What eventually happens to the older volcanoes as they move away from the heat source?

"Volcanic eruption" and "Volcanic eruptions" redirect hither. For the short story, see Volcanic Eruption. For the picture show company, see Volcanic Eruptions.

Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and contrasted gases are expelled from a volcanic vent or cleft—have been distinguished by volcanologists. These are often named afterwards famous volcanoes where that type of behavior has been observed. Some volcanoes may exhibit only one feature type of eruption during a catamenia of activity, while others may brandish an unabridged sequence of types all in one eruptive series.

There are three unlike types of eruptions:

• Magmatic eruptions are the well-nigh well-observed type of eruption. They involve the decompression of gas within magma that propels it forward.
• Phreatic eruptions are driven by the superheating of steam via contact with magma. This type oftentimes exhibits no magmatic release, instead causing the granulation of existing rock.
• Phreatomagmatic eruptions are driven past the pinch of gas inside magma, the direct contrary of the process powering magmatic action.

Within these wide-defining eruptive types are several subtypes. The weakest are Hawaiian and submarine, and so Strombolian, followed by Vulcanian and Surtseyan. The stronger eruptive types are Pelean eruptions, followed by Plinian eruptions; the strongest eruptions are called Ultra-Plinian. Subglacial and phreatic eruptions are defined past their eruptive mechanism, and vary in forcefulness. An of import measure of eruptive strength is the Volcanic Explosivity Index (VEI), an lodge-of-magnitude scale, ranging from 0 to 8, that often correlates to eruptive types.

Eruption mechanisms [edit]

Diagram showing the calibration of VEI correlation with total ejecta book

Volcanic eruptions arise through three principal mechanisms:^[1]

• Gas release nether decompression, causing magmatic eruptions
• Ejection of entrained particles during steam eruptions, causing phreatic eruptions
• Thermal contraction from chilling on contact with water, causing phreatomagmatic eruptions

In that location are 2 types of eruptions in terms of activity, explosive eruptions and effusive eruptions. Explosive eruptions are characterized by gas-driven explosions that propels magma and tephra.^[1] Effusive eruptions, meanwhile, are characterized past the outpouring of lava without significant explosive eruption.^[2]

Volcanic eruptions vary widely in strength. On the one farthermost there are effusive Hawaiian eruptions, which are characterized by lava fountains and fluid lava flows, which are typically not very dangerous. On the other extreme, Plinian eruptions are large, violent, and highly dangerous explosive events. Volcanoes are not bound to one eruptive way, and ofttimes display many different types, both passive and explosive, even in the bridge of a single eruptive cycle.^[3] Volcanoes do non always erupt vertically from a single crater about their superlative, either. Some volcanoes exhibit lateral and Fissure eruptions. Notably, many Hawaiian eruptions start from rift zones,^[iv] and some of the strongest Surtseyan eruptions develop forth fracture zones.^[v] Scientists believed that pulses of magma mixed together in the magma bedroom before climbing upwardly—a procedure estimated to accept several thousands of years. Notwithstanding, Columbia University volcanologists found that the eruption of Republic of costa rica'southward Irazú Volcano in 1963 was probable triggered past magma that took a nonstop road from the drape over just a few months.^[6]

Volcanic Explosivity Alphabetize [edit]

The Volcanic Explosivity Index (normally shortened to VEI) is a scale, from 0 to 8, for measuring the strength of eruptions. Information technology is used past the Smithsonian Institution's Global Volcanism Program in assessing the touch on of historic and prehistoric lava flows. It operates in a way similar to the Richter calibration for earthquakes, in that each interval in value represents a tenfold increasing in magnitude (it is logarithmic).^[7] The vast majority of volcanic eruptions are of VEIs between 0 and 2.^[3]

Volcanic eruptions by VEI alphabetize ^[vii]

