Q:

How do volcanoes erupt?

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Quick Answer

Volcanic eruptions can either be effusive or explosive. An effusive volcanic eruption occurs when the lava pours out onto the ground from the volcano's vent. When the molten rock or magma is thin and runny, gases can easily escape and the lava flows freely and travels far. An explosive volcanic eruption is caused by thick and sticky magma, which prevents gases from escaping and causes them to explode violently.

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How do volcanoes erupt?
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A volcanic eruption occurs when magma collects in the magma chamber and rises to the surface due to the pressure from the solid rocks around it. As the magma rises, bubbles form from the dissolved gases in the magma and exert pressure, causing the magma to rise to the surface. In an explosive eruption, magma breaks up in the air into fragments called tephra, which can take the form of ash particles, small hot rocks or large boulders. Unlike an effusive eruption where lava travels slowly, an explosive eruption can be dangerous and deadly. Massive volcanic eruptions also leave behind thousands of tons of volcanic ashes that can suffocate humans, animals and plants. Most magma erupts through the central vent or the opening surrounded by the crater. Some volcanic materials, however, escape through smaller channels formed on the sides of the volcano.

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Related Questions

  • Q:

    Why do volcanoes erupt?

    A:

    Hot melted rocks collect under the Earth's surface and when the pressure becomes too hard, the Earth's skin breaks, and a volcano erupts. The melted rock inside the Earth is called magma, but when it comes out in an eruption, it is called lava.

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  • Q:

    How do cinder-cone volcanoes erupt?

    A:

    Cinder-cone volcanoes, properly called scoria volcanoes, erupt when expanding gas bubbles drive lava to the volcano's surface. Because of this pressure, the lava fountains are usually very high and vertical. By the time the erupted material lands, it is already cool.

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  • Q:

    How do shield volcanoes erupt?

    A:

    Shield volcanoes usually erupt with splattering liquid lava that fountains out and has little explosive potential. This forms some of the largest volcanoes on Earth with very gentle slopes, since the liquid water cannot build steeper slopes. This type of lava cools to form basalt rock.

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  • Q:

    What causes volcanoes to erupt?

    A:

    A volcanic eruption is caused by the injection of magma into a full magma chamber, the buoyancy of magma and the pressure exerted by the gases in the magma. The volcano simply acts as an opening through which magma and dissolved gases are discharged.

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