King Volcano Rise for You Again and Again

"Volcanic eruption" and "Volcanic eruptions" redirect here. For the short story, see Volcanic Eruption. For the film company, see 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 beliefs has been observed. Some volcanoes may exhibit but one characteristic type of eruption during a period of activeness, while others may display an entire sequence of types all in one eruptive series.

There are three different types of eruptions:

• Magmatic eruptions are the most well-observed type of eruption. They involve the decompression of gas within magma that propels information technology forward.
• Phreatic eruptions are driven by the superheating of steam via contact with magma. This type often exhibits no magmatic release, instead causing the granulation of existing rock.
• Phreatomagmatic eruptions are driven by the compression of gas inside magma, the direct contrary of the procedure powering magmatic activeness.

Within these broad-defining eruptive types are several subtypes. The weakest are Hawaiian and submarine, then Strombolian, followed by Vulcanian and Surtseyan. The stronger eruptive types are Pelean eruptions, followed by Plinian eruptions; the strongest eruptions are called Ultra-Plinian. Subglacial and phreatic eruptions are divers by their eruptive mechanism, and vary in force. An of import measure out of eruptive force is the Volcanic Explosivity Index (VEI), an order-of-magnitude scale, ranging from 0 to 8, that oftentimes correlates to eruptive types.

Eruption mechanisms [edit]

Diagram showing the calibration of VEI correlation with total ejecta volume

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

• Gas release under 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

There are ii types of eruptions in terms of activeness, explosive eruptions and effusive eruptions. Explosive eruptions are characterized by gas-driven explosions that propels magma and tephra.^[i] Effusive eruptions, meanwhile, are characterized by the outpouring of lava without pregnant explosive eruption.^[2]

Volcanic eruptions vary widely in strength. On the one extreme there are effusive Hawaiian eruptions, which are characterized by lava fountains and fluid lava flows, which are typically non very dangerous. On the other extreme, Plinian eruptions are large, trigger-happy, and highly dangerous explosive events. Volcanoes are not bound to i eruptive style, and frequently display many dissimilar types, both passive and explosive, even in the span of a single eruptive cycle.^[3] Volcanoes do not ever erupt vertically from a single crater near their peak, either. Some volcanoes exhibit lateral and Cleft eruptions. Notably, many Hawaiian eruptions starting time from rift zones,^[iv] and some of the strongest Surtseyan eruptions develop along fracture zones.^[5] Scientists believed that pulses of magma mixed together in the magma bedroom before climbing upward—a procedure estimated to take several thousands of years. Nevertheless, Columbia Academy volcanologists establish that the eruption of Costa Rica's Irazú Volcano in 1963 was likely triggered by magma that took a nonstop road from the mantle over merely a few months.^[6]

Volcanic Explosivity Index [edit]

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

Volcanic eruptions by VEI index ^[vii]

VEI	Plume superlative	Eruptive book *	Eruption type	Frequency **	Case
0	<100 m (330 ft)	1,000 k3 (35,300 cu ft)	Hawaiian	Continuous	Kilauea
one	100–one,000 k (300–three,300 ft)	10,000 miii (353,000 cu ft)	Hawaiian/Strombolian	Daily	Stromboli
two	1–five km (1–three mi)	1,000,000 m3 (35,300,000 cu ft) †	Strombolian/Vulcanian	Fortnightly	Galeras (1992)
3	3–fifteen km (two–nine mi)	10,000,000 m3 (353,000,000 cu ft)	Vulcanian	three months	Nevado del Ruiz (1985)
iv	10–25 km (6–16 mi)	100,000,000 g3 (0.024 cu mi)	Vulcanian/Peléan	18 months	Eyjafjallajökull (2010)
5	>25 km (xvi mi)	ane km3 (0.24 cu mi)	Plinian	ten–xv years	Mount St. Helens (1980)
half dozen	>25 km (16 mi)	10 km3 (2 cu mi)	Plinian/Ultra-Plinian	50–100 years	Mountain Pinatubo (1991)
7	>25 km (16 mi)	100 km3 (xx cu mi)	Ultra-Plinian	500–thousand years	Tambora (1815)
8	>25 km (16 mi)	1,000 km3 (200 cu mi)	Supervolcanic	50,000+ 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 guess. They indicate the frequencies for volcanoes of that magnitude OR HIGHER † There is a discontinuity between the 1st and 2nd VEI level; instead of increasing by a magnitude of 10, the value increases by a magnitude of 100 (from 10,000 to ane,000,000).