VEI	Feather meridian	Eruptive volume *	Eruption type	Frequency **	Example
0	<100 1000 (330 ft)	1,000 thou3 (35,300 cu ft)	Hawaiian	Continuous	Kilauea
1	100–ane,000 m (300–three,300 ft)	10,000 thousandthree (353,000 cu ft)	Hawaiian/Strombolian	Daily	Stromboli
2	one–5 km (1–3 mi)	1,000,000 chiliad3 (35,300,000 cu ft) †	Strombolian/Vulcanian	Fortnightly	Galeras (1992)
3	3–15 km (ii–9 mi)	10,000,000 mthree (353,000,000 cu ft)	Vulcanian	3 months	Nevado del Ruiz (1985)
iv	10–25 km (6–xvi mi)	100,000,000 grand3 (0.024 cu mi)	Vulcanian/Peléan	eighteen months	Eyjafjallajökull (2010)
5	>25 km (16 mi)	one km3 (0.24 cu mi)	Plinian	ten–15 years	Mount St. Helens (1980)
6	>25 km (xvi mi)	10 km3 (2 cu mi)	Plinian/Ultra-Plinian	50–100 years	Mountain Pinatubo (1991)
7	>25 km (16 mi)	100 km3 (twenty cu mi)	Ultra-Plinian	500–1000 years	Tambora (1815)
8	>25 km (16 mi)	i,000 km3 (200 cu mi)	Supervolcanic	l,000+ years[8] [nine]	Lake Toba (74 k.y.a.)
* This is the minimum eruptive volume necessary for the eruption to be considered within the category. ** Values are a rough estimate. They signal the frequencies for volcanoes of that magnitude OR College † There is a aperture between the 1st and 2nd VEI level; instead of increasing by a magnitude of x, the value increases by a magnitude of 100 (from 10,000 to 1,000,000).

Magmatic eruptions [edit]

Magmatic eruptions produce juvenile clasts during explosive decompression from gas release. They range in intensity from the relatively small lava fountains on Hawaii to catastrophic Ultra-Plinian eruption columns more than 30 km (xix mi) loftier, bigger than the eruption of Mount Vesuvius in 79 that buried Pompeii.^[1]

Hawaiian [edit]

Hawaiian eruptions are a type of volcanic eruption named later the Hawaiian volcanoes with which this eruptive blazon is hallmark. Hawaiian eruptions are the calmest types of volcanic events, characterized by the effusive eruption of very fluid basalt-type lavas with low gaseous content. The book of ejected cloth from Hawaiian eruptions is less than one-half of that found in other eruptive types. Steady production of minor amounts of lava builds upwards the large, broad form of a shield volcano. Eruptions are not centralized at the main top every bit with other volcanic types, and often occur at vents around the acme and from fissure vents radiating out of the centre.^[iv]

Hawaiian eruptions oftentimes begin every bit a line of vent eruptions forth a fissure vent, a so-called "curtain of fire." These die down as the lava begins to concentrate at a few of the vents. Central-vent eruptions, meanwhile, oft take the form of big lava fountains (both continuous and sporadic), which can reach heights of hundreds of meters or more than. The particles from lava fountains usually cool in the air before hitting the ground, resulting in the accumulation of cindery scoria fragments; nonetheless, when the air is especially thick with clasts, they cannot cool off fast plenty due to the surrounding heat, and hitting the footing still hot, the accumulation of which forms spatter cones. If eruptive rates are high enough, they may fifty-fifty form splatter-fed lava flows. Hawaiian eruptions are often extremely long lived; Puʻu ʻŌʻō, a volcanic cone on Kilauea, erupted continuously for over 35 years. Another Hawaiian volcanic feature is the formation of active lava lakes, self-maintaining pools of raw lava with a thin crust of semi-cooled rock.^[4]

Flows from Hawaiian eruptions are basaltic, and can be divided into 2 types by their structural characteristics. Pahoehoe lava is a relatively smooth lava flow that can be billowy or ropey. They can move as one sheet, by the advancement of "toes," or as a snaking lava column.^[x] A'a lava flows are denser and more viscous than pahoehoe, and tend to move slower. Flows can measure 2 to 20 m (7 to 66 ft) thick. A'a flows are so thick that the outside layers cools into a rubble-similar mass, insulating the still-hot interior and preventing it from cooling. A'a lava moves in a peculiar mode—the forepart of the flow steepens due to pressure from behind until it breaks off, after which the general mass behind it moves forrard. Pahoehoe lava tin can sometimes become A'a lava due to increasing viscosity or increasing rate of shear, merely A'a lava never turns into pahoehoe menstruum.^[11]

