who is always The term " demigod " meaning "half-god" is used to describe mythological figures whose one parent was a god and whose other parent was human To the ancient Greeks, volcanoes' capricious power could only be explained as acts of the gods, while 16th/17th-century German astronomer Johannes Kepler believed they were ducts for the Earth's tears. ^[9] One early idea counter to this was proposed by Jesuit Athanasius Kircher (1602–1680), who witnessed eruptions of Mount Etna and Stromboli, then visited the crater of Vesuvius and published his view of an Earth with a central fire connected to numerous others caused by the burning of sulfur, bitumen and coal. The Society of Jesus ( Latin: Societas Iesu, SJ and SI or SJ, SI) is a Catholic religious order Athanasius Kircher (sometimes erroneously spelled Kirchner) was a 17th century German Jesuit Scholar who published around 40 works most Stromboli (Strongyle is a small island in the Tyrrhenian Sea, off the north coast of Sicily, containing one of the three active volcanoes in Italy Mount Vesuvius (in Italian Monte Vesuvio and in Latin Mons Vesuvius) is an active Stratovolcano east of Naples Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Bitumen is a mixture of organic Liquids that are highly Viscous, black sticky entirely soluble in Carbon disulfide, and composed primarily

Various explanations were proposed for volcano behavior before the modern understanding of the Earth's mantle structure as a semisolid material was developed. The mantle is a part of an Astronomical object. The interior of the Earth, similar to the other Terrestrial planets, is Chemically divided For decades after awareness that compression and radioactive materials may be heat sources, their contributions were specifically discounted. Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. Volcanic action was often attributed to chemical reactions and a thin layer of molten rock near the surface. A chemical substance is a Material with a definite chemical composition.

Heraldry

Volcanoes appear as a charge in heraldry. In Heraldry and Vexillology, a charge is an image occupying the field on an escutcheon (or shield Heraldry in its most general sense encompasses all matters relating to the duties and responsibilities of officers of arms.

Panoramas

Irazú Volcano, Costa Rica

See also

• History of Volcanology
• Plinian eruption
• Types of volcanic eruptions
• Prediction of volcanic activity
• Volcano observatory
• Geomorphology
• Earth science
• Volcanic field
• Volcanic gas
• Tsunami

Lists

• List of volcanoes (terrestrial)
• List of extraterrestrial volcanoes
• List of famous volcanic eruption deaths
• Volcanic Explosivity Index (includes list of large eruptions)
• Types of volcanic eruptions
• List of deadliest natural disasters

Specific locations

• Iceland hotspot
• Anahim hotspot
• Kerguelen hotspot
• East Australia hotspot
• Hawaii hotspot
• Bowie hotspot
• Réunion hotspot
• Galápagos hotspot
• New England hotspot
• Canary hotspot
• Pacific Ring of Fire
• Io (moon)
• Triton (moon)