Magmatic eruptions [edit]

Magmatic eruptions produce juvenile clasts during explosive decompression from gas release. They range in intensity from the relatively pocket-size lava fountains on Hawaii to catastrophic Ultra-Plinian eruption columns more 30 km (19 mi) high, bigger than the eruption of Mount Vesuvius in 79 that buried Pompeii.^[1]

Hawaiian [edit]

Hawaiian eruptions are a type of volcanic eruption named after the Hawaiian volcanoes with which this eruptive type is hallmark. Hawaiian eruptions are the calmest types of volcanic events, characterized by the effusive eruption of very fluid basalt-type lavas with low gaseous content. The volume of ejected material from Hawaiian eruptions is less than half of that found in other eruptive types. Steady production of small amounts of lava builds upwardly the big, broad course of a shield volcano. Eruptions are not centralized at the main summit equally with other volcanic types, and often occur at vents around the summit and from fissure vents radiating out of the middle.^[4]

Hawaiian eruptions often begin as a line of vent eruptions forth a fissure vent, a then-called "mantle of fire." These die downward every bit the lava begins to concentrate at a few of the vents. Cardinal-vent eruptions, meanwhile, ofttimes take the form of large lava fountains (both continuous and desultory), which tin can reach heights of hundreds of meters or more. The particles from lava fountains unremarkably cool in the air before striking the footing, resulting in the accumulation of cindery scoria fragments; however, when the air is particularly thick with clasts, they cannot absurd off fast enough due to the surrounding heat, and hit the footing still hot, the accumulation of which forms spatter cones. If eruptive rates are loftier enough, they may even class 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 germination of active lava lakes, cocky-maintaining pools of raw lava with a thin chaff of semi-cooled rock.^[iv]

Flows from Hawaiian eruptions are basaltic, and tin can be divided into two types past their structural characteristics. Pahoehoe lava is a relatively smooth lava flow that tin be bouncing or ropey. They can move as 1 sail, by the advancement of "toes," or as a snaking lava cavalcade.^[10] A'a lava flows are denser and more gummy than pahoehoe, and tend to move slower. Flows tin can measure out 2 to twenty m (7 to 66 ft) thick. A'a flows are so thick that the outside layers cools into a rubble-like mass, insulating the still-hot interior and preventing it from cooling. A'a lava moves in a peculiar manner—the front of the menses steepens due to pressure from behind until information technology breaks off, afterward which the general mass backside it moves forward. Pahoehoe lava can sometimes go A'a lava due to increasing viscosity or increasing rate of shear, but A'a lava never turns into pahoehoe period.^[11]

Hawaiian eruptions are responsible for several unique volcanological objects. Small volcanic particles are carried and formed by the current of air, chilling quickly into teardrop-shaped glassy fragments known as Pele'southward tears (after Pele, the Hawaiian volcano deity). During especially high winds these chunks may fifty-fifty accept the course of long drawn-out strands, known as Pele'south hair. Sometimes basalt aerates into reticulite, the everyman density rock type on earth.^[4]

Although Hawaiian eruptions are named after the volcanoes of Hawaii, they are not necessarily restricted to them; the largest lava fountain ever recorded formed on the island of Izu Ōshima (on Mount Mihara) in 1986, a 1,600 m (5,249 ft) gusher that was more than than twice as high as the mountain itself (which stands at 764 m (2,507 ft)).^{[4] [12]}

