Volcanoes form when magma, a mixture of hot gas and molten rock, flows out of fissures in Earth's crust. The powerful eruption creates vents in the crust, and mountainous formations take shape above ground as molten rock spreads out in layers and gradually cools down. Each successive eruption occurs when more gas and magma accumulate in the vents, building pressure below the crust.Continue Reading
Beneath Earth's outer surface, the fragmented crust layer is made up of tectonic plates that slowly shift position. Steaming magma helps the tectonic plates move and fills the space between the crust and the mantle, an inner layer of Earth. If plates move too far apart, pressurized magma can shoot up through the crust layer and form a volcano. When tectonic plates shift closer and forcefully bump into one another, their edges may be pushed so deep into Earth's interior that the solid rock heats up, turns into melted magma and rises back up through the crust as a volcano.
Every type of volcano has a distinct formation and eruption pattern. Shield volcanoes are shallow, low-lying formations with wide bases. They form when mild, centralized eruptions release lava that quickly spreads out in thin layers. Stratovolcanoes, also known as composite volcanoes, are highly explosive and contain multiple vents, leading to massive eruptions that cause molten rock to stack up in steep, sloped layers. Scoria volcanoes, or cinder cones, are usually symmetrical and have a large crater at the summit formed by repeated eruptions from a single vent.Learn more about Volcanoes
A volcano is a special kind of mountain that contains an opening in the middle leading to a pool of molten rock, called magma, underneath the ground. When pressure increases to a certain amount, the volcano erupts. Many people know that a volcanic eruption causes hot lava to flow over the top of the volcano, but eruptions can also cause floods, mudslides, avalanches and falling ash. An active volcano's danger zone extends about 20 miles in all directions.Full Answer >
A magma chamber is a structure made up of solidified crystal mush and molten rock located below the surface of the Earth. When a magma chamber solidifies and cools, it is known as a pluton.Full Answer >
Volcanoes occur when molten rock from underneath the Earth's crust rises up. This molten rock comes from the mantle, not from the Earth's core. Because of plate tectonics, volcanoes can form relatively quickly.Full Answer >
A volcano erupts when the pressure of a subterranean pool of magma becomes great enough to crack the earth's crust. Whether the eruption results in a violent explosion or a slow seepage depends on several different factors, according to How Stuff Works.Full Answer >