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BARREN ISLAND


Published on: 12/13/2020 11:17:57 AM

If one could slice the earth from one end to the other, the earth's interior would be seen to comprise an outer solid crust (0-35) km), a highly viscous mantle (35-2890 km), a liquid outer core (2890-5150 km) that is much less viscous than the mantle, and a solid inner core (5150-6360 km). The mantle has molten magma which finds its way through cracks or weak structural openings to rise to the surface of the earth in the form of hot lava, gases and/or ash in the form of volcanic eruption, as the pressure inside builds up to a critical limit.

 

A volcanic eruption may be silent and compose of only gases if the magma is thin. On the other hand, if the magma is thick and sticky, the gas cannot escape, so it explodes with a loud thundering noise and explosion. The magma pours out from fissures or cone like features flowing down the sides. Volcanic eruptions are known to have changed the weather, bring devastation to the area and wiping out life–human, animal and plant–from the area.

The Mount St Helens' eruption in 1980 killed thousands of animals and birds while the eruption of Tambora, Indonesia, in 1815, killed around 92,000 people and threw ash and gas into the atmosphere that cooled the world climate for more than a year. The evidences of Tambora eruption are available in most of the ice cores drilled across the world as volcanic ash.

The world has several hundreds of active volcanoes where lava is intermittently thrown out. In India, the Barren Island, located in the union territory of Andaman and Nicobar is the only active volcano. Some volcanic activity in the past has been reported from the nearby island of Narcondum. Geologically, the site of volcano lies in the midst of a volcanic belt on the edge of the Indian and Burmese tectonic plates.

The volcano attains a height of 354 m with a 2 km wide caldera. Since 1787, when the first eruption is recorded, the volcano is known to have erupted more than six times notably in 1789, 1795, 1803, 1852, 1991 (lasting 6 months), 1994 and 2005. The most recent eruption took place in 2017.

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