Hawaiian eruptions are responsible for several unique volcanological objects. Pocket-sized volcanic particles are carried and formed by the wind, chilling quickly into teardrop-shaped glassy fragments known as Pele'due south tears (afterward Pele, the Hawaiian volcano deity). During especially high winds these chunks may even take the class of long drawn-out strands, known as Pele's pilus. Sometimes basalt aerates into reticulite, the lowest density stone type on globe.^[4]

Although Hawaiian eruptions are named after the volcanoes of Hawaii, they are not necessarily restricted to them; the largest lava fountain always recorded formed on the island of Izu Ōshima (on Mount Mihara) in 1986, a 1,600 m (five,249 ft) gusher that was more than twice as high every bit the mountain itself (which stands at 764 m (2,507 ft)).^{[4] [12]}

Volcanoes known to have Hawaiian activity include:

• Puʻu ʻŌʻō, a parasitic cinder cone located on Kilauea on the island of Hawaiʻi which erupted continuously from 1983 to 2018. The eruptions began with a half-dozen km (four mi)-long cleft-based "mantle of fire" on three January 1983. These gave mode to centralized eruptions on the site of Kilauea'due south east rift, somewhen building upwards the cone.^[four]
• For a list of all of the volcanoes of Hawaii, meet List of volcanoes in the Hawaiian – Emperor seamount chain.
• Mountain Etna, Italy.^[4]
• Mount Mihara in 1986 (see above paragraph)^[iv]

Strombolian [edit]

Strombolian eruptions are a type of volcanic eruption named later the volcano Stromboli, which has been erupting nearly continuously for centuries.^[13] Strombolian eruptions are driven by the bursting of gas bubbles within the magma. These gas bubbles within the magma accrue and coalesce into big bubbling, chosen gas slugs. These grow big enough to ascension through the lava column.^[xiv] Upon reaching the surface, the difference in air pressure causes the chimera to burst with a loud pop,^[13] throwing magma in the air in a mode similar to a lather bubble. Because of the loftier gas pressures associated with the lavas, continued action is generally in the form of episodic explosive eruptions accompanied by the distinctive loud blasts.^[xiii] During eruptions, these blasts occur as often every bit every few minutes.^[fifteen]

The term "Strombolian" has been used indiscriminately to depict a wide diversity of volcanic eruptions, varying from small-scale volcanic blasts to large eruptive columns. In reality, true Strombolian eruptions are characterized by short-lived and explosive eruptions of lavas with intermediate viscosity, oft ejected high into the air. Columns can measure hundreds of meters in pinnacle. The lavas formed by Strombolian eruptions are a class of relatively pasty basaltic lava, and its end product is generally scoria.^[13] The relative passivity of Strombolian eruptions, and its non-damaging nature to its source vent allow Strombolian eruptions to proceed unabated for thousands of years, and likewise makes information technology one of the least dangerous eruptive types.^[15]

An example of the lava arcs formed during Strombolian action. This image is of Stromboli itself.

Strombolian eruptions squirt volcanic bombs and lapilli fragments that travel in parabolic paths before landing around their source vent.^[16] The steady accumulation of modest fragments builds cinder cones composed completely of basaltic pyroclasts. This form of accumulation tends to result in well-ordered rings of tephra.^[xiii]

Strombolian eruptions are similar to Hawaiian eruptions, simply there are differences. Strombolian eruptions are noisier, produce no sustained eruptive columns, practise not produce some volcanic products associated with Hawaiian volcanism (specifically Pele's tears and Pele'southward pilus), and produce fewer molten lava flows (although the eruptive material does tend to course small rivulets).^{[13] [15]}

Volcanoes known to accept Strombolian activity include:

• Parícutin, Mexico, which erupted from a fissure in a cornfield in 1943. Ii years into its life, pyroclastic action began to wane, and the outpouring of lava from its base became its chief way of activeness. Eruptions ceased in 1952, and the final height was 424 m (1,391 ft). This was the first time that scientists are able to observe the complete life cycle of a volcano.^[13]
• Mountain Etna, Italy, which has displayed Strombolian activity in recent eruptions, for example in 1981, 1999,^[17] 2002–2003, and 2009.^[18]
• Mount Erebus in Antarctica, the southernmost agile volcano in the world, having been observed erupting since 1972.^[19] Eruptive action at Erebus consists of frequent Strombolian activeness.^[twenty]
• Stromboli itself. The namesake of the mild explosive activity that it possesses has been active throughout historical fourth dimension; essentially continuous Strombolian eruptions, occasionally accompanied by lava flows, have been recorded at Stromboli for more than a millennium.^[21]