People

• Category:Volcanologists

Further reading

• Marti, Joan and Ernst, Gerald. The Irazú Volcano ( Volcán Irazú) is an Active volcano in Costa Rica, situated in the Cordillera Central close to the city of Cartago Volcanology (also spelled vulcanology) is the study of Volcanoes, Lava, Magma, and related geological and Geophysical phenomena Plinian eruptions are Volcanic eruptions marked by their similarity to the eruption of Mt Prediction of volcanic activity (also volcanic eruption forecasting) is an interdisciplinary scientific and engineering approach to natural catastrophic event forecasting A volcano observatory is an institution that conducts research and monitoring of a Volcano. Geomorphology (from Greek: γη ge, "earth" μορφή morfé, "form" and λόγος Logos, "knowledge" Earth science (also known as geoscience, the geosciences or the Earth Sciences) is an all-embracing term for the Sciences related to the planet A volcanic field is a spot of the Earth 's crust that is prone to localized Volcanic activity Volcanic gases include a variety of substances given off by active (or at times by dormant Volcanoes These include gases trapped in cavities ( Vesicles) in A tsunami ((tsuːˈnɑːmi is a series of waves created when This is a list of lists of active and extinct Volcanoes sorted by country This is a list of active dormant and extinct Volcanoes located beyond planet Earth. See also Lists of people by cause of death Volcano The Volcanic Explosivity Index (VEI was devised by Chris Newhall of the U For man-made disasters see List of wars and disasters by death toll A death toll is the number of dead as a result of War, Violence, The Iceland hotspot is a hotspot which is partly responsible for the high volcanic activity which has formed the island of Iceland. The Anahim hotspot is a volcanic hotspot in central British Columbia, Canada. The Kerguelen hotspot is a Volcanic hotspot at the Kerguelen Plateau in the Southern Indian Ocean. The East Australia hotspot is a volcanic hotspot that takes advantage of weak spots in the Indo-Australian Plate to feed Magma to the Volcanoes The Hawaii hotspot is perhaps the best known volcanic hotspot on Earth, responsible for the Hawaiian Islands in the Pacific Ocean. The Bowie hotspot is a volcanic hotspot, located 180 kilometers west of the Queen Charlotte Islands in the Pacific Ocean. The Réunion hotspot is a Volcanic hotspot which currently lies under the Island of Réunion in the Indian Ocean. Galápagos hotspot is a volcanic hotspot responsible for the formation of the Galápagos Islands in the Pacific Ocean. The New England hotspot, also referred to as the Great Meteor hotspot, is a long-lived volcanic hotspot in the Atlantic Ocean. The Canary hotspot is a volcanic hotspot believed to be located at the Canary Islands off the north-western coast of Africa, although alternative TemplateInfobox Planet.--> Io (ˈaɪoʊ, or as Greek TemplateInfobox Planet.--> Triton (ˈtraɪtən, or as in Greek (2005). Volcanoes and the Environment. Cambridge University Press. ISBN 0-521-59254-2.  
• Macdonald, Gordon A. , and Agatin T. Abbott. (1970). Volcanoes in the Sea. University of Hawaii Press, Honolulu. 441 p.
• Ollier, Cliff. (1988). Volcanoes. Basil Blackwell, Oxford, UK, ISBN 0-631-15664-X (hardback), ISBN 0-631-15977-0 (paperback).
• Haraldur Sigurðsson, ed. Haraldur Sigurdsson was born May 31, 1939 (1999) Encyclopedia of Volcanoes. Academic Press. ISBN 0-12-643140-X. This is a reference aimed at geologists, but many articles are accessible to non-professionals.
• Cas, R. A. F. and J. V. Wright, 1987. Volcanic Successions. Unwin Hyman Inc. 528p. ISBN 0-04-552022-4

Notes

External links

• How to survive a volcanic eruption - A guide for children and youth
• Smithsonian Institution - Global Volcanism Program
• Volcanic and Geologic Terms from Volcano World
• Volcano Information from the Deep Ocean Exploration Institute, Woods Hole Oceanographic Institution
• Glossary of Volcanic Terms from USGS
• How Volcanoes Work by Tom Harris
• How Volcanoes Work - Educational resource on the science and processes behind volcanoes, intended for university students of geology, volcanology and teachers of earth science. The Woods Hole Oceanographic Institution (WHOI is a private nonprofit research and higher education facility dedicated to the study of all aspects of marine science and engineering and
• Volcano Live - John Seach
• Volcanic Materials Identification
• Natural Disasters - Volcano
• Google Video: Erupting Volcano
• Google Maps Plot of World Volcanoes
• University of Washington Libraries: Digital Collections:
  • Mount St. Helens Post-Eruption Chemistry Database This collection contains photographs of Mount St. Helens, post-eruption, taken over the span of three years to provide a look at both the human and the scientific sides of studying the eruption of a volcano.
  • Mount St. Helens Succession Collection This collection consists of 235 photographs in a study of plant habitats following the May 18, 1980 eruption of Mount St. Helens.
• Volcanic Features of Hawaii and Other Worlds
• National Geographic volcano videos