Volcanoes known to have Hawaiian activeness 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 (4 mi)-long crevice-based "mantle of fire" on 3 January 1983. These gave way to centralized eruptions on the site of Kilauea's east rift, eventually building up the cone.^[four]
• For a list of all of the volcanoes of Hawaii, meet List of volcanoes in the Hawaiian – Emperor seamount chain.
• Mount Etna, Italia.^[4]
• Mountain Mihara in 1986 (encounter in a higher place paragraph)^[four]

Strombolian [edit]

Strombolian eruptions are a blazon of volcanic eruption named after 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 accumulate and coalesce into large bubbles, called gas slugs. These abound large enough to rise through the lava column.^[xiv] Upon reaching the surface, the divergence in air pressure causes the bubble to burst with a loud popular,^[thirteen] 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.^[13] During eruptions, these blasts occur as often equally every few minutes.^[15]

The term "Strombolian" has been used indiscriminately to depict a broad variety of volcanic eruptions, varying from modest volcanic blasts to large eruptive columns. In reality, true Strombolian eruptions are characterized by brusque-lived and explosive eruptions of lavas with intermediate viscosity, often ejected high into the air. Columns tin measure hundreds of meters in elevation. The lavas formed by Strombolian eruptions are a course of relatively sticky basaltic lava, and its end production is mostly scoria.^[13] The relative passivity of Strombolian eruptions, and its non-damaging nature to its source vent allow Strombolian eruptions to go along unabated for thousands of years, and also makes it one of the least dangerous eruptive types.^[15]

An example of the lava arcs formed during Strombolian activity. This paradigm is of Stromboli itself.

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

Strombolian eruptions are similar to Hawaiian eruptions, but there are differences. Strombolian eruptions are noisier, produce no sustained eruptive columns, do non produce some volcanic products associated with Hawaiian volcanism (specifically Pele's tears and Pele's hair), and produce fewer molten lava flows (although the eruptive material does tend to form small rivulets).^{[xiii] [15]}

Volcanoes known to take Strombolian action include:

• Parícutin, Mexico, which erupted from a scissure in a cornfield in 1943. Two years into its life, pyroclastic activity began to wane, and the outpouring of lava from its base became its master mode of activity. Eruptions ceased in 1952, and the concluding superlative was 424 thousand (1,391 ft). This was the first time that scientists are able to notice the complete life cycle of a volcano.^[thirteen]
• Mount Etna, Italian republic, which has displayed Strombolian activity in recent eruptions, for case in 1981, 1999,^[17] 2002–2003, and 2009.^[18]
• Mountain Erebus in Antarctica, the southernmost active volcano in the world, having been observed erupting since 1972.^[19] Eruptive activity at Erebus consists of frequent Strombolian activity.^[20]
• Stromboli itself. The namesake of the mild explosive action that it possesses has been active throughout historical time; substantially continuous Strombolian eruptions, occasionally accompanied by lava flows, have been recorded at Stromboli for more a millennium.^[21]

Vulcanian [edit]

Vulcanian eruptions are a type of volcanic eruption named after the volcano Vulcano.^[22] Information technology was named then following Giuseppe Mercalli's observations of its 1888–1890 eruptions.^[23] In Vulcanian eruptions, intermediate gummy 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, somewhen popping the cap holding the magma downwardly and resulting in an explosive eruption. Even so, unlike Strombolian eruptions, ejected lava fragments are not aerodynamic; this is due to the college viscosity of Vulcanian magma and the greater incorporation of crystalline material cleaved off from the former cap. They are also more explosive than their Strombolian counterparts, with eruptive columns often reaching between 5 and 10 km (3 and half-dozen mi) high. Lastly, Vulcanian deposits are andesitic to dacitic rather than basaltic.^[22]

Initial Vulcanian activity is characterized by a series of short-lived explosions, lasting a few minutes to a few hours and typified by the ejection of volcanic bombs and blocks. These eruptions wear downward the lava dome belongings the magma down, and it disintegrates, leading to much more 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 downward the volcano's slope.^[22]

Deposits nearly the source vent consist of large volcanic blocks and bombs, with and so-called "bread-crust bombs" being specially mutual. These deeply cracked volcanic chunks form when the exterior of ejected lava cools quickly into a glassy or fine-grained shell, but the within continues to cool and vesiculate. The eye of the fragment expands, cracking the exterior. Nonetheless 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 event of high gas contents inside the magma. In some cases these have been found to be the result of interaction with meteoric water, suggesting that Vulcanian eruptions are partially hydrovolcanic.^[22]

Volcanoes that have exhibited Vulcanian activity include:

• Sakurajima, Japan has been the site of Vulcanian action almost-continuously since 1955.^[24]
• Tavurvur, Papua New Guinea, i 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 up at least half of all known Holocene eruptions.^[26]

Peléan [edit]

Peléan eruptions (or nuée ardente) are a blazon of volcanic eruption named subsequently the volcano Mount 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 corporeality of gas, dust, ash, and lava fragments are blown out the volcano'southward central crater,^[27] driven by the plummet of rhyolite, dacite, and andesite lava dome collapses that oftentimes create large eruptive columns. An early sign of a coming eruption is the growth of a so-chosen Peléan or lava spine, a bulge in the volcano'southward summit preempting its total collapse.^[28] The material collapses upon itself, forming a fast-moving pyroclastic menses^[27] (known as a block-and-ash flow)^[29] that moves down the side of the mountain at tremendous speeds, often over 150 km (93 mi) per hour. These landslides make Peléan eruptions one of the most dangerous in the earth, capable of tearing through populated areas and causing serious loss of life. The 1902 eruption of Mount Pelée caused tremendous destruction, killing more than 30,000 people and completely destroying St. Pierre, the worst volcanic event in the 20th century.^[27]

Peléan eruptions are characterized most prominently by the incandescent pyroclastic flows that they drive. 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, hence the eruption occurs as one large explosion rather than several smaller ones.^[xxx]

Volcanoes known to have Peléan activity include:

• Mount Pelée, Martinique. The 1902 eruption of Mount Pelée completely devastated the island, destroying St. Pierre and leaving simply 3 survivors.^[31] The eruption was directly preceded by lava dome growth.^[22]
• Mayon Volcano, the Philippines near active volcano. Information technology has been the site of many unlike types of eruptions, Peléan included. Approximately xl ravines radiate from the acme and provide pathways for frequent pyroclastic flows and mudflows to the lowlands below. Mayon'southward almost violent eruption occurred in 1814 and was responsible for over 1200 deaths.^[32]
• The 1951 Peléan eruption of Mountain Lamington. Prior to this eruption the peak had not even been recognized as a volcano. Over 3,000 people were killed, and it has go a criterion 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 Mountain Vesuvius in 79 AD that cached the Roman towns of Pompeii and Herculaneum and, specifically, for its chronicler Pliny the Younger.^[34] The procedure 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 in one case they accomplish a certain size (almost 75% of the total volume of the magma conduit) they explode. The narrow confines of the conduit force the gases and associated magma up, forming an eruptive column. Eruption velocity is controlled by the gas contents of the column, and low-strength surface rocks normally crevice under the force per unit area of the eruption, forming a flared outgoing construction that pushes the gases even faster.^[35]

These massive eruptive columns are the distinctive feature of a Plinian eruption, and achieve upwards 2 to 45 km (one to 28 mi) into the atmosphere. The densest part of the feather, direct above 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 information technology even further up into the stratosphere. At the top of the plume, powerful prevailing winds drive the plume in a direction away from the volcano.^[35]