Vulcanian [edit]

Vulcanian eruptions are a type of volcanic eruption named after the volcano Vulcano.^[22] Information technology was named and so following Giuseppe Mercalli's observations of its 1888–1890 eruptions.^[23] 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 downward and resulting in an explosive eruption. However, dissimilar 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 are also more than explosive than their Strombolian counterparts, with eruptive columns often reaching betwixt 5 and x km (3 and 6 mi) high. Lastly, Vulcanian deposits are andesitic to dacitic rather than basaltic.^[22]

Initial Vulcanian activity is characterized by a series of brusque-lived explosions, lasting a few minutes to a few hours and typified by the ejection of volcanic bombs and blocks. These eruptions wearable downward the lava dome holding the magma downward, and it disintegrates, leading to much more than quiet and continuous eruptions. Thus an early sign of future Vulcanian activity is lava dome growth, and its collapse generates an outpouring of pyroclastic material down the volcano's gradient.^[22]

Deposits most the source vent consist of large volcanic blocks and bombs, with then-called "bread-crust bombs" being especially common. These deeply cracked volcanic chunks form when the exterior of ejected lava cools quickly into a glassy or fine-grained crush, but the inside continues to cool and vesiculate. The center of the fragment expands, cracking the exterior. Withal the bulk of Vulcanian deposits are fine grained ash. The ash is only moderately dispersed, and its abundance indicates a high caste of fragmentation, the effect of high gas contents within the magma. In some cases these take been plant to be the issue of interaction with meteoric water, suggesting that Vulcanian eruptions are partially hydrovolcanic.^[22]

Volcanoes that have exhibited Vulcanian action include:

• Sakurajima, Japan has been the site of Vulcanian activeness near-continuously since 1955.^[24]
• Tavurvur, Papua New Guinea, one of several volcanoes in the Rabaul Caldera.^[22]
• Irazú Volcano in Costa Rica exhibited Vulcanian activity in its 1965 eruption.^[25]

Vulcanian eruptions are estimated to make upwards at least half of all known Holocene eruptions.^[26]

Peléan [edit]

Peléan eruptions (or nuée ardente) are a type of volcanic eruption named afterwards the volcano Mountain Pelée in Martinique, the site of a 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'due south cardinal crater,^[27] driven by the collapse of rhyolite, dacite, and andesite lava dome collapses that often create large eruptive columns. An early sign of a coming eruption is the growth of a so-called Peléan or lava spine, a bulge in the volcano's summit preempting its total collapse.^[28] The material collapses upon itself, forming a fast-moving pyroclastic menstruation^[27] (known as a block-and-ash flow)^[29] that moves downwards the side of the mount at tremendous speeds, often over 150 km (93 mi) per hr. These landslides make Peléan eruptions one of the most dangerous in the world, capable of tearing through populated areas and causing serious loss of life. The 1902 eruption of Mount Pelée acquired tremendous destruction, killing more than xxx,000 people and completely destroying St. Pierre, the worst volcanic event in the 20th century.^[27]

Peléan eruptions are characterized most prominently past the incandescent pyroclastic flows that they bulldoze. The mechanics of a Peléan eruption are very similar to that of a Vulcanian eruption, except that in Peléan eruptions the volcano's structure is able to withstand more pressure level, hence the eruption occurs as one large explosion rather than several smaller ones.^[thirty]

Volcanoes known to accept Peléan activeness include:

• Mount Pelée, Martinique. The 1902 eruption of Mountain Pelée completely devastated the isle, destroying St. Pierre and leaving only iii survivors.^[31] The eruption was straight preceded by lava dome growth.^[22]
• Mayon Volcano, the Philippines most active volcano. It has been the site of many unlike types of eruptions, Peléan included. Approximately 40 ravines radiate from the pinnacle and provide pathways for frequent pyroclastic flows and mudflows to the lowlands below. Mayon's nearly tearing eruption occurred in 1814 and was responsible for over 1200 deaths.^[32]
• The 1951 eruption of Mountain Lamington. Prior to this eruption the elevation had non fifty-fifty been recognized as a volcano. Over 3,000 people were killed, and it has get a benchmark for studying large Peléan eruptions.^[33]

