"hydrothermal system. A prominent steam plume marks the site of Big Boiler, the largest fumarole (steam and volcanic-gas vent) in the park. The temperature of the high-velocity steam jetting from it has been measured as high as . A thin crust of material often covers these boiling hot features, making them a serious burn hazard to anyone walking off trail. The steam-heated waters of the features are typically acidic and, even if cool enough, are not safe for bathing. Geology of the Lassen volcanic area The geology of the Lassen volcanic area presents a record of sedimentation and volcanic activity"
"Fumarole A fumarole (or ""fumerole"" – the word ultimately comes from the Latin ""fumus"", ""smoke"") is an opening in a planet's 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 condenses as its pressure drops when it emerges from the ground. The name solfatara, from the Italian ""solfo"", ""sulfur"" (via the Sicilian language – compare to the volcano Solfatara), is given to fumaroles that emit sulfurous gases. Fumaroles may occur along tiny cracks or long fissures, in chaotic clusters or fields,"
"Diatreme A diatreme, sometimes known as a maar-diatreme volcano, is a volcanic pipe formed by a gaseous explosion. When magma rises up through a crack in the Earth's crust and makes contact with a shallow body of ground water, rapid expansion of heated water vapor and volcanic gases can cause a series of explosions. A relatively shallow crater is left (known as a maar) and a rock filled fracture (the actual diatreme) in the Earth's crust. Diatremes breach the Earth's surface and produce a steep inverted cone shape. The term diatreme has been applied more generally to any concave body"
"or without suspended crystals and gas bubbles, is called magma. It rises because it is less dense than the rock from which it was created. When magma reaches the surface from beneath water or air, it is called lava. Eruptions of volcanoes into air are termed ""subaerial"", whereas those occurring underneath the ocean are termed ""submarine"". Black smokers and mid-ocean ridge basalt are examples of submarine volcanic activity. The volume of extrusive rock erupted annually by volcanoes varies with plate tectonic setting. Extrusive rock is produced in the following proportions: Magma that erupts from a volcano behaves according to its"
"Vulcanian eruption The term ""vulcanian"" was first used by Giuseppe Mercalli, witnessing the 1888–1890 eruptions on the island of Vulcano. His description of the eruption style is now used all over the world for eruptions characterised by a dense cloud of ash-laden gas exploding from the crater and rising high above the peak. Mercalli described vulcanian eruptions as ""...Explosions like cannon fire at irregular intervals..."" Their explosive nature is due to increased silica content of the magma. Almost all types of magma can be involved, but magma with about 55% or more silica (e.g. basaltic andesite) is most common. Increasing"
"a type of volcanic eruption, named after the volcano Vulcano. It was named so following Giuseppe Mercalli's observations of its 1888–1890 eruptions. In Vulcanian eruptions, intermediate viscous magma within the volcano make it difficult for vesiculate gases to escape. Similar to Strombolian eruptions, this leads to the buildup of high gas pressure, eventually popping the cap holding the magma down and resulting in an explosive eruption. However, unlike Strombolian eruptions, ejected lava fragments are not aerodynamic; this is due to the higher viscosity of Vulcanian magma and the greater incorporation of crystalline material broken off from the former cap. They"
"Volcanic crater A volcanic crater is a roughly circular depression in the ground caused by volcanic activity. It is typically a bowl-shaped feature within which occurs a vent or vents. During volcanic eruptions, molten magma and volcanic gases rise from an underground magma chamber, through a tube-shaped conduit, until they reach the crater's vent, from where the gases escape into the atmosphere and the magma is erupted as lava. A volcanic crater can be of large dimensions, and sometimes of great depth. During certain types of explosive eruptions, a volcano's magma chamber may empty enough for an area above it"
"Dominica. Fumaroles emitting sulfurous vapors form surface deposits of sulfur-rich minerals; places in which these deposits have been mined include: The formation called Home Plate at Gusev Crater on Mars, which was examined by the Mars Exploration Rover (MER) ""Spirit"", is suspected to be the eroded remains of an ancient and extinct fumarole. Fumarole A fumarole (or ""fumerole"" – the word ultimately comes from the Latin ""fumus"", ""smoke"") is an opening in a planet's 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"
