Volcanic Eruption

One of the most dangerous natural disasters in the world is the eruption of volcanoes. This is a natural process of removing the materials from below and expelling it out of the earth's interior. The hazards are brought by different volcanic materials which include lava flowing out of the crater, fragmental products that are thrown into the air, and gases escaping from the magma near the surface. Earthquakes and tsunamis add even more to the danger caused by an eruption. In the 20th century, about 74,000 people are listed to be dead due to mudflows/ lahars and tsunamis. The list is extended even more by 3,000 which are associated to the disease and starvation caused by the volcanic events ("Volcanoes").

Volcanic eruption arises due to the escape of magma from the interior of the earth. Magma is formed when there is a decrease in pressure in the upper mantle. This area is usually at the subduction zones wherein tectonic plates move onto one another. The pressure lowering and movement of tectonic plates causes the melting of rocks leading to the formation of magma. This material is composed mainly of 25 % molten rocks and 50 % solid rocks and gases. Another interesting property of magma is its lower density compare to solid rocks which can be the reason of its upward movement ("What Causes a Volcano to Erupt?").

Three theories can explain the eruption of volcanoes. The first theory attributes the eruption to the buoyancy and pressure of the gas component of the magma. When the gas is exposed to extreme pressure, it tends to escape from pressurized area. Since it is highly dissolved in the magma at high pressure, it takes the other components in its movement. In the second theory, the percent composition of the dissolved gases plays the key in the eruption of volcano. As the magma approaches the surface of the earth, the solubility of water in the magma tends to decrease. This leads to the separation of water from the magma. The removal of one component will always result to the increase in the percent composition of the other components, the dissolved gases in this case. Once the percent composition of dissolved gases increases, the magma disintegrates into pyroclasts giving an explosive eruption. Lastly, the third theory emphasizes that the upward movement of magma is due primarily on the introduction of newly formed magma in the magma chamber. The newly formed magma replaces the old ones in the chamber by pushing the latter upward until it is out of the earth's crust opening ("Volcanic Eruptions: What Causes Volcanoes to Erupt.").

The most recent volcanic eruption was traced to be at Marapi volcano located in Western Sumatra, Indonesia. It was reported that the eruption happens last September 26 of this year between 16:30 to 18:15 h of the local time. The eruption was considered modest with an ash column rising 1.5 to 2 km from the volcano's crater. Loud roaring noises were