Plinian [edit]

Plinian eruptions (or Vesuvian eruptions) are a type of volcanic eruption named for the historical eruption of Mount Vesuvius in 79 Advertizing that buried the Roman towns of Pompeii and Herculaneum and, specifically, for its chronicler Pliny the Younger.^[34] The process powering Plinian eruptions starts in the magma chamber, where dissolved volatile gases are stored in the magma. The gases vesiculate and accumulate as they ascension through the magma conduit. These bubbles agglutinate and once they reach a certain size (well-nigh 75% of the full book of the magma conduit) they explode. The narrow confines of the conduit force the gases and associated magma up, forming an eruptive cavalcade. Eruption velocity is controlled by the gas contents of the column, and low-strength surface rocks commonly crack nether the pressure level of the eruption, forming a flared approachable structure that pushes the gases even faster.^[35]

These massive eruptive columns are the distinctive feature of a Plinian eruption, and accomplish up two to 45 km (1 to 28 mi) into the temper. The densest part of the plume, straight to a higher place the volcano, is driven internally by gas expansion. As it reaches college into the air the plume expands and becomes less dense, convection and thermal expansion of volcanic ash drive it even further upwards into the stratosphere. At the top of the plumage, powerful prevailing winds drive the plume in a management abroad from the volcano.^[35]

These highly explosive eruptions are usually associated with volatile-rich dacitic to rhyolitic lavas, and occur about typically at stratovolcanoes. Eruptions can final anywhere from hours to days, with longer eruptions being associated with more felsic volcanoes. Although they are unremarkably associated with felsic magma, Plinian eruptions can occur at basaltic volcanoes, if the magma sleeping room differentiates with upper portions rich in silicon dioxide,^[34] or if magma ascends chop-chop.^[36]

Plinian eruptions are similar to both Vulcanian and Strombolian eruptions, except that rather than creating discrete explosive events, Plinian eruptions form sustained eruptive columns. They are too like to Hawaiian lava fountains in that both eruptive types produce sustained eruption columns maintained by the growth of bubbles that move up at about the same speed as the magma surrounding them.^[34]

Regions affected by Plinian eruptions are subjected to heavy pumice airfall affecting an expanse 0.five to 50 km³ (0 to 12 cu mi) in size.^[34] The fabric in the ash plume eventually finds its way back to the basis, roofing the landscape in a thick layer of many cubic kilometers of ash.^[37]

However the almost dangerous eruptive feature are the pyroclastic flows generated by textile collapse, which move down the side of the mountain at extreme speeds^[34] of up to 700 km (435 mi) per 60 minutes and with the ability to extend the reach of the eruption hundreds of kilometers.^[37] The ejection of hot material from the volcano's summit melts snowbanks and water ice deposits on the volcano, which mixes with tephra to course lahars, fast moving mudflows with the consistency of moisture concrete that move at the speed of a river rapid.^[34]

Major Plinian eruptive events include:

• The Advertizing 79 eruption of Mount Vesuvius buried the Roman towns of Pompeii and Herculaneum under a layer of ash and tephra.^[38] Information technology is the model Plinian eruption. Mount Vesuvius has erupted several times since then. Its last eruption was in 1944 and caused problems for the allied armies every bit they advanced through Italian republic.^[34] Information technology was the contemporary report by Pliny the Younger that led scientists to refer to Vesuvian eruptions as "Plinian".
• The 1980 eruption of Mount St. Helens in Washington, which ripped apart the volcano'southward top, was a Plinian eruption of Volcanic Explosivity Index (VEI) 5.^[3]
• The strongest types of eruptions, with a VEI of 8, are so-called "Ultra-Plinian" eruptions, such as the 1 at Lake Toba 74 yard years ago, which put out 2800 times the material erupted by Mountain St. Helens in 1980.^{[7] [39]}
• Hekla in Iceland, an example of basaltic Plinian volcanism being its 1947–48 eruption. The past 800 years have been a pattern of violent initial eruptions of pumice followed by prolonged extrusion of basaltic lava from the lower role of the volcano.^[34]
• Pinatubo in the Philippines on 15 June 1991, which produced 5 km³ (1 cu mi) of dacitic magma, a xl km (25 mi) high eruption column, and released 17 megatons of sulfur dioxide.^[twoscore]

