Why are there volcanoes?

The Canary Islands are a group of seven major volcanic islands that extend for almost 300 miles (500 km) east to west about 60 miles (100 km) off the coast of northwest Africa.

Volcanoes are a natural way that the Earth and other planets have of cooling off. Planets are warm in their mantles. Heat inside planets escapes towards their surfaces. Heat sometimes melts rocks, which then rise buoyantly toward the planet's surface. When the hot rocks - called magma - and included gases break through the crust, an eruption occurs. The buildup of ash and lava flows around the eruption hole (or vent) makes a volcano. Some volcanoes erupt for only a short time - a few days to weeks and never erupt again. Large volcanoes such as stratovolcanoes and shields erupt many thousands of times throughout their lifetimes of hundreds of thousands to a few million years.

Chuck Wood


The Earth has volcanoes because it is hot inside. In some places it is hot enough to turn solid rock into liquid rock. Geologists call the liquid rock magma. The magma rises towards the surface because it is less dense than the surrounding rock (like a hot air balloon rising through the cooler air). If the magma reaches the surface it is called lava and lava accumulates to make a volcano.

Steve Mattox


The Earth's interior is hot, and, as all hot things will do, the interior is trying to lose its heat and cool. It cools mostly by releasing its heat through volcanic eruptions. That is why there are volcanoes.

John Dvorak

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