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 with me into
the 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 26,000 deaths between
1980 and 1990 alone. They have also cause an innumerable
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 to roughly 15 cubic
kilometers! All of the lava erupted equaled to the amount
of 30 times the amount of lava that 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. This eruption mainly caused just loss of property,
because many people didnt expect the volcano to erupt.
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 percent of the Earths surface is volcanic in origin,
meaning that most of the Earths surface was formed by
volcanoes. Also, magma deposits heat water underground
which produces geothermal energy.
The word volcano comes from an island off of the coast
of Sicily called Vulcano. The people of Sicily thought that
the clouds