Q:

How does a volcano form?

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Quick Answer

A volcano forms when a vent in the Earth's crust allows magma to well up from below. The magma fills a void underneath the surface, and when it builds up enough pressure, it bursts through to the surface. As the magma cools, it hardens into rock, and multiple eruptions may build up the mountainous form of a volcano.

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How does a volcano form?
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The Earth's crust seems solid, but it is actually made up of 17 large, rigid plates floating over a hot, malleable sea of molten rock. When these plates collide or pull apart, they can allow this molten material, called magma, to make its way upward into the crust. If magma finds a particularly weak spot, it may burst through to the surface, creating a volcano. These can come about as the result of a slow accretion of cooling lava, or they can be the result of spectacular, pressurized explosions.

In some cases, a single vent may create multiple volcanoes. The Hawaiian Islands are the result of a tectonic plate passing over a particular hot spot in the mantle, and that hot spot has created several volcanic mountains in the sea floor. The chain of islands and mountains created by this vent extends as far as Midway, and Kilauea is the current site of the active volcano.

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Related Questions

  • Q:

    How does a volcano occur?

    A:

    Volcanoes occur when magma and heated gases from below the Earth's crust are channeled to the surface through fissures in the crust layer. Magma is molten rock that is called lava once it reaches the surface.

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  • Q:

    Where do volcanoes form?

    A:

    Volcanoes can form anywhere the Earth's crust allows magma to reach the surface. Typically, this occurs around plate boundaries, either where plates are pulling apart or where one is forcing its way under another. Weak spots can also develop away from plate edges, creating magma vents called hot spots.

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  • Q:

    What is a side vent in a volcano?

    A:

    Side vents, also known as secondary vents, in a volcano allow some of the magma and gases to escape but are not the main vent where the eruption takes place. One of the volcano's most recognized characteristic is the crater, but this hole actually forms after the eruption has taken place.

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  • Q:

    What is a main vent in a volcano?

    A:

    The main vent of a volcano is the outlet chamber in the Earth's crust that allows hot magma to reach the surface. While secondary vents may form to alleviate the pressure caused by a magma chamber, the main vent is responsible for giving volcanoes their familiar cone shape.

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