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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 lave 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. Volcanoes were important contributors to the early earth atmosphere by relasing gasessuch as nitrogen (N2), cardon dioxide (CO2), and ammonia (NH4).

Volumes of Some Well-Known Volcanic Eruptions 

       Eruption                      Date           Volume in km^3
       --------                      ----           --------------
       Paricutin, Mexico             1943                 1.3
       Mt. Vesuvius, Italy          79 A.D.                3
       Mount St. Helen, Washington   1980                  4
       Krakatoa, Indonesia           1883                 18
       Long Valley, California     pre-historic        >450 & <700
       Yellowstone, Wyoming        pre-historic           2400
Note that volcanic eruptions that occured before historic times were several orders of magnitude larger (more than 1000 km3 in erupted volume) than ones observed by humans.
Volcano Web Introduction

created by Rich Castellano [email protected]
Volcanic Studies, Big University

last modified: April 1, 1995

URL: http://www.big.edu/web/xxxxxxxx.html

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