Famous Volcanoes

Although major eruptions rarely happen, Volcanoes are a significant part of people’s lives because thousands are killed by volcanoes every year and volcanoes help scientists understand how the earth works.  Volcanoes are very significant in both recent and ancient history, due to their explosions destroying cities and land.

            Many people ask, though, how are volcanoes formed?  The earth is divided into five different layers under the surface.  The crust is what we live on, and goes about 40 miles into the earth.  It is made mostly of basalt and granite. The crust is actually broken into many huge plates that float on the upper mantle.  The upper mantle is right under the crust, and contains mostly magma, which is hot, liquid rock.  These plates tend to bump into each other.  When they do, one plate is usually forced under another and into the upper mantle.  Once the tectonic plate is forced under, the magma from the upper mantle is forced upwards and onto the surface, creating a volcano. 

At first, this volcano is very small, usually sloping upwards very shallowly.  But, when the volcano erupts, all the magma turns into rocks, making the volcano bigger, as seen in the picture.  The black line represents the ground before the volcano.  The red line represents the ground after one eruption, the green for the second eruption, and third eruption for the purple, and blue for the fourth eruption.  The lava builds upon the old magma making the mountain higher.

            But, why is it important to know more about volcanoes?  Volcanoes are important because they tell scientists how the earth works. The theory of tectonic plates and the inside of the earth helps us understand and predict natural disasters such as volcanoes and earthquakes.  Scientists could not have done this without the help of volcanoes because it would be almost impossible for scientists to dig down thousands of miles today.

            Another reason learning about volcanoes is important is because volcanoes create islands such as Hawaii.    Hawaii is very important to the United States because it is a major source of income due to its tourist business.  Hawaii changed the course of history during the attack on Pearl Harbor, engaging the US to go to war with the Axis.  If the US hadn’t joined the war, the entire course of history would be changed, just because of an island a volcano created.