A volcano is an opening, in the planet’s surface which allows hot, molten rock, ash and gases to escape from below the surface.
The name, “volcano” originates from the name Vulcan, a god of fire in Roman mythology. Volcanoes are like giant safety valves that release the pressure that builds up inside the Earth. The Hawaii islands were formed by 5 volcanoes.
Classified by the extent of their activity volcanoes are of four types. An ‘active’ volcano is one that erupts regularly. There are about 500 known active volcanoes on Earth, not counting those that lie beneath the sea.
A ‘dormant’ volcano is one that has not erupted for many years, although there is still some activity deep inside it. An ‘extinct’ volcano is one which has ceased to be active.
A volcanic eruption occurs when hot rocks and lava burst from a volcano; and geysers and springs are actually just volcanoes that throw boiling water high in the air. They are caused by volcanic heat warming trapped ground water.
The liquid rocks inside a volcano are called magma and when it flows out it is called as lava. Fresh lava has temperatures from 700 degrees C to 1200’C and glows red-hot to white hot as it flows.
Volcanoes are generally concentrated on the edge of continents, along the island chain, or beneath the sea forming long mountain ranges.
A major part of the world’s active volcanoes above sea level encircle the Pacific Ocean forming the “Ring of Fire.”
Volcanoes can have serious affects on the lands and people around them when they erupt. The destruction they leave in their wake accounts for the total annihilation of the surrounding landscape.
Buildings are destroyed, people are rendered homeless, people are killed, plant and animal life are both destroyed and the poisonous gases that emanate from the volcanoes can cause death and diseases like pneumonia in the people who survive it.
The volcanic ash that blows out of the volcano increases soil fertility by adding nutrients to the soil. Ground water heated by magma can be tapped for geothermal energy.
Most of the metallic minerals like copper, gold, silver, lead and zinc are mined from the magmas found deep within the roots of extinct volcanoes.