What is a Volcano? The scientific definition of a volcano is a geological landform, consisting of a fissure in the earth s crust, above which a cone of volcanic material has accumulated. The cone is formed by the deposition of molten or solid matter that flows or is ejected through the vent from the interior of the earth. At the top of the cone is a bowl shaped vent called a crater (Decker). There are many types of volcanoes, but scientist and geological experts have divided them into three groups. 1) Shield Volcanoes 2) Cinder Volcanoes 3) Composite Volcanoes. Shield volcanoes are formed when a large amount of free lava spills from a vent and spreads widely; lava gradually builds forming a low, broad dome shaped mountain. Cinder volcanoes are formed from the build up of accumulated tephra forming a cone shaped mountain. Composite Volcanoes are formed when both lava and tephra erupt from a central vent. The materials pile up in a towering cone shaped mountain (Cashman).

Why do Volcanoes erupt? Eruption of a volcano is beneficial to the volcano s growth. The process starts when molten rock and other chunks of heated materials start their way up to the surface due to the increases of natural gases. The magma collects in chambers surrounded by gases and

extremely high pressure building up from inside. Eventually, all the build up of magma and other material is push or ejected, breaking through the earth s surface. Eruptions after eruptions, eventually builds up the mountain cone of the volcano from debris and lava flow. Different volcanoes have different eruptions. Some eruptions are huge fiery clouds that rise high over the mountains, and glowing rivers of lava flow down its sides. In other eruptions, red-hot ash and cinder shoot out the mountaintop and large chunks of hot rock are blasted into the air. Eruptions are not only limited from top, but also occur on the ocean floor. The lava flows from small cracks from the volcano s internal foundation, gradually building up the ocean floor, forming natural communities for the surrounding sea life. Active eruptions of volcanoes, not only produce destructive lava flows, but also pyroclastic clouds which are like avalanches of extreme heated clouds that roll down the sides of the volcano destroying whatever in its path. Also, mudslides, and landslides are induce through volcanic eruptions. Eruptions that occur beneath the ocean floor create Tsunamis, which spreads in all directions. The majority of lives lost from volcanic eruptions, are primarily from these other aspects of the eruptions (Wood).

During the cooling stage , a volcano continues to emit acid gases and vapors. During this phase, hot springs may arise from the volcano s bottom foundation. Example of this occurrence can be found at Yellow Stone National Park. After becoming totally inactive, a volcano undergoes progressive reduction in size through erosion caused by running water, glaciers, wind or waves. Thus, leaving only a volcanic pipe, a vent filled with lava or fragmental material.

Although volcanoes have the reputation of being very dangerous, there are advantages of living near a volcano. Volcanoes provide resources for energy extraction, also called geothermal resources. Heat from the earth's crust is being converted to energy. The big advantages to this type of energy are that it is very clean and the resources are nearly inexhaustible. When a volcano erupts it throws out a lot of ash. At short notice this ash can be very harmful to the environment, but on the long term the ash layer, which contains many useful minerals, will be converted to a very fertile soil. Nearly everywhere volcanoes are located, people use the rich soil for farming. Even after an eruption people still return because of the fertile soil around the volcano. A big economical advantage of volcanoes is that they generate tourism. A country such as Hawaii and the surrounding islands are getting a lot income from tourism due to the number of volcanoes situated around the area.

In summing up, Volcanoes are very powerful and unpredictable. Even with advanced technological instruments scientists have tried to study volcanoes to avoid future disasters, but the unpredictability of volcanic eruptions is making the study very difficult. Volcanoes in general, are one of nature s many astonishments, they were here since the dawn of the earth s evolution, creating and destroying the environment around them; acting like nature s own recycling tool. In my opinion, I see volcanos not as a destructive element but as an energy source that mankind can use to help them selves in the near future.

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