how do volcano plates come together?
85175
There's no such thing as a volcanic plate.\n\nTechtonic plates "float" on the earth's mantle, and most of the earths volcanism occurs where those plates meet.  The motion of these plates is mostly driven by convection currents in the mantle and is beyond the scope of this post.
426456
http://www.geology.sdsu.edu/how_volcanoes_work/subducvolc_page.html\n\nstratovolcanoes\n\nbut on land your answer is probably going to be basaltic
1023902
Key principles\n\nThe key principle of word formation is that the wordsphere exists as separate and distinct letter plates, which float on the fluid-like (visco-elastic liquid) phrasesphere. The relative fluidity of the phrasesphere allows the letter plates to undergo motion in different directions. One plate meets another along a plate boundary.\n\nTypes of plate boundaries\n\nThere are three types of plate boundaries, characterized by the way the plates move relative to each other.\n\n   1. Transform boundaries occur where plates slide, or perhaps more accurately grind, past each other along transform faults. The relative motion of the two plates is either sinistral (left side toward the observer) or dextral (right side toward the observer).\n\n   2. Divergent boundaries occur where two plates slide apart from each other (examples of which can be seen at mid-ocean ridges and active zones of rifting (such as with the East Africa rift)).\n\n   3. Convergent boundaries (or active margins) occur where two plates slide towards each other commonly forming either a subduction zone (if one plate moves underneath the other) or a continental collision (if the two plates contain continental crust). Deep marine trenches are typically associated with subduction zones. Due to friction and heating of the subducting slab volcanism is almost always closely linked. Examples of this are the Andes mountain range in South America and the Japanese island arc.
819002
When two plates collide, they BOTH begin to go under a bit.  However, when a continental, and an oceanic plate collide, the oceanic plate ends up going under more.  Why?\n\nFor one thing, the continental plate is up higher than the oceanic plate to begin with.  After all, continental plates are always above sea level, and oceanic plates are always below sea level.  With the advantage of heighth, the continental plate usually pushes the oceanic plate below.\n\nFor another thing, the continental plate is thicker than the oceanic plate, and therefore is going to be harder to crumple, squish, or flatten.\n\nAlso, the oceanic plate is already under an enormous downward pressure from all of the ocean on top of it.\n\nAdditionally, continental plates are lighter.  They were formed by materials on the primordial earth that had floated to the surface, while oceanic plates are formed out of the magma from the center of the earth, which was below the continental plates because it was heavier at the time the plates were forming.\n\nAnd finally, wet rocks are a great deal softer than drier rocks, so the continental plate is harder to bend or break than the oceanic plate, which is soaked all the way through.
846532
There are several processes in Plate Tectonics that cause volcanism, but they result in two main types of volcanism.\n\nVolcanism in subduction is caused by volitals, like H2O, CO2. These are carried down by the plate, mainly in the form of weak minerals. These minerals break down with pressure and temperature into stronger minerals that don't contain water and carbon dioxide. The leftover gases and liquids travel into the mantle (the mantle wedge) and hydrate the mantle, causing melting. The melt rises and then... volcano!\n\nThe other main cause is from rising mantle material, which forms decompression melting. Basically, hot mantle is kept from melting by the pressure of the earth at depth. When this material rises, the pressure drops much faster than the temperature, and thus it partially melts. This mainly occurs at divergent boundaries and hot spots, which are areas in plate tectonics that have rising materials or spreading.\n\nBy the way, as far as scientists know, the largest ever was the 27.8 Ma eruption of the Fish Canyon Tuff at La Garita in Colorado, estimated at 3,000 - 5,000 cubic km.\n\nTambora in 1815 was the largest in recorded history, 100 cubic km.
550913
Answer two is right in that it would be igneous (all volcanic rocks are igneous).  What is normally seen at a convergent boundary is an igneous rock that is Andesitic (Andesite).  This is produced from lava that has a relatively high level of silica.  These rocks were initially identified on the slopes of the Andes Mountains (that's why its called Andesite) due to the portion of the pacific plat that is subducting under South America.
