Volcanoes: Volcano and Lava Acidic Lava

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  • Topic: Volcano, Lava, Magma
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  • Published : January 28, 2012
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A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot magma, volcanic ash and gases to escape from below the surface. The lifespan of a volcano can be about from a few months to a million years. A very popular way of classifying the volcanoes based on the frequency of their eruptions. Magma is molten rock within the earth’s crust. When magma erupts through the earth’s surface it is called lava. Lava can be thick and slow-moving or thin and fast-moving. Rocks also come from volcanoes in other forms, including ash (finely powdered rock that looks like dark smoke coming from the volcanoes), cinders (bits of fragmented lava), and pumice (light-weight rock that is full of air bubbles and is formed in explosive volcanic eruptions - this type of rock can float on water). The largest volcano on the earth is Mauna Loa located in Hawaii. This volcano is about 10,000m from the sea floor to the summit. It rises 4000m above sea level. The most active volcano is Mount St. Helens located in Washington state.

TYPES OF VOLCANOES
1. Active volcanoes
2. Dormant volcanoes
3. Extinct volcanoes
ACTIVE VOLCANOES
Volcanoes which erupt frequently are called active volcanoes. Active volcanoes are those which erupted lava, gases, pumice, cinder etc in the recent historic periods. Presently there are about 500 active volcanoes around the earth of which most of them are located in the pacific ring of fire. E: g Mauna Loa which erupted recently in Hawaii in the year 1984. Augustine volcano which is located in Alaska and erupted in the year 1991. Mount St. Helens in Washington which erupted from 1980-1986 and again in the year 2004.

PACIFIC RING OF FIRE WHERE MAJORITY OF THE EARTH’S VOLCANOES ARE LOCATED.

DORMANT VOLCANOES
It is normally difficult to distinguish dormant and extinct volcanoes from each other. Dormant volcanoes are those which erupted in the past and are likely to erupt again after remaining inactive for fairly long...
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