http://en.wikipedia.org/wiki/Volcano i don't see how that doesn't help. http://volcano.und.edu/vwdocs/frequent_questions/grp8/question800.html

I'm not sure about the tallest Volcano... But I know about how they erupt. Well imagine this: as tectonic plates are being submerged (due to convectional currents in the magma underneath transporting them slowly. The thinner tectonic plates get pushed under the thicker plates into the mantle), the rock that composes the tectonic plate will melt because of the extreme heat in the mantle. It becomes magma. So, imagine the huge ammount of magma under a realtively thin layer of rock. The pressure's going to rise and all that extra magma has to go somewhere. The only place is up. That's when you get a volcanic eruption or formation. The consistency of the magma can differ, but that's another topic. The more magma pressure there is under the crust, the more explosive the erruption will be. Of course, there are more things than lava released. (Lava is just magma that is above the surface) Hope that's of some help. That's just the basics.

The tallest volcano on Earth is Ojos del Salado* which is about 22,600 feet tall. The tallest known mountain in our solar system is the Martian volcano Olympus Mons which I've heard is about 90,000 feet tall and has a base diameter of about 335 miles. *Per Seraphim's source.

The tallest volcano on Earth measured from it's base on the sea floor is Mauna Loa on the Island of Hawaii. It is 16km tall. That's 135,951ft high. Actually, Mauna Loa is the biggest thing on the planet.

A) Dont Use Wikipedia. You Can Change The Info On It To Something Blah. I Had Some Freinds Do That. B) If I Remember Correctly A Volcan Erupts From The Pressure Of Lava Pushing On It. C) The Tallest Still Active Valcano is In Hawii I Think. D) A Volcano Is Formed At First By A Puddle Of Lava. Over The Years The Puddle Gets Taller And Wider As More Lava Erupts. Thus Making The Valcano. PS The Lava Is From The Center Of The Earth Incase You Wanted To Know.

Volcanoes erupt when molten rock, deep in the Earth's Crust or in the upper mantle, called magma builds up sufficient pressure to fracture the overlying rock and release the magma to erupt at the surface.... or, when fracturing or rifting of the Earth's crust reduces rock pressure at depths where stable solid minerals melt in consequence of the pressure drop, forming magma which then rises and erupts through the ready conduits to the surface. This occurs in several different ways in different parts of the world, giving rise to different types of magma and different types of volcano. Magma from the Earth's upper mantle is basic in composition with a high proportion of Ferro-magnesian minerals. These are the minerals that are stable at the high temperatures found in the mantle. Basic magmas are generally the hottest and most fluid, and they erupt readily and rapidly to the surface, through open faults and fissures in the overlying rock. All the submarine volcanoes along the mid-oceanic ridges and most island volcanoes and rift-valley volcanoes are of this type. They erupt frequently and freely, producing cinder cones, ash and fast-flowing lava. Frequent copious eruptions over a long period of time build up thick basalt plateaux such as those of Oregon and Washington States(USA), Sierra Madre Occidental (Mexico),Iceland, Northern Ireland, The Ethiopian Highlands, Lesotho (S. Africa), Syria's Golan Heights, and the vast Deccan Plateau in India. In subduction zones where oceanic crust is forced under continental margins magma is created from volcanic basement mixed with some ocean floor sediments and sea water, forming a more volatile mixture. This magma collects in large magma chambers, sometimes many miles in diameter, that are trapped beneath the thick continental crust. Eruptions from newly formed magma chambers produce basic volcanic eruptions too, and the characteristic rock that forms from the erupted lavas is known as Andesite, after the Andes mountains. Often, however, the magma does not reach the surface readily, and may build up deep beneath the surface for hundreds or thousands of years, evolving in consistency as more and more of the continental rock is assimilated into the 'melting pot'. This happens usually by collapse of the roof zone of the magma chamber, which by degrees allows the magma to work its way towards the surface. As it rises it cools slowly and some of the minerals that have a high melting point crystallise out of the mix in a process called magmatic fractionation. Magma thus becomes increasingly acidic and enriched in Silica, Calcium, sodium and potassium and volatile components like Corbon, Sulphur, Nitrogen, and Water. Acid magmas form rocks such as Granodiorite, Granite, Felsite, and Syenite. They are cooler and more viscous than basic magmas. They do not erupt easily and eruptions are infrequent. Outlets are usually plugged by crystallised lava and explosive eruptions are characteristic. Catastrophic explosive eruptions such as Vesuvius (Italy), Krakatoa (Indonesia), Mont Pelee (Martinique), and Mount St Helens (USA) are of this type. Wikipedia gives an authoratative answer on the world's highest volcano. Ojos del Salado is a massive stratovolcano in the Andes on the Argentina-Chile border and the highest volcano in the world at 6,891 metres (22,608 ft). It is also the second highest mountain in the Western Hemisphere and the highest in Chile. It is located about 600 kilometres (370 mi) north of Aconcagua (not a volcano), the highest mountain in the Western Hemisphere at 6,962 m (22,841 ft). Due to its location near the Atacama desert, the mountain has very dry conditions with snow only remaining on the peak during winter. Despite the generally dry conditions, there is a permanent crater lake about 100 metres (300 ft) in diameter at an elevation of 6,390 m (20,960 ft) on the eastern side of Ojos del Salado.[3] This is most likely the highest lake of any kind in the world. Counting height below sea level, however, Hawaii's Mauna Loa is the tallest volcano on Earth. Olympus Mons on Mars is the tallest volcano so far measured in the solar system.