839321
The mechanisms of tectonic plate movement is quite complex, but in its simplest terms, tectonic plates float on molten magma of the earth's interior. Convection currents within the molten magma behave similarly to convection currents in a pan of water being heated on the stove. Water on the bottom of the pan is heated and begins to rise because it is slightly less dense than the cooler water on the top. The cooler is slightly more dense and begins to sink. As this water is heated, it begins to rise, thus a convection movement or convection current is created in the water in the pan. \n\nMagma is far more dense than water and is much hotter, but it is still a fluid. Magma near the core is hotter than the magma beneath the crust. Hotter magma moves up, cooler magma moves down, very very very slowly, but none the less, it moves. The crust, a.k.a. tectonic plates float on the magma. Float some pieces of Styrofoam on the water in the pan. What happens? The foam moves around by the convection forces in the water.  Tectonic plates do the same thing. Its just not as fast.\n\nHope this helps.
147972
Water.\n\nWater is one of the key parts of the formation of magma in subduction zones. The water that is in the subducting plate lowers the melting point of the rock by a few hundred degrees C. The water in the subduction plate will boil and migrate upwards into the overlying wedge of mantle rock where it will reduce the melting point of the overlying mantle. This magma will migrate upwards and form a volcano. \n\nAnother part of this process is that within rock there are many different minerals, all with different melting points, so the ones that melt at the lowest temperatures tend to form magma first, so the resulting magma comes from a partial melt of the source rock.\n\nHere's another diagram (I'd draw you my own but I can't post anything but text here):\nhttp://earth.leeds.ac.uk/dynamicearth/subduction/cordillera_islandarc.htm
940856
http://www.cet.edu/ete/modules/msese/earthsysflr/plates1.html has some good diagrams or http://www.geology.sdsu.edu/how_volcanoes_work/ are two very good websites for simple diagrams.
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.
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.
344523
Well, yeah, there is a relationship.  Most of our recent volcanoes occur near the boundaries of plates.  At mid-ocean ridges hot magma is welling up and cooling to make the plates on either side larger.  Iceland, with its many volcanoes, is on the Mid-Atlantic Ridge.  Where oceanic plates are pushed under other plates (subducted), they are forced deeper into earth where it's hotter, and the subducted plate tends to melt.  The lighter parts of the melt try to work their way toward the surface (because they're less dense, and, hence buoyant), and cause volcanoes such as those of the Pacific's Ring of Fire--Indonesian volcanoes, Japanese volcanoes such as Mount Fuji, Alaska's volcanoes, the Cascade Range in Washington State, and so on.\n\nSome volcanoes are associated with "hot spots", where a plume of magma flows toward the surface, but is not associated with a plate boundary.  The Hawaiian Islands are an example of such a hot spot.  Plate tectonics also affect things here.  The plate moves over the hot spot, continually making new islands.  The newest one hasn't reached the surface yet.  Hawai'i is the newest one that's above the surface, and as you move north and west along the Hawai'ian Archipelago, the islands are progressively older and, because they've had more time to be eroded, smaller.  Northwest of the archipelago are the Emperor Seamounts, islands that were eroded until they no longer reach the ocean's surface.
71801
It depends on the volcano.\n\nIf magma - molten rock - is erupted it forms new formations when it cools. On the big island of Hawaii, the volcanic eruptions have added a lot of new land to the island.\n\nIf it is a pyroclastic flow - fast, hot gasses and volcanic debris -  like the one that destroyed Pompeii or Mt. St. Helens, there may not be any new land created and the existing land will be radically altered.\n\nIn general, when a land based volcano erupts, the lava and stone and ash build up around the eruption site into a cone shape.\n\nUndersea volcanos spweing lava also build up, but not in a cone shape. Once the hot rock hits water it starts to cool into large pillow-shaped forms.