These highly explosive eruptions are usually associated with volatile-rich dacitic to rhyolitic lavas, and occur most typically at stratovolcanoes. Eruptions can final anywhere from hours to days, with longer eruptions being associated with more felsic volcanoes. Although they are commonly 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 rapidly.^[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 as well similar to Hawaiian lava fountains in that both eruptive types produce sustained eruption columns maintained by the growth of bubbles that move up at almost the same speed as the magma surrounding them.^[34]

Regions affected by Plinian eruptions are subjected to heavy pumice airfall affecting an expanse 0.5 to 50 km^three (0 to 12 cu mi) in size.^[34] The material in the ash plume eventually finds its style back to the basis, covering the landscape in a thick layer of many cubic kilometers of ash.^[37]

Nonetheless the about dangerous eruptive feature are the pyroclastic flows generated by textile collapse, which motility downwardly the side of the mountain at farthermost speeds^[34] of up to 700 km (435 mi) per hr 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 form lahars, fast moving mudflows with the consistency of wet concrete that move at the speed of a river rapid.^[34]

Major Plinian eruptive events include:

• The AD 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 final eruption was in 1944 and caused problems for the allied armies as they advanced through Italy.^[34] It was the gimmicky report past 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'due south elevation, was a Plinian eruption of Volcanic Explosivity Index (VEI) 5.^[3]
• The strongest types of eruptions, with a VEI of 8, are and then-called "Ultra-Plinian" eruptions, such as the 1 at Lake Toba 74 thousand years ago, which put out 2800 times the material erupted by Mount St. Helens in 1980.^{[seven] [39]}
• Hekla in Iceland, an example of basaltic Plinian volcanism being its 1947–48 eruption. The past 800 years accept been a pattern of violent initial eruptions of pumice followed by prolonged extrusion of basaltic lava from the lower part of the volcano.^[34]
• Pinatubo in the Philippines on xv June 1991, which produced 5 km³ (1 cu mi) of dacitic magma, a 40 km (25 mi) high eruption column, and released 17 megatons of sulfur dioxide.^[40]

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 h2o (as distinguished from magmatic eruptions, which are driven by thermal expansion).^{[ clarification needed ]} This temperature difference between the 2 causes violent h2o-lava interactions that make up the eruption. The products of phreatomagmatic eruptions are believed to exist more regular in shape and finer grained than the products of magmatic eruptions because of the differences in eruptive mechanisms.^{[i] [41]}

There is debate about the exact 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 fabric past propagating stress waves, widening cracks and increasing surface surface area that ultimately leads to rapid cooling and explosive contraction-driven eruptions.^[1]

Surtseyan [edit]

A Surtseyan (or hydrovolcanic) eruption is a type of volcanic eruption characterized by shallow-water interactions between water and lava, named afterwards its about famous example, the eruption and germination of the isle of Surtsey off the coast of Republic of iceland in 1963. Surtseyan eruptions are the "wet" equivalent of ground-based Strombolian eruptions, but because they take place in water they are much more than explosive. As h2o is heated past lava, it flashes into steam and expands violently, fragmenting the magma it contacts into fine-grained ash. Surtseyan eruptions are typical of shallow-water volcanic oceanic islands, just they are not confined to seamounts. They can happen on land besides, where rising magma that comes into contact with an aquifer (water-begetting rock formation) at shallow levels under the volcano tin can cause them.^[5] The products of Surtseyan eruptions are generally 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 by the gravitational collapse of a vaporous eruptive column, one that is denser overall than a regular volcanic column. The densest part of the deject 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 past bomb sags, rock that was flung out by the explosive eruption and followed a ballistic path to the ground. Accumulations of wet, spherical ash known as accretionary lapilli are another common surge indicator.^[v]

Over time Surtseyan eruptions tend to form maars, wide low-relief volcanic craters dug into the ground, and tuff rings, circular structures built of chop-chop quenched lava. These structures are associated with single vent eruptions. Even so, if eruptions arise along fracture zones, rift zones may be 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.^{[5] [42]} Littoral cones are another hydrovolcanic feature, generated past the explosive deposition of basaltic tephra (although they are not truly volcanic vents). They form when lava accumulates within cracks in lava, superheats and explodes in a steam explosion, breaking the rock apart and depositing it on the volcano's flank. Consecutive explosions of this blazon eventually generate the cone.^[5]

