How Do Volcanoes Erupt?

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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.

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.