"Volcanic plug 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, and this can sometimes lead to an explosive eruption. 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"
"Vulcan (inactive volcano) Vulcan, named after the Roman god of fire, is an inactive volcano on Albuquerque, New Mexico's West Mesa. It is the largest of the volcanoes in Albuquerque's Volcanic Field . Vulcan is a spatter cone, formed primarily by fire fountains that were active in the central vent and in smaller vents on flanks of the cone. These flank vents formed the arches and caves seen today. From a vantage point on top of the cone 600 feet above valley floor, the alignment of the 5-mile-long chain of vents is particularly noticeable. (Spatter forms when blobs of lava"
"Volcanic gas Volcanic gases are gases given off by active (or, at times, by dormant) volcanoes. These include gases trapped in cavities (vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating directly from lava or indirectly through ground water heated by volcanic action. The sources of volcanic gases on Earth include: Substances that may become gaseous or give off gases when heated are termed volatile substances. The principal components of volcanic gases are water vapor (HO), carbon dioxide (CO), sulfur either as sulfur dioxide (SO) (high-temperature volcanic gases) or hydrogen sulfide (HS) (low-temperature volcanic"
"volcanic gas rises through cracks and fissures in the earth's surface and dissolves partly in the ground water to carbonic acid. The source is a calcium-sodium-bicarbonate-sorrel. The spring water is very cloudy with sediment. Wallender Born The Wallender Born or Wallenborn (popularly known as the Brubbel) is a cold water geyser in the village Wallenborn (Eifel district, Germany). It is adjacent to the reactivated Andernach Geyser (aka ""Namedyer Sprudel"") an active cold water geyser in Germany. Experts disagree on whether the Wallender Born can be described as eruptive course, but periodic gas outbreaks have been witnessed since time immemorial. Until"
"called gas slugs. These grow large enough to rise through the lava column. Upon reaching the surface, the difference in air pressure causes the bubble to burst with a loud pop, throwing magma in the air in a way similar to a soap bubble. Because of the high gas pressures associated with the lavas, continued activity is generally in the form of episodic explosive eruptions accompanied by the distinctive loud blasts. During eruptions, these blasts occur as often as every few minutes. The term ""Strombolian"" has been used indiscriminately to describe a wide variety of volcanic eruptions, varying from small"
"is a flooded fumarole, an opening, crack or hole, in the Earth's crust, generally located within the vicinity of a volcano, which emits steam and gases escaping from molten lava below. Currently, the lake is viewable from a broad, cliff-top ledge about directly above its shore. High rock walls surround and create the basin. The lake's grayish-blue water is easily viewed in its perpetual rolling-boil state which looks like a giant pot of water cooking and steaming on a stove. The basin's water is replenished by rainfall and two small streams which drain into the area. The water then seeps"
"Mamelon (volcanology) A mamelon (from French ""mamelon"", ""nipple"") is a rock formation created by eruption of relatively thick or stiff lava through a narrow vent in the bedrock. Because the lava is not fluid, it does not flow away; instead it congeals around the vent, forming a small hill or mound on the surface. The outflow from successive eruptions forms additional layers on top, and the resulting pile of layers may stand over above the surrounding surface. The term was coined by the French explorer and naturalist Jean Baptiste Bory de Saint-Vincent, to describe the central peak of the Dolomieu"
"volcanic gas (>400 °C). In explosive volcanic eruptions, the sudden release of gases from magma may cause rapid movements of the molten rock. When the magma encounters water, seawater, lake water or groundwater, it can be rapidly fragmented. The rapid expansion of gases is the driving mechanism of most explosive volcanic eruptions. However, a significant portion of volcanic gas release occurs during quasi-continuous quiescent phases of active volcanism. As magmatic gas travelling upward encounters meteoric water in an aquifer, steam is produced. Latent magmatic heat can also cause meteoric waters to ascend as a vapour phase. Extended fluid-rock interaction of"
