Sunday, November 18, 2007

VOLCANO





WHY DO VOLCANOES ERUPT
At about two miles below the surface of the earth the temperature is high enough to boil water. If it were possible to dig down 30 miles, the temperature would be about 2,200 degrees fahrenheit. This is hot enough even to melt rocks. At the centre of the earth scientists believe that the temperature could be as high as 10,000 degrees fahrenheit.

When rock melts, it expands and needs more space. When the pressure is greater than the roof of rock above it, it bursts out causing an eruption. When the pressure is greater then the roof of the rock above it, it bursts out causing an eruption. When the volcano erupts it throws out hot, gaseous liquid called lava or solid particles that look like cinders and ash. The material piles up around the opening and a cone-shaped mound is formed.





WHY ARE VOLCANIC BOMBS DANGEROUS?

A major volcanic eruption can send boulders flying high into the air. These boulders, called volcanic bomb, can be very large. Most of the material thrown of the erupting volcano is ash, which forms a huge cloud. Steam released and these can be extremely dangerous to bystanders.

On August 24, in the year AD 79, Mount Vesuvius, a volcano in Italy, violently erupted. The lava, stones, and ashes thrown up by the volcano completely buried two nearby towns.

No comments: