The Basics	In-Depth	Experiments	Witness Account
Words to Know	Experts Say	Be Ready!	Explore the Ring of Fire

In-Depth

Volcanoes are also located where plates are spreading apart. A ridge forms, and as the two plates separate, the mantle rock from below the surface flows up into the empty spaces between the plates. The mantle rock will melt, forming magma. As the magma flows out, it cools, hardening to form new crust. This fills in the gap created by the plates separating. Scientists have discovered this type of activity in the Atlantic Ocean along the Mid-Atlantic Ridge, where Iceland's volcanoes are found.

Some scientists believe that weather affects volcanic activity. Research seems to show that snow buildup at the North Pole might spur eruptions in other parts of the world.

What happens at hot spots?
Not every volcano in the world is near the plate boundaries. Some midplate, or intra-plate, volcanoes form over what geologist believe are stationary hot spots. Here, huge columns of magma rise from deep inside the earth and break through the plate. As the plates above the hot spot continue to shift, the magma will break through again to form new volcanoes. The Hawaiian Islands are the most famous midplate volcanoes.

A visit to the Big Island of Hawaii reveals more about volcanoes. Rather than fleeing from Kilauea, an active Hawaiian volcano that has been erupting continuously since 1983, tourists flock to the area hoping to glimpse the oozing lava. Volcanologists refer to Hawaii's volcanic eruptions as "quiet" eruptions. Gas escapes slowly rather than in one large violent explosion and visitors can usually safely view the lava flow. The ongoing flow has destroyed landmarks and beaches, but it has also created land — adding more than 560 acres of new land to the island.

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