Essays

Hot! Fire! Destruction! These are words that most people associate with volcanoes. But some good effects can come out of volcanoes. Volcanoes also have their own special mythology associated with them. A lot of volcanoes have some general characteristics in common. There are many volcanoes around the world and some have special characteristics. So come along and take a trip into I he wonderful and exciting world of volcanoes.

Over 550 volcanoes have erupted on the surface of the Earth since human kind has been able to record history. Their destructiveness has claimed the lives of over 200,000 people during the last 500 years with 28,000 deaths between 1990 and 2000 alone. They have also caused an immense amount of property damage.

The biggest eruption of the twentieth century was the eruption of Novarupta on the peninsula of Alaska. The amount of lava that erupted measured roughly 15 cubic kilometres! The lava erupted equalled 30 times the amount of the amount of lava Hi at came from Mount Saint Helens and it is also the equivalent of 230 years of eruptions at Mount Kilauea. The eruption lasted for 60 hours on June 6, 1920.

The biggest eruption, despite its size, was not the most destructive, for the most destructive was the eruption of Mount Saint Helens in Oregon during the week of

May 18th, 1980. The Novarupta eruption mainly caused just loss of property. Although some people did die, this volcano was kind of weak compared to the size of the eruption and amount of lives lost in  other eruptions like Tambora, Indonesia in 1815  where 92,000 people died.

Despite all of these bad effects, some life still shines through these tragedies. For example the ash that a volcano spews out covers many square miles of plants and trees. This holds in water and waters plants. The ash also contains many nutrients that plants use.

A little more than 80 per cent of the Earth's surface is volcanic in origin, meaning that most of the Earth's surface was formed by volcanoes. Also, magma deposits heat water underground, which produces geothermal energy.

The word volcano comes from an island off the coast of Sicily called 'Vulcano'. The people of Sicily thought that the clouds of dust and spurts of lava were made by Vulcan, the blacksmith for the Roman gods. They believed that Vulcan forged thunderbolts for Zeus and weapons for Mars on that island.

Out of the 550 of the world's active volcanoes, the world's largest active volcano is Mauna Loa, on one of the Hawaiian Islands. The island protrudes around 13,677 feet above sea level, while the whole island was formed by an underwater volcano. This brings it 28,000 feet above the ocean floor where it started.

From the base underwater to the summit above water, this volcano stands higher than Mount Everest. There are two main types of volcanoes in the world today, the first is felsic and the second is mafic. Felsic volcanoes have high silica content and a light colour to the lava.

The second, mafic, has just the opposite, a low silica content and a darker colour. Then there are underwater volcanoes and above ground volcanoes. The underwater volcanoes are less known about than above ground for the obvious reason that they are seen when they are above ground.

Underwater volcanoes produce some things called black smokers. They are basically merely ash as well as black smoke that combine and heat up water to boiling temperatures.

An interesting fact about underwater volcanoes is that some islands have been formed by lava eruptions building up year after year. An island chain that is very well known that has been formed by this process is the chain of the Hawaiian Island chain. This chain also includes the world's largest volcano, Mauna Lao, which, when you count the height underwater and the height above water is taller than Mount Everest.

Some volcanoes have been found in our solar system, which are not on the planet Earth. One volcano, which is the largest one in our solar system. Is Mount Olympus Mons on the planet Mars. This is the only volcano found on the planet Mars. There are also numerous volcanoes found on lo, a moon of the planet Jupiter. These volcanoes also show some plate tectonics on lo, even though no plate tectonics la believed to have occurred on Mars.

Volcanoes form when magma, melted rock ; underground (it is called lava when it reaches the  surface) (most of it forms around 50 to 100 miles underground), mixes with gas and rises, pressure builds against the surface, the magma breaks through and you get a volcano.

Shield volcanoes form when a lot of lava spills out of a vent and goes in a broad, flatter area. Another type of different volcano is a cinder cone. Cinder cones are made when tephra, thick globs of magma, erupts from a vent in the ground and comes back down then accumulates.

A famous one is Paricutin in western Mexico. It started to form in 1943 in the middle of a farmer's cornfield, and then it started to stop in 1952. When it was finished, the cinder cone was 1,345 feet higher than the base. Then there are composite volcanoes, which form when tephra and lava erupt from the same vent. One example of this is Pompeii and Japan's Mount Fuji.

When all of the magma is drained out of the chambers of the volcanoes, called magma chambers, sometimes the volcano can't support itself and collapses. This leaves a crater called a caldera. So, you have learned about some specific volcanoes as well as the properties that go along with them (even if they are bad). So it can be said that you found out that volcanoes aren't all that bad.