Volcanic Distributions

Most of the world's volcanoes are found along the plate edges. The largest volume of volcanic material is formed at seafloor spreading centers where the basaltic material erupts quietly onto the ocean floor. These volcanoes are known as rift volcanoes. Such volcanoes can be found along the Mid-Atlantic Ridge and the Great Rift Valley System in East Africa.

Volcanoes formed over subduction zones where plates converge erupt violently. They are known as subduction volcanoes and have silica-rich lava. These volcanoes may be formed in fold mountain ranges or as offshore islands. There is a belt of subduction volcanoes in the Mediterranean region. Some examples are Mount Etna and Mount Stromboli.

About two-thirds of the world's volcanoes are located at the Circum-Pacific region. This belt is called the Pacific Ring of Fire. It stretches from New Zealand, the southwest Pacific, Indonesia, the Philippines, Japan and Kuril Islands to Kamchatka. It continues into the Aleutian Islands and Alaska in North America and runs down to the Cascade Range on the west coast of North America to Central America and to the Andes Mountains on the west coast of South America.

A few volcanoes are found away from the plate boundaries. These are hot spot volcanoes that are formed as a result of plate movement over a hot spot in the mantle. Some examples are the Hawaiian volcanoes in the Pacific Ocean such as Mauna Loa.

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