Where are most Shield Volcanoes usually located?
819640
The most common place to find shield volcanoes is over hotspots (such as Hawai'i, the Galapagos, etc.). This is because hotspot magmas are almost always hot basalts and therefore the erupted lavas have low viscosities. Low viscosity lavas cannot be piled up very steeply so they form shield volcanoes.\nSubduction-zone magmas are almost always cooler and they are higher in silica, both qualities that make the lavas more viscous. These magmas are able to pile up into steep domes and additionally make the volcanoes more explosive so that they have a greater percentage of ash. This makes the volcanoes steep strato-cones instead of shields. It isn't impossible to find shield volcanoes along lines of arc volcanoes (for example Masaya in Nicaragua), but it is rare.
590403
heh... are you referring to ecological endangered hotspots or hot spots under plates that cause volcanic activity?\n\nThere are... way to many ecological hot spots particularly in tropical areas in South America, Africa and South Asia.\n\nAs for hot spots associated with plate tectonics, there are many I'm sure but the Hawaiian Island chain is probably the biggest and longest.  Yellowstone wouldn't be a hot spot really, it's pretty close to a plate boundary and it's activity I would think is left over from this.  Hot spots are unusual for continental plates.  It seems like many island chains could have been formed by similar hot spots under ocean plates though.
257876
A string of volcanoes is called a volcanic front or island arc volcanoes.
139985
This from the USGS has all the answers you are looking for:\nhttp://volcanoes.usgs.gov/Products/Pglossary/ShieldVolcano.html\n"Volcanoes with broad, gentle slopes and built by the eruption of fluid basalt lava are called shield volcanoes. Basalt lava tends to build enormous, low-angle cones because it flows across the ground easily and can form lava tubes that enable lava to flow tens of kilometers from an erupting vent with very little cooling. The largest volcanoes on Earth are shield volcanoes. The name comes from a perceived resemblance to the shape of a warrior's shield."\nExamples of shield volcanoes are the volcanoes in the Hawaiian island chain, including Kilauea, Mauna Loa, Haleakala, etc.\nHope this is helpful :-)
463754
Actually Canada IS on the Ring of Fire, which circles the Pacific Ocean more or less.\n\nCanada does have volcanoes on its west cost where the Rockies and Cascades continue north out of the United States.  \n\nYou don't have to be on the Ring of Fire to have volcanoes either, just along an active fault typically.  There are volcanoes all over the world where the plates meet.  Canada doesn't have volcanoes over most of its land though because it is spread across a continental plate which is too thick in the middle to have hot spots (like the Pacific plate does where we see the Hawaiian islands).  Where it meets the Pacific and Juan de Fuca plate in the west though there is enough movement to form mountains and strato volcanoes (like Mt. St. Helens which is not far from Canada, in Washington State).
505229
El Salvador which is located on the "belt of fire" in Central America.  It is a very small country (14, 718 square miles) and it has 14 volcanoes. So that is about one volcano per 1000 square mile. Anywere you go in the country you can see a volcano at all times.
603115
volcanos\ntectonic plates movements
736066
These plates mentioned above float on a sea of lava.  The volcanos that are found along the seams between the plates could actually happen anywhere, but they happen at the seams because there is less resistance to the pressure there.  It's like, there is water throughout all of the pipes in your home, but the most likely place they will develop a leak is at the joints.
