EARTH: VOLCANIC ERUPTION

The volcanic eruptions:

    When a volcano sprays its summit, the power of this explosion comes from carbon dioxide. The enormous underground pressures trap the gas in the dissolved form magma. When the chimney suddenly opens, the pressure decreases sharply and the gas forms bubbles that increase in volume, just like what happens when you open a soft drink after shaking it. These bubbles bring the magma up along the chimney which then releases a shower of lava, ashes and even pieces of burning rock. Today, scientists can more accurately predict eruptions, but not predict their type.
If this magma spreads to the surface in the form of simple lava flows, the eruption is called effusive. If it is emitted discontinuously in liquid, solid and gaseous form, the eruption is called explosive.
    In fact, the same volcano may experience one or the other type of explosion or both during the same eruption.

An extraordinary show!

    Mount Stromboli, a volcano on an island near Sicily in Italy, is very active. Hot lava surges up its 926 m crater, producing frequent small explosions.
    People come to watch the projection of these yellow and hot bombs (called pyroclastic bombs).
    The last eruption of this volcano occurred in February 2007.

Mount Saint Helens:

    On 18/05/1980, it was a Sunday morning, when Mount Saint Helens in Washington, D.C., U.S.A., erupted for the first time in 123 years.
    The increased pressure within the volcano has inflated its flank, causing a landslide of billion tons of rock. The explosion produced a mushroom cloud, consisting of gas and ash, 19 km high.

The pyroclastic power:

    May after the first explosion of Mount Saint Helens, a blazing cloud rolled down its northern flank at a speed of 160 km/h, reducing trees and vegetation to ashes. The explosion was so intense that it charred the flora for miles, creating an unusual landscape of desolation.

A red sky in the night!

    The ashes of volcanoes can be carried by winds at great distances. When they veil the rays of the Sun, they produce bright red sunsets. But at the same time, they cool Earth’s temperature.
Take Mount Pinatubo in the Philippines: in 1991, the ashes of its eruption cooled the Earth’s surface.

Frozen for eternity:

    In 79 BC, the inhabitants of Pompeii, Italy, watched the eruption of Mount Vesuvius when a cloud of incandescent ashes and gas, called a fiery cloud, rolled down the mountain. All died suffocated before being buried in the ashes. Thanks to plaster molds, we were able to reconstruct the prints of their frozen bodies.