Q:

What causes a volcano to form?

A:

Quick Answer

A volcano forms when magma pushes up through the Earth's crust from below, depositing lava on the surface. This lava cools, creating volcanic rock. Over time, repeated eruptions of lava build a cone-shaped mountainous structure, producing a volcano.

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Full Answer

Volcanoes typically form around three tectonic features. Plate boundaries are common spots for volcano formation, either divergent plate boundaries where two plates are separating or convergent boundaries where two plates collide. The resulting damage can produce weak spots in the plate, allowing magma to flow up from beneath. Divergent boundaries tend to produce shallow flows of lava and occur regularly on the ocean floor. Convergent boundaries produce thick, viscous lava that may not reach the surface and is responsible for many of the undersea mountain ranges on the planet.

Hot spots are areas where a tectonic plate is weakened, allowing an upwelling of magma from below. Since tectonic plates move over time, these hot spots can create a series of volcanoes, each going dormant when it moves away from the hot spot. The Hawaiian islands are believed to be a result of a moving hot spot underneath the Pacific that created a chain of islands and undersea mountains from Midway to the currently active volcano of Kilauea.

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Related Questions

  • Q:

    How does a volcanic neck form?

    A:

    A volcanic neck forms when lava inside a caldera cools after magma stops feeding the mountain, and then the outside of the extinct volcano erodes after millions of years. The cooled lava remains intact because it is harder than the surrounding rock that eroded. Perhaps the most famous volcanic neck in the United States is Devil's Tower in Wyoming.

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  • Q:

    How is a volcano formed?

    A:

    A volcano forms when magma rises through weakened areas of the crust from a magma reservoir many miles deep within the earth, pushing itself up through a vent. This vent acts as a release valve for pressure building up below, and when the new volcano erupts, thousands or millions of pounds of ash and molten rock slowly accumulate, forming a volcanic mountain.

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  • Q:

    What do you call hot lava cooling?

    A:

    When magma rises up to the surface of the Earth from a volcanic eruption or through vents, it turns into lava. When this lava stops flowing and cools, it hardens into what is known as igneous rock.

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  • Q:

    How is a volcano made?

    A:

    A volcano is any place where magma from the Earth's interior breaks through its surface, as explained by How Stuff Works. Magma is molten rock that is partially liquid, partially solid and partially gaseous. Interaction between the plates that form the Earth's crust is one of the primary catalysts for creating magma.

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