Shield volcanoes are the result of high magma supply rates; the lava is hot and little-changed since the time it was generated. Shield volcanoes are the common product of hotspot volcanism but they can also be found along subduction-related volcanic arcs or all by themselves. Jan 14, · Eruptions from shield volcanoes usually involve lava traveling great distances and spreading out into thin sheets. As a result, the volcanic mountain that is built up over time by repeated flows of lava has a broad gently profile sloping away from a .
A shield volcano is what comes out of a shield volcano type of volcano named for its low profile, resembling a warrior 's shield lying on the ground. It is formed by the eruption of highly fluid low shjeld lavawhich travels farther and forms comrs flows than the more viscous co,es erupted from a stratovolcano.
Repeated eruptions results in the steady accumulation of broad sheets of lava, building up the shield volcano's distinctive form. Shield volcanoes are found wherever fluid low- silica lava reaches the surface of the Earth. However, they are most characteristic of ocean island volcanism associated with hot spots or with continental rift s. The term 'shield volcano' is taken from the Knight online how to upgrade term Schildvulkancoined by the Austrian geologist Eduard Suess in and which had been commes into English by Shield volcanoes are distinguished from the three shisld major volcanic types— stratovolcanoeslava domesand cinder cones —by their structural form, a consequence of their particular magmatic composition.
Of these four forms, shield volcanoes oit the least viscous lavas. Whereas stratovolcanoes and lava domes are the product of highly viscous flows, and cinder cones are constructed of explosively eruptive tephrashield volcanoes are the product of gentle effusive eruptions of highly fluid lavas that produce, over time, a broad, gently sloped eponymous "shield".
These are eruptive features which occur along linear fissure vents and are distinguished from shield volcanoes by the lack of an identifiable primary eruptive center. Active shield volcanoes experience ojt eruptive activity over extremely long periods of time, resulting in the gradual build-up of edifices that can reach extremely large dimensions.
However, the extents of the volcano have not been confirmed. Ahat height they are typically about one twentieth their width. Rift zones are a prevalent feature on shield volcanoes that is rare on other volcanic types.
The large, decentralized shape of Hawaiian volcanoes as compared to their smaller, symmetrical Icelandic cousins  can be attributed to rift eruptions. This accounts for their asymmetrical shape, whereas Icelandic volcanoes follow a shirld of central eruptions dominated by summit volvanocausing the lava to be more evenly distributed or symmetrical.
These lavas travel a far greater distance than those of other eruptive types before solidifying, forming extremely wide but relatively thin magmatic sheets often less than 1 m 3 ft thick. Also unlike other eruptive types, Hawaiian eruptions often occur at decentralized fissure ventsbeginning with large "curtains of fire" that quickly die down and concentrate at specific locations on the volcano's rift zones.
Central-vent eruptions, meanwhile, often take the form of large lava fountains both continuous and sporadicwhich can reach heights of hundreds of meters or more.
The particles from lava fountains usually cool in the air before hitting the ground, resulting in the accumulation of oout scoria fragments; however, when the air is especially thick with pyroclaststhey cannot cool off fast enough because of the surrounding heat, and hit the ground still hot, accumulating into spatter cones. If eruptive rates are high enough, they may even form splatter-fed lava flows. These lava flows can be anywhere between 2 and 20 m 10 and 70 ft thick. Although most shield volcanoes are by volume almost entirely Hawaiian and basaltic in origin, they vokcano rarely exclusively so.
Some volcanoes, such as Mount Wrangell in Alaska and Cofre voocano Perote in Mexico, exhibit large enough swings in their historical magmatic eruptive characteristics to cast strict categorical assignment in doubt; one shiekd study of de Perote went so far what comes out of a shield volcano to suggest the term "compound shield-like volcano" instead.
The Hawaiian shield volcanoes are not located near any plate boundaries ; the volcanic activity of this island chain is distributed by the movement of the oceanic plate over an upwelling of magma known as a hotspot.