Volcanoes known to have Surtseyan activity include:

• Surtsey, Republic of iceland. The volcano congenital itself upwardly from depth and emerged to a higher place the Atlantic Ocean off the declension of Iceland in 1963. Initial hydrovolcanics were highly explosive, merely every bit the volcano grew, rising lava interacted less with water and more than with air, until finally Surtseyan activity waned and became more Strombolian.^[5]
• Ukinrek Maars in Alaska, 1977, and Capelinhos in the Azores, 1957, both examples of above-water Surtseyan activity.^[5]
• Mount Tarawera in New Zealand erupted along a rift zone in 1886, killing 150 people.^[5]
• Ferdinandea, a seamount in the Mediterranean Ocean, breached sea level in July 1831 and caused a sovereignty dispute between Italy, French republic, and Great Britain. The volcano did non build tuff cones strong plenty to withstand erosion and before long disappeared back below the waves.^[43]
• The underwater volcano Hunga Tonga in Tonga breached sea level in 2009. Both of its vents exhibited Surtseyan activeness for much of the time. It was also the site of an earlier eruption in May 1988.^[44]

• 

  Surtsey, erupting 13 days after breaching the water. A tuff band surrounds the vent.

Submarine [edit]

Submarine eruptions are a type of volcanic eruption that occurs underwater. An estimated 75% of the total volcanic eruptive volume is generated by submarine eruptions near mid ocean ridges alone, however because of the bug associated with detecting deep sea volcanics, they remained about unknown until advances in the 1990s made it possible to detect them.^[45]

Submarine eruptions may produce seamounts which may intermission the surface to form volcanic islands and island bondage.

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

Spreading rates along mid-ocean ridges vary widely, from 2 cm (0.8 in) per year at the Mid-Atlantic Ridge, to upwardly to 16 cm (six in) along the Eastward Pacific Ascension. College spreading rates are a probable crusade for higher levels of volcanism. The engineering for studying seamount eruptions did not be until advancements in hydrophone applied science made it possible to "listen" to acoustic waves, known equally T-waves, released by submarine earthquakes associated with submarine volcanic eruptions. The reason for this is that land-based seismometers cannot detect body of water-based earthquakes beneath a magnitude of iv, but acoustic waves travel well in water and over long periods of time. A organization in the Due north Pacific, maintained by the The states Navy and originally intended for the detection of submarines, has detected an event on average every 2 to 3 years.^[45]

The most common underwater catamenia is pillow lava, a circular lava flow named after its unusual shape. Less common are glassy, marginal canvass flows, indicative of larger-scale flows. Volcaniclastic sedimentary rocks are mutual in shallow-h2o environments. As plate motion starts to carry the volcanoes away from their eruptive source, eruption rates first to die down, and water erosion grinds the volcano downward. The concluding stages of eruption cap the seamount in alkalic flows.^[46] At that place are about 100,000 deepwater volcanoes in the world,^[47] although nigh are across the active stage 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 by interactions betwixt lava and ice, often nether a glacier. The nature of glaciovolcanism dictates that it occurs at areas of high breadth and high altitude.^[48] It has been suggested that subglacial volcanoes that are not actively erupting often dump heat into the ice roofing them, producing meltwater.^[49] This meltwater mix means that subglacial eruptions oft generate dangerous jökulhlaups (floods) and lahars.^[48]