Phreatomagmatic eruptions [edit]

Phreatomagmatic eruptions are eruptions that arise from interactions between water and magma. They are driven by thermal contraction of magma when it comes in contact with water (equally distinguished from magmatic eruptions, which are driven by thermal expansion).^{[ clarification needed ]} This temperature divergence between the two causes violent water-lava interactions that make up the eruption. The products of phreatomagmatic eruptions are believed to be more regular in shape and finer grained than the products of magmatic eruptions because of the differences in eruptive mechanisms.^{[1] [41]}

There is contend about the verbal nature of phreatomagmatic eruptions, and some scientists believe that fuel-coolant reactions may be more critical to the explosive nature than thermal contraction.^[41] Fuel coolant reactions may fragment the volcanic cloth by propagating stress waves, widening cracks and increasing surface area that ultimately leads to rapid cooling and explosive contraction-driven eruptions.^[one]

Surtseyan [edit]

A Surtseyan (or hydrovolcanic) eruption is a blazon of volcanic eruption characterized by shallow-water interactions between water and lava, named afterward its nearly famous example, the eruption and formation of the island of Surtsey off the coast of Iceland in 1963. Surtseyan eruptions are the "wet" equivalent of ground-based Strombolian eruptions, but considering they have place in water they are much more explosive. Equally water is heated by lava, it flashes into steam and expands violently, fragmenting the magma information technology contacts into fine-grained ash. Surtseyan eruptions are typical of shallow-water volcanic oceanic islands, but they are not confined to seamounts. They can happen on country as well, where rising magma that comes into contact with an aquifer (water-bearing rock formation) at shallow levels under the volcano can cause them.^[5] The products of Surtseyan eruptions are more often than not oxidized palagonite basalts (though andesitic eruptions do occur, albeit rarely), and like Strombolian eruptions Surtseyan eruptions are generally continuous or otherwise rhythmic.^[42]

A defining feature of a Surtseyan eruption is the formation of a pyroclastic surge (or base surge), a ground hugging radial deject that develops along with the eruption column. Base of operations surges are caused past the gravitational collapse of a vaporous eruptive column, one that is denser overall than a regular volcanic column. The densest part of the cloud is nearest to the vent, resulting in a wedge shape. Associated with these laterally moving rings are dune-shaped depositions of rock left backside by the lateral motility. These are occasionally disrupted by bomb sags, rock that was flung out by the explosive eruption and followed a ballistic path to the ground. Accumulations of moisture, spherical ash known as accretionary lapilli are some other common surge indicator.^[5]

Over time Surtseyan eruptions tend to form maars, broad low-relief volcanic craters dug into the ground, and tuff rings, round structures built of quickly quenched lava. These structures are associated with single vent eruptions. However, if eruptions arise forth fracture zones, rift zones may exist dug out. Such eruptions tend to exist more violent than those which form tuff rings or maars, an example being the 1886 eruption of Mount Tarawera.^{[v] [42]} Coastal cones are another hydrovolcanic feature, generated by the explosive deposition of basaltic tephra (although they are non truly volcanic vents). They class when lava accumulates within cracks in lava, superheats and explodes in a steam explosion, breaking the rock autonomously and depositing it on the volcano's flank. Sequent explosions of this blazon eventually generate the cone.^[5]

Volcanoes known to have Surtseyan activity include:

• Surtsey, Iceland. The volcano built itself upwardly from depth and emerged above the Atlantic Ocean off the coast of Iceland in 1963. Initial hydrovolcanics were highly explosive, but as the volcano grew, rise lava interacted less with water and more with air, until finally Surtseyan activity waned and became more Strombolian.^[v]
• Ukinrek Maars in Alaska, 1977, and Capelinhos in the Azores, 1957, both examples of above-h2o Surtseyan activity.^[5]
• Mount Tarawera in New Zealand erupted along a rift zone in 1886, killing 150 people.^[five]
• Ferdinandea, a seamount in the Mediterranean Body of water, breached sea level in July 1831 and caused a sovereignty dispute between Italia, France, and Great britain. The volcano did not build tuff cones strong enough to withstand erosion and soon disappeared dorsum below the waves.^[43]
• The underwater volcano Hunga Tonga in Tonga breached bounding main level in 2009. Both of its vents exhibited Surtseyan activity for much of the time. Information technology was too the site of an before eruption in May 1988.^[44]

• 

  Surtsey, erupting 13 days later breaching the water. A tuff ring surrounds the vent.

