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Introduction

A volcano is a location where magma, or hot melted rock from within a planet, reaches the surface. It may happen violently, in a massive supersonic explosion, or more quietly, as a sticky, slow lava flow.

Volcanoes have been a part of earth's history long before humans. Compare the history of human beings, a few million years in the making, to that of the Earth, over four billion years in the making.

Volumes of some well-know volcanic eruptions

		  Eruption                      Date           Volume in km^3
		  --------                      ----           --------------
		  Paricutin, M�xico             1943                 1.3
		  Mt. Vesuvius, Italy          79 A.C.                3
		  Mount St. Helen, Washington   1980                  4
		  Krakatoa, Indonesia           1883                 18
		  Long Valley, California     pre-historic        500 - 600
		  Yellowstone, Wyoming        pre-historic           2400
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