50910
Like most of the interior of the earth, the movements and dynamics of magma are poorly understood. However, it is known that an eruption usually follows movement of magma upwards into the solid layer (the earth's crust) beneath a volcano and occupying a magma chamber. Eventually, magma in the chamber is forced upwards and flows out across the planet surface as lava, or the rising magma can heat water in the surrounding landform and cause explosive discharges of steam; either this or escaping gases from the magma can produce forceful ejections of rocks, cinders, volcanic glass, and/or volcanic ash also known as tephra. While always displaying powerful forces, eruptions can vary from effusive to extremely explosive.\n\nMost volcanoes on the land are formed at destructive plate margins: where oceanic crust is forced below the continental crust because oceanic crust is denser than continental crust. As the oceanic crust 'subducts', it is forced into a higher-temperature region called the asthenosphere, and melts. Friction between these moving plates may also be a cause of melting. The reduced density of the melting rock forces the newly formed magma to rise. As the magma rises through weak areas in the continental crust it may eventually erupt as one or more volcanoes. For example, Mount St. Helens is found inland from the margin between the oceanic Juan de Fuca Plate and the continental North American Plate. The oceanic crust is normally a highly-'mafic' (iron and magnesium rich) rock, but as it rises through granitic (more silicic) continental plates, it may cause 'partial melting' of both mantle rocks and the plate rocks, producing magmas of varying silicity. Volcanic arcs forming near subduction zones, on the edges of continental plates, usually form high-silicity (high-viscosity) stratovolcanoes. Examples include the South American Andes and the Cascade range.\n \nA volcano generally presents itself to the imagination as a mountain sending forth from its summit great clouds of smoke with vast sheets of flame. The truth is that a volcano seldom emits either smoke or flame, although various combinations of hydrogen, carbon, oxygen, and sulfur do sometimes ignite. What is mistaken for smoke consists of vast volumes of fine dust (called volcanic ash), mingled with steam and other vapors, chiefly sulfurous. Most of what appears to be flames is the glare from the erupting materials, glowing because of their high temperature; this glare reflects off the clouds of dust and steam, resembling fire.\n\nPerhaps the most conspicuous part of a volcano is the crater, a basin of a roughly circular shape, formed by a vent (or vents) from which magma erupts as gases, lava, and ejecta. A crater can be of large dimensions, and sometimes of vast depth. Very large features of this sort are termed calderas. Some volcanoes consist of a crater alone, with scarcely any mountain at all; but in the majority of cases the crater is situated on top of a mountain (the volcano), which can tower to an enormous height. Volcanoes that terminate in a principal crater are usually of a conical form.\n\nVolcanic cones are usually smaller features composed of loose ash and cinder, with occasional masses of stone which have been tossed violently into the air by the eruptive forces (and are thus called ejecta). Within the crater of a volcano there may be numerous cones from which vapours are continually issuing, with occasional volleys of ashes and stones. In some volcanoes these cones form lower down the mountain, along rift zones or fractures. When the cone is eroded these rifts or lava filled fractures remain as radial near vertical dikes of volcanic rock. For example the radiating dikes at Shiprock in NW New Mexico.
795984
Composite volcanoes/ strato volcanoe.\n\nSome of the Earth's grandest mountains are composite volcanoes--sometimes called stratovolcanoes. They are typically steep-sided, symmetrical cones of large dimension built of alternating layers of lava flows, volcanic ash, cinders, blocks, and bombs and may rise as much as 8,000 feet above their bases. Some of the most conspicuous and beautiful mountains in the world are composite volcanoes, including Mount Fuji in Japan, Mount Cotopaxi in Ecuador, Mount Shasta in California, Mount Hood in Oregon, and Mount St. Helens and Mount Rainier in Washington.\n\n\n**Here is a personal tip my teacher taught us..depending on the plate it's sitting on and the boundary you will know how the plates strike and collide ...in the case of helen think of yr two hands being forced together straight on max pressure eventually your fingers begin to cave and slide up ward together... it looks olmost pointy and cone shaped right? just like St. Helen... This is assuming you know about plates and faults ....Hopefully you do..if bot disregard..
412918
types of volcanoes:\n1. shield\n2. composite/strato\n3. caldera\n4. MORB\n \ntypes of eruptions\n1. Strombolian\n2. Vulcanian \n3. Vesuvian\n4. Pelean\n5. Hawaiian\n6. Hawaian\n7. Icelandic\n8. plinian
957674
The Pacific Ring of Fire is a zone of frequent earthquakes and volcanic eruptions encircling the basin of the Pacific Ocean. In a 40,000 km horseshoe shape, it is associated with a nearly continuous series of oceanic trenches, island arcs, and volcanic mountain ranges and/or plate movements. It is sometimes called the circum-Pacific belt or the circum-Pacific seismic belt.\n\n90% of the world's earthquakes and 81% of the world's largest earthquakes occur along the Ring of Fire. The next most seismic region (5–6% of earthquakes and 17% of the world's largest earthquakes) is the Alpide belt which extends from Java to Sumatra through the Himalayas, the Mediterranean, and out into the Atlantic. The Mid-Atlantic Ridge is the third most prominent earthquake belt.