Submarine [edit]

Submarine eruptions are a type of volcanic eruption that occurs underwater. An estimated 75% of the total volcanic eruptive book is generated past submarine eruptions near mid ocean ridges alone, withal because of the problems associated with detecting deep bounding main volcanics, they remained nearly unknown until advances in the 1990s made information technology possible to observe them.^[45]

Submarine eruptions may produce seamounts which may suspension the surface to form volcanic islands and island chains.

Submarine volcanism is driven by diverse processes. Volcanoes nearly plate boundaries and mid-ocean ridges are congenital past the decompression melting of mantle stone that rises on an upwelling portion of a convection jail cell to the crustal surface. Eruptions associated with subducting zones, meanwhile, are driven past subducting plates that add together volatiles to the ascent plate, lowering its melting point. Each procedure generates different rock; mid-sea ridge volcanics are primarily basaltic, whereas subduction flows are mostly calc-alkaline, and more explosive and viscid.^[46]

Spreading rates along mid-ocean ridges vary widely, from 2 cm (0.8 in) per year at the Mid-Atlantic Ridge, to up to 16 cm (6 in) along the East Pacific Rise. Higher spreading rates are a probable crusade for higher levels of volcanism. The engineering for studying seamount eruptions did non be until advancements in hydrophone technology made it possible to "listen" to audio-visual waves, known as T-waves, released past submarine earthquakes associated with submarine volcanic eruptions. The reason for this is that state-based seismometers cannot detect body of water-based earthquakes below a magnitude of iv, but acoustic waves travel well in water and over long periods of time. A system in the North Pacific, maintained by the United States Navy and originally intended for the detection of submarines, has detected an event on boilerplate every 2 to 3 years.^[45]

The most common underwater flow is pillow lava, a round lava flow named afterward its unusual shape. Less common are glassy, marginal canvass flows, indicative of larger-scale flows. Volcaniclastic sedimentary rocks are common in shallow-water environments. As plate movement starts to carry the volcanoes away from their eruptive source, eruption rates start to die down, and water erosion grinds the volcano down. The last stages of eruption cap the seamount in alkalic flows.^[46] At that place are about 100,000 deepwater volcanoes in the earth,^[47] although most are beyond the active phase of their life.^[46] Some exemplary seamounts are Loihi Seamount, Bowie Seamount, Davidson Seamount, and Axial Seamount.

Subglacial [edit]

Subglacial eruptions are a type of volcanic eruption characterized past interactions betwixt lava and ice, often under a glacier. The nature of glaciovolcanism dictates that it occurs at areas of high latitude and high altitude.^[48] It has been suggested that subglacial volcanoes that are not actively erupting often dump estrus into the ice covering them, producing meltwater.^[49] This meltwater mix means that subglacial eruptions oftentimes generate dangerous jökulhlaups (floods) and lahars.^[48]

The written report of glaciovolcanism is yet a relatively new field. Early accounts described the unusual apartment-topped steep-sided volcanoes (called tuyas) in Iceland that were suggested to have formed from eruptions below ice. The first English language-language newspaper on the subject was published in 1947 by William Henry Mathews, describing the Tuya Butte field in northwest British Columbia, Canada. The eruptive procedure that builds these structures, originally inferred in the paper,^[48] begins with volcanic growth below the glacier. At outset the eruptions resemble those that occur in the deep body of water, forming piles of pillow lava at the base of the volcanic structure. Some of the lava shatters when it comes in contact with the cold water ice, forming a burnished breccia called hyaloclastite. After a while the ice finally melts into a lake, and the more than explosive eruptions of Surtseyan activity begins, building up flanks fabricated upwardly of more often than not hyaloclastite. Eventually the lake boils off from continued volcanism, and the lava flows become more effusive and thicken as the lava cools much more slowly, ofttimes forming columnar jointing. Well-preserved tuyas bear witness all of these stages, for example Hjorleifshofdi in Iceland.^[50]