"Volcanism Volcanism is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics and volcanic gases erupt through a break in the surface called a vent. It includes all phenomena resulting from and causing magma within the crust or mantle of the body, to rise through the crust and form volcanic rocks on the surface. Magma from the mantle or lower crust rises through its crust towards the surface. If magma reaches the surface, its behavior depends on the viscosity of the molten constituent rock. Viscous (thick)"
"domes. They are commonly called ""ticks"" because they appear as domes with numerous ""legs"". They are thought to have undergone mass wasting events such as landslides on their margins. Sometimes deposits of debris can be seen scattered around them. On Earth, volcanoes are mainly of two types: shield volcanoes and composite or stratovolcanoes. The shield volcanoes, for example those in Hawaii, eject magma from the depths of the Earth in zones called ""hot spots"". The lava from these volcanos is relatively fluid and permits the escape of gases. Composite volcanos, such as Mount Saint Helens and Mount Pinatubo, are associated"
"(the extrusive equivalents of gabbro, diorite and granite, respectively). During a volcanic eruption the magma that leaves the underground is called lava. Lava cools and solidifies relatively quickly compared to underground bodies of magma. This fast cooling does not allow crystals to grow large, and a part of the melt does not crystallize at all, becoming glass. Rocks largely composed of volcanic glass include obsidian, scoria and pumice. Before and during volcanic eruptions, volatiles such as CO and HO partially leave the melt through a process known as exsolution. Magma with low water content becomes increasingly viscous. If massive exsolution"
"Phreatic eruption A phreatic eruption, also called a phreatic explosion, ultravulcanian eruption or steam-blast eruption, occurs when magma heats ground or surface water. The extreme temperature of the magma (anywhere from ) causes near-instantaneous evaporation to steam, resulting in an explosion of steam, water, ash, rock, and volcanic bombs. At Mount St. Helens, hundreds of steam explosions preceded a 1980 plinian eruption of the volcano. A less intense geothermal event may result in a mud volcano. Phreatic eruptions typically include steam and rock fragments; the inclusion of liquid lava is unusual. The temperature of the fragments can range from cold"
"(or steam-blast eruptions) are a type of eruption driven by the expansion of steam. When cold ground or surface water come into contact with hot rock or magma it superheats and explodes, fracturing the surrounding rock and thrusting out a mixture of steam, water, ash, volcanic bombs, and volcanic blocks. The distinguishing feature of phreatic explosions is that they only blast out fragments of pre-existing solid rock from the volcanic conduit; no new magma is erupted. Because they are driven by the cracking of rock strata under pressure, phreatic activity does not always result in an eruption; if the rock"
"upper atmosphere (or stratosphere). Historically, 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. Because the crust is very thin at these ridges due to the pull of the tectonic plates, the release of"
"used to reproduce the effects of a natural mofette. Mofetta Mofetta (Italian from Latin ""mephītis"", a pestilential exhalation), is a name applied to a volcanic discharge consisting chiefly of carbon dioxide, often associated with other vapours, representing the final phase of volcanic activity. The Oxford Dictionary of English lists ""mofetta"" as an archaic term for the modern word fumarole. The word is used in the plural as ""mofette"", or, following the French fashion, ""mofettes"". The volcanic vents yielding the emanations are themselves called mofette. They are not uncommon in Auvergne and in the Eifel, notably on the shore of the"
"volcano dating from the Jurassic period. A small hill known as ""Kwun Yum Shan"" near the mountain still vents warm air though cracks in the rocks that lead all the way to the mantle. The holes that exhale warm air are known as ""hot pots"". When the surface temperature is cold, and the warmth of the expelled air is clearly discernible, this phenomenon is referred to by locals as ""dragon's breath"". If the air temperature at the summit is 6 degrees Celsius, then the air emerging from the interior of Kwun Yum Shan is somewhere between 13 and 21 degrees"