597381
Geologists generally group volcanoes into four main kinds--cinder cones, composite volcanoes, shield volcanoes, and lava domes. \n\nIn regard to your question, Cinder cones are the simplest type of volcano. They are built from particles and blobs of congealed lava ejected from a single vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as cinders around the vent to form a circular or oval cone. Most cinder cones have a bowl-shaped crater at the summit and rarely rise more than a thousand feet or so above their surroundings. Cinder cones are numerous in western North America as well as throughout other volcanic terrains of the world.\n\nShield volcanoes are built almost entirely of fluid lava flows. Flow after flow pours out in all directions from a central summit vent, or group of vents, building a broad, gently sloping cone of flat, domical shape, with a profile much like that of a warrior's shield. They are built up slowly by the accretion of thousands of highly fluid lava flows called basalt lava that spread widely over great distances, and then cool as thin, gently dipping sheets. Lavas also commonly erupt from vents along fractures (rift zones) that develop on the flanks of the cone. Some of the largest volcanoes in the world are shield volcanoes. In northern California and Oregon, many shield volcanoes have diameters of 3 or 4 miles and heights of 1,500 to 2,000 feet. The Hawaiian Islands are composed of linear chains of these volcanoes including Kilauea and Mauna Loa on the island of Hawaii-- two of the world's most active volcanoes. The floor of the ocean is more than 15,000 feet deep at the bases of the islands. As Mauna Loa, the largest of the shield volcanoes (and also the world's largest active volcano), projects 13,677 feet above sea level, its top is over 28,000 feet above the deep ocean floor.
310350
From the web site link below:\n\nObsidian occurs only where geologic processes create volcanoes and where the chemical composition of the magma is rich in silica. Obsidian-bearing volcanoes are typically located in or near areas of crustal instability or mountain building. In North America, obsidian is found only in localized areas of the West, where the processes of plate tectonics have created geologic conditions favorable to volcanism and the formation of obsidian. Obsidian typically forms near the end of a volcanic cycle and is often associated with domes of volcanic rock, such as the hills of Glass Buttes, Oregon.
24742
There are volcanoes because of the interaction between multiple plate boundaries which causes the magma in the upper mantle (from beneath the crustal lithosphere) to rise, erupt and form lava at the surface.  \n\nVolcanoes tend to occur at either subduction zones, rifts or at hot spots.  Subduction zones are located at convergent oceanic/oceanic or oceanic/continental plate boundaries, where the denser oceanic crust sinks into the mantle beneath the other plate.  The minerals in the subducted slab dehydrates through metamorphic processes, which releases fluids to the mantle wedge to produce the melt (magma), which erupts to form volcanoes.  \n\nFor rifts, during the early stages of continental rifting (where continents are pulled apart because of extensional forces), volcanic activity can occur because crustal extension can allow magma to rise and intrude further up the crust.  Therefore, volcanic activity can occur in such situations.  eg: East African Rift. \n\nIn mid oceanic ridges, the divergent motion of oceanic plates allows mantle material to rise from below.  This tends to form a submarine ridge rather than a volcano.\n\nHowever, volcanoes can occur within the plate.  These are usually called hotspots, where a plume (a plume of anomalously hot magma) rise from deep within the mantle (probably as deep as the core-mantle boundary) to the surface.  These are stationary and therefore, it can leave a trail of volcanoes as the lithospheric plates move over the mantle.  Eg: Hawaii-Emperor seamount chain.
16875
Occurrence\n\nVolcanoes are found in association with midocean ridge systems (see seafloor spreading) and along convergent plate boundaries, such as around the Pacific Ocean's “Ring of Fire” (see plate tectonics), the ring of plate boundaries associated with volcanic island arcs and ocean trenches surrounding the Pacific Ocean. Continental volcanoes are also associated with converging plate boundaries, such as the volcanoes of the Cascade Range along the W coast of the United States. Isolated volcanoes also form in the midocean area of the Pacific apparently unrelated to crustal plate boundaries. These sea mounts and volcanic island chains, such as the Hawaiian chain, may form from rising magma regions called hot spots.
689680
The opening at the top of a volcano is called a crater.\n\nA caldera is where a magma chamber once existed but collapsed during an eruption. Calderas are much larger than craters.