836192
The Earth is formed of several layers that have very different physical and chemical properties. The outer layer, which averages about 70 kilometers in thickness, consists of about a dozen large, irregularly shaped plates that slide over, under and past each other on top of the partly molten inner layer. Most earthquakes occur at the boundaries where the plates meet. In fact, the locations of earthquakes and the kinds of ruptures they produce help scientists define the plate boundaries. \nThere are three types of plate boundaries: spreading zones, transform faults, and subduction zones. At spreading zones, molten rock rises, pushing two plates apart and adding new material at their edges. Most spreading zones are found in oceans; for example, the North American and Eurasian plates are spreading apart along the mid-Atlantic ridge. Spreading zones usually have earthquakes at shallow depths (within 30 kilometers of the surface).  \n\nTransform faults are found where plates slide past one another. An example of a transform-fault plate boundary is the San Andreas fault, along the coast of California and northwestern Mexico. Earthquakes at transform faults tend to occur at shallow depths and form fairly straight linear patterns. \n\nSubduction zones are found where one plate overrides, or subducts, another, pushing it downward into the mantle where it melts. An example of a subduction-zone plate boundary is found along the northwest coast of the United States, western Canada, and southern Alaska and the Aleutian Islands. Subduction zones are characterized by deep-ocean trenches, shallow to deep earthquakes, and mountain ranges containing active volcanoes.\n\nEarthquakes can also occur within plates, although plate-boundary earthquakes are much more common. Less than 10 percent of all earthquakes occur within plate interiors. As plates continue to move and plate boundaries change over geologic time, weakened boundary regions become part of the interiors of the plates. These zones of weakness within the continents can cause earthquakes in response to stresses that originate at the edges of the plate or in the deeper crust. The New Madrid earthquakes of 1811-1812 and the 1886 Charleston earthquake occurred within the North American plate.
134315
There are a couple ways. Hot spots can build up islands through volcanic activity, like Hawaii. Some islands can be created by subduction volcanism (Japan). Other islands can be uplifted at convergent or possibly transverse plate boundaries.\n\nIslands can also be created by erosion and inundation, as in a case of sea level rise where the water covers low lying areas while higher areas get "separated" from the land by water (St. Lawrence Island in Alaska). Glaciers can scour channels around large land masses, then recede and the channels can become filled with water to surround the land masses and make them islands. Manhattan Island was actually created by a continental glacier pushing a bunch of sediment out into the ocean and then receeding (it is a moraine).\n\nSome islands can be created purely by sediment deposition, such as those at the mouths of deltas.
542253
by following this recipe:\nhttp://hometown.aol.com/ckckside/reports/volcanoes/vol10.htm
271398
There are lots of connections between volcanoes and earthquakes. Some are direction and indirect. Some comments:\n\n1. Sometimes the collapse of volcanic magma chambers can produce small earthquakes.\n\n2. Earthquakes are mainly caused by the rubbing of tectonic plates against each other as they move. As the tectonic plates move, the edges of some plates are pushed under others. This is called subduction. The melting of the subducted plate can produce volcanism. \n\n3. There are many volcanoes and earthquakes around the so-called "ring of fire" in the Pacific region. This is caused by the movement  of the Pacific tectonic plate.\n\n4. When tectonic plates form at spreading centers, usually under the ocean, magma wells up from below to make new plates. This is related to volcanism. The volcanoes in Iceland are all related to this phenomenon. \n\n5. As plates move over volcanic hotspots, the hot material rising from below can "punch through" the tectonic plate to make a volcanoe. For example, look at the Hawaii-Emperor chain of volcanic islands. As one moves backwards along the chain (which has a mysterious sharp bend in it, when the plate movement changed direction presumably), the islands get older and older. \n\n6. A volcano that forms, creates a large weight on a volcanic plate can sometimes cause it to flex and deform, causing tiny earthquakes in some cases.