Products of volcano-ice interactions stand as various structures, whose shape is dependent on complex eruptive and ecology interactions. Glacial volcanism is a good indicator of past ice distribution, making it an important climatic marker. Since they are embedded in ice, as glacial water ice retreats worldwide there are concerns that tuyas and other structures may destabilize, resulting in mass landslides. Prove of volcanic-glacial interactions are axiomatic in Republic of iceland and parts of British Columbia, and information technology is even possible that they play a role in deglaciation.^[48]

Glaciovolcanic products accept been identified in Republic of iceland, the Canadian province of British Columbia, the U.Southward. states of Hawaii and Alaska, the Pour Range of western N America, South America and fifty-fifty on the planet Mars.^[48] Volcanoes known to have subglacial activity include:

• Mauna Kea in tropical Hawaii. In that location is evidence of by subglacial eruptive activity on the volcano in the form of a subglacial deposit on its tiptop. The eruptions originated about ten,000 years agone, during the terminal ice historic period, when the summit of Mauna Kea was covered in ice.^[51]
• In 2008, the British Antarctic Survey reported a volcanic eruption nether the Antarctica water ice sheet two,200 years ago. It is believed to be that this was the biggest eruption in Antarctica in the final 10,000 years. Volcanic ash deposits from the volcano were identified through an airborne radar survey, cached under after snowfalls in the Hudson Mountains, close to Pine Isle Glacier.^[49]
• Iceland, well known for both glaciers and volcanoes, is often a site of subglacial eruptions. An case an eruption under the Vatnajökull ice cap in 1996, which occurred under an estimated 2,500 ft (762 m) of water ice.^[52]
• As part of the search for life on Mars, scientists take suggested that there may be subglacial volcanoes on the red planet. Several potential sites of such volcanism have been reviewed, and compared extensively with similar features in Iceland:^[53]

Viable microbial communities take been found living in deep (−2800 k) geothermal groundwater at 349 K and pressures >300 bar. Furthermore, microbes have been postulated to exist in basaltic rocks in rinds of altered volcanic drinking glass. All of these conditions could exist in polar regions of Mars today where subglacial volcanism has occurred.

Phreatic eruptions [edit]

Phreatic eruptions (or steam-blast eruptions) are a type of eruption driven by the expansion of steam. When common cold ground or surface h2o come into contact with hot rock or magma it superheats and explodes, fracturing the surrounding rock^[54] and thrusting out a mixture of steam, water, ash, volcanic bombs, and volcanic blocks.^[55] The distinguishing feature of phreatic explosions is that they but blast out fragments of pre-existing solid stone from the volcanic conduit; no new magma is erupted.^[56] Because they are driven by the bang-up of stone strata under pressure level, phreatic activeness does non always result in an eruption; if the rock confront is strong enough to withstand the explosive forcefulness, outright eruptions may not occur, although cracks in the stone volition probably develop and weaken it, furthering futurity eruptions.^[54]

Often a precursor of futurity volcanic activeness,^[57] phreatic eruptions are mostly weak, although there have been exceptions.^[56] Some phreatic events may exist triggered by earthquake activity, another volcanic forerunner, and they may too travel forth dike lines.^[54] Phreatic eruptions class base surges, lahars, avalanches, and volcanic block "rain." They may besides release mortiferous toxic gas able to suffocate anyone in range of the eruption.^[57]

Volcanoes known to exhibit phreatic activeness include:

• Mount St. Helens, which exhibited phreatic action simply prior to its catastrophic 1980 eruption (which was itself Plinian).^[55]
• Taal Volcano, Philippines, 1965^[56] 2020^[58]
• La Soufrière of Guadeloupe (Lesser Antilles), 1975–1976 activity.^[56]
• Soufrière Hills volcano on Montserrat, West Indies, 1995–2012.
• Poás Volcano, has frequent geyser like phreatic eruptions from its crater lake.
• Mountain Bulusan, well known for its sudden phreatic eruptions.
• Mount Ontake, all historical eruptions of this volcano accept been phreatic including the mortiferous 2014 eruption.
• Mount Sinabung, Indonesia, 2020

See likewise [edit]

• List of large volcanic eruptions in the 21st century
• Listing of Fourth volcanic eruptions
• Prediction of volcanic activity
• Timeline of volcanism on Earth – Wikipedia list commodity

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Further reading [edit]

cotemageting.blogspot.com

Source: https://en.wikipedia.org/wiki/Types_of_volcanic_eruptions

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