Over millions of years, the tectonic movement that moves continents also creates how long should i run a day to lose weight volcanic trails across the seafloor.
Their lavas are characterized by high levels of sodiumpotassiumand aluminium. Features common in shield volcanism include lava tubes. These structures help further the propagation of lava, as the walls of the tube insulate the lava within.
How to download free adobe reader some shield volcano eruptions, basaltic lava pours out of a long fissure instead voclano a central vent, and shrouds the countryside with a long band of volcanic material in siheld form of a broad plateau. Plateaus of this type exist in Iceland, Washington, Oregon, and Idaho; the most prominent ones are situated along the Snake River in Idaho and the Columbia River in Washington and Oregon, where they have been measured to be over 1 mi 2 km in thickness.
Calderas are a common feature on shkeld volcanoes. They are formed and reformed over the volcano's lifespan. Long eruptive periods form cinder cones, which then collapse over time to form calderas. The calderas are often filled up by progressive eruptions, or formed elsewhere, and this cycle of collapse and regeneration takes place throughout the volcano's lifespan.
Interactions between water and lava at shield volcanoes can cause some eruptions to become hydrovolcanic. These explosive eruptions are drastically different from the usual shield volcanic activity  and are especially prevalent at the waterbound volcanoes of the Hawaiian Isles. A lava lake in the caldera of Erta Alean active shield volcano in Ethiopia. Shield volcanoes are found worldwide. Although shield volcanoes are not usually associated with subductionthey can occur over subduction zones.
Many shield volcanoes are found in ocean basinssuch as Tamu Massif, the world's largest, although they can what is out in system out println found inland as well—East Africa being one example of this. The largest and most prominent shield volcano chain in the world is the Hawaiian—Emperor seamount chain, a chain of hotspot volcanoes in the Pacific Ocean.
The volcanoes follow a distinct evolutionary pattern of growth and death. The youngest part of the chain is Hawaii, where the volcanoes are characterized by frequent rift eruptions, their large size thousands of km 3 in volumeand their rough, decentralized shape. Rift zones are a prominent feature on these volcanoes and fo for their seemingly random volcanic structure.
The chain includes Mauna Loa, a shield volcano which stands 4, m 13, ft above sea level and reaches a further 13 km 8 mi below the waterline and into the crust, approximately 80, km 3 19, cu mi of rock. This platform creates a shallow water depth of to m 1, to 2, ft shiekd the base of the islands, which stretch over a mi km diameter.
Cerro Azul is a shield volcano on the southwestern part of Isabela Island and is one of the most active in the Galapagos, with the volcwno eruption between May and June The Geophysics Institute at the National Polytechnic School in Quito houses an whst team shirld seismologists and volcanologists  co,es responsibility is to monitor Ecuador's numerous active volcanoes in the Andean Volcanic Belt and the Galapagos Islands.
La Cumbre is an active shield volcano on Fernandina Island that has been erupting since April 11, Curiously, they do not form the same volcanic "line" associated with most hotspots. They are not alone in this regard; the Cobb—Eickelberg Seamount chain in the North Pacific is another example of such a delineated chain. In addition, there is no clear pattern of age between the volcanoes, suggesting a complicated, irregular pattern of creation.
How the islands were formed remains a geological mystery, although several theories have been proposed. Located over the Mid-Atlantic Ridgea vocano tectonic plate in the middle of the Atlantic Ocean, Iceland is the site of about volcanoes of various types. The volcanoes are also very narrow in distribution, occurring in two bands in the West and North Volcanic Zones. Like Hawaiian volcanoes, their formation initially begins with several eruptive centers before centralizing and concentrating at a single point.
The coms shield then forms, burying the smaller ones formed by the early eruptions with its lava. The tholeiitic shields tend to be wider and shallower than the picritic shields.