"were proposed for volcano behavior before the modern understanding of the Earth's mantle structure as a semisolid material was developed. For decades after awareness that compression and radioactive materials may be heat sources, their contributions were specifically discounted. Volcanic action was often attributed to chemical reactions and a thin layer of molten rock near the surface. Volcano 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. Earth's volcanoes occur because its crust is broken into 17 major,"
"Darvaza gas crater The Darvaza gas crater (, ""Җәхеннем дервезеси""), known locally as the ""Door to Hell"" or <nowiki>""</nowiki>Gates of Hell"", is a natural gas field collapsed into an underground cavern located in Derweze, Turkmenistan. Geologists set it on fire to prevent the spread of methane gas, and it is thought to have been burning continuously since 1971. The diameter of the crater is , and its depth is . The crater is a popular tourist attraction. Since 2009, 50,000 tourists have visited the site. The gas crater has a total area of . The surrounding area is also popular"
"the result of interaction with meteoric water, suggesting that Vulcanian eruptions are partially hydrovolcanic. Volcanoes that have exhibited Vulcanian activity include: Peléan eruptions (or nuée ardente) are a type of volcanic eruption, named after the volcano Mount Pelée in Martinique, the site of a massive Peléan eruption in 1902 that is one of the worst natural disasters in history. In Peléan eruptions, a large amount of gas, dust, ash, and lava fragments are blown out the volcano's central crater, driven by the collapse of rhyolite, dacite, and andesite lava dome collapses that often create large eruptive columns. An early sign"
"mantle wedge formed between the subducting and overriding plates lowers the melting point enough to allow magma to form. The melted material then rises to the surface and forms a volcano—in this case, the Aleutian Arc. The native Aleut name for Mount Cleveland is ""Chuginadak"" (the name currently given to the island as a whole), referring to the Aleut fire goddess, thought to reside in the volcano. The volcano's name is a reference to its constant activity, and shows that it was likely highly active even in the distant past. Aleut oral tradition states that, at one time, the western"
"Firedamp Firedamp is flammable gas found in coal mines. It is the name given to a number of flammable gases, especially methane. It is particularly found in areas where the coal is bituminous. The gas accumulates in pockets in the coal and adjacent strata, and when they are penetrated, the release can trigger explosions. Historically, if such a pocket was highly pressurized, it was termed a ""bag of foulness"". Damps is the collective name given to all gases (other than air) found in coal mines in Great Britain. The word corresponds to German ""Dampf"", the name for ""vapour"". Alongside firedamp,"
"Types of volcanic eruptions Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), 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"
"the chamber is exposed atmospherically to the surface, it is referred to as a ""chimney"". It is at the point that a chimney is formed through which radioactive fallout may reach the surface. At the Nevada Test Site, depths of were used for tests. When the material above the explosion is solid rock, then a mound may be formed by broken rock that has a greater volume. This type of mound has been called ""retarc"", ""crater"" spelled backwards. When a drilling oil well encounters high-pressured gas which cannot be contained either by the weight of the drilling mud or by"
"Volcano 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. Earth's volcanoes occur because its crust is broken into 17 major, rigid tectonic plates that float on a hotter, softer layer in its mantle. Therefore, on Earth, volcanoes are generally found where tectonic plates are diverging or converging, and most are found underwater. For example, a mid-oceanic ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has"
"Hawaiian eruption A Hawaiian eruption is a type of volcanic eruption where lava flows from the vent in a relatively gentle, low level eruption; it is so named because it is characteristic of Hawaiian volcanoes. Typically they are effusive eruptions, with basaltic magmas of low viscosity, low content of gases, and high temperature at the vent. Very small amounts of volcanic ash are produced. This type of eruption occurs most often at hotspot volcanoes such as Kīlauea on Hawaii's big island and in Iceland, though it can occur near subduction zones (e.g. Medicine Lake Volcano in California, United States) and"