The study of glaciovolcanism is still a relatively new field. Early accounts described the unusual flat-topped steep-sided volcanoes (chosen tuyas) in Republic of iceland that were suggested to have formed from eruptions below ice. The first English-language paper on the discipline was published in 1947 by William Henry Mathews, describing the Tuya Butte field in northwest British Columbia, Canada. The eruptive process that builds these structures, originally inferred in the paper,^[48] begins with volcanic growth beneath the glacier. At start the eruptions resemble those that occur in the deep ocean, forming piles of pillow lava at the base of the volcanic structure. Some of the lava shatters when information technology comes in contact with the cold ice, forming a glassy breccia called hyaloclastite. After a while the ice finally melts into a lake, and the more explosive eruptions of Surtseyan activity begins, building upward flanks made up of mostly hyaloclastite. Eventually the lake boils off from continued volcanism, and the lava flows become more effusive and thicken every bit the lava cools much more slowly, oft forming columnar jointing. Well-preserved tuyas show all of these stages, for example Hjorleifshofdi in Iceland.^[50]

Products of volcano-water ice interactions stand as diverse structures, whose shape is dependent on complex eruptive and environmental interactions. Glacial volcanism is a expert indicator of past ice distribution, making information technology an important climatic marker. Since they are embedded in ice, equally glacial water ice retreats worldwide there are concerns that tuyas and other structures may destabilize, resulting in mass landslides. Show of volcanic-glacial interactions are axiomatic in Iceland and parts of British Columbia, and it 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.S. states of Hawaii and Alaska, the Pour Range of western North America, S America and even on the planet Mars.^[48] Volcanoes known to have subglacial activity include:

• Mauna Kea in tropical Hawaii. There is show of by subglacial eruptive activeness on the volcano in the form of a subglacial eolith on its summit. The eruptions originated near 10,000 years ago, during the last ice age, when the summit of Mauna Kea was covered in water ice.^[51]
• In 2008, the British Antarctic Survey reported a volcanic eruption under the Antarctica water ice sheet two,200 years ago. Information technology is believed to exist that this was the biggest eruption in Antarctica in the terminal 10,000 years. Volcanic ash deposits from the volcano were identified through an airborne radar survey, buried under subsequently snowfalls in the Hudson Mountains, close to Pine Island Glacier.^[49]
• Republic of iceland, well known for both glaciers and volcanoes, is often a site of subglacial eruptions. An example an eruption under the Vatnajökull water ice cap in 1996, which occurred nether an estimated 2,500 ft (762 thousand) of ice.^[52]
• Every bit part of the search for life on Mars, scientists have suggested that there may be subglacial volcanoes on the ruby planet. Several potential sites of such volcanism have been reviewed, and compared extensively with similar features in Iceland:^[53]

Viable microbial communities have been found living in deep (−2800 m) geothermal groundwater at 349 K and pressures >300 bar. Furthermore, microbes take been postulated to exist in basaltic rocks in rinds of contradistinct volcanic glass. All of these weather 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 cold ground or surface water come up into contact with hot rock or magma it superheats and explodes, fracturing the surrounding stone^[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 only blast out fragments of pre-existing solid rock from the volcanic conduit; no new magma is erupted.^[56] Because they are driven by the cracking of stone strata under pressure, phreatic activity does not always effect in an eruption; if the rock face is strong enough to withstand the explosive force, outright eruptions may not occur, although cracks in the rock volition probably develop and weaken it, furthering hereafter eruptions.^[54]

Often a precursor of future volcanic activity,^[57] phreatic eruptions are generally weak, although at that place take been exceptions.^[56] Some phreatic events may exist triggered by earthquake activity, another volcanic forerunner, and they may also travel along dike lines.^[54] Phreatic eruptions course base surges, lahars, avalanches, and volcanic block "rain." They may also release mortiferous toxic gas able to suffocate anyone in range of the eruption.^[57]

Volcanoes known to exhibit phreatic activity include:

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

See as well [edit]

• List of large volcanic eruptions in the 21st century
• List of Quaternary volcanic eruptions
• Prediction of volcanic action
• Timeline of volcanism on Globe – Wikipedia list article

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Further reading [edit]

morinclan1973.blogspot.com

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

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