In East Africa, volcanic activity is generated by the development of the East African Rift and from nearby hotspots. Some volcanoes interact with both. Shield volcanoes are found near the rift and off the coast of Africa, although ehield are more common. Although sparsely studied, wat fact that all of its volcanoes are of Holocene age reflects how young how long to trickle charge a motorcycle battery volcanic center is.
The most active shield volcano in Africa how to duplicate sim card of cell phone Nyamuragira. Eruptions at the shield volcano are generally centered within the large summit caldera or on the numerous fissures and cinder cones on the volcano's flanks.
Lava flows from the most recent century extend down the flanks more oc 30 wha 19 mi from the summit, reaching as qhat as Lake Kivu. Erta Ale in Ethiopia is another active shield volcano and one of the few places in the world with a permanent lava lake, which has been active since at leastand possibly since Shield volcanoes are not limited to Earth; they have been found shieod MarsVenusand Jupiter's moon, Io.
The shield volcanoes of Comew are very similar to the shield volcanoes on Earth. On both planets, they have gently sloping flanks, collapse craters along their central structure, and are built of highly fluid lavas. Volcanic features on Mars were observed long before they were first comse in detail during the — Viking mission. The principal difference between the volcanoes of Mars and those on Earth is in terms of size; Martian volcanoes range in size up to 14 mi 23 km high and mi km in diameter, far larger than the 6 mi 10 km high, 74 mi km wide Hawaiian shields.
Venus has over shield volcanoes which are much flatter, with a larger surface area than those found on Earth, some having a diameter of more than km mi. From Wikipedia, the free encyclopedia. Low profile volcano usually formed almost entirely of fluid lava flows.
Flank vent. Magma chamber. Magma plume. Diagram of a Hawaiian eruption. Ash plume shleld. Lava fountain 3. Crater 4. Lava lake 5. Fumaroles 6. Lava flow 7.
Layers of lava and ash 8. Stratum 9. Sill Magma conduit Magma chamber Dike Click for larger version. Main article: List of shield volcanoes. See also: Category:Lists of extraterrestrial mountains. Berlin: Springer. ISBN Journal of Geophysical Research. Earth, Moon, and Planets.
Online Etymology Dictionary. Douglas Harper.
What comes out of a volcano?
Shield volcanoes are formed by lava flows of low viscosity - lava that flows easily. A shield volcano has a broad shape due to having been formed by multiple lava flows. This type of volcano is formed as a result of lava flowing over a period of time. Because there are multiple flow points for the lava, a gently sloping surface is created. The volcano is comprised of four overlapping shield volcanoes, with the youngest, Kakorinya, located over the axis of the East African Rift. Kalolenyang volcano lies west of Kakorinya, and Likaiu West and Likaiu East volcano are located to the ENE. A km-wide summit caldera was formed at Kakorinya volcano about 92, years ago.
Shield volcanoes are the largest volcanoes on Earth that actually look like volcanoes i. The Hawaiian shield volcanoes are the most famous examples. Shield volcanoes are almost exclusively basalt, a type of lava that is very fluid when erupted. For this reason these volcanoes are not steep you can't pile up a fluid that easily runs downhill.
Shield volcanoes are the result of high magma supply rates; the lava is hot and little-changed since the time it was generated. Shield volcanoes are the common product of hotspot volcanism but they can also be found along subduction-related volcanic arcs or all by themselves.
Here are 4 of the volcanoes that comprise the big island of Hawai'i. The photo was taken from near the summit of East Maui volcano EM. These are the largest volcanoes on Earth. This is a vertical air photo of the summit caldera of Mauna Loa volcano North is to the left.
Notice that the caldera is composed of numerous smaller "cookie-cutter" collapses which have coalesced to form the main caldera. Notice also that many of the lava flows dark and light are ' a'a and pahoehoe , respectively have been truncated by the caldera margin. This is an indication that they erupted from the volcano summit when the caldera was full. Collapse since then has produced the present caldera. In this manner of collapsing and filling, calderas come and go throughout the active lifetime of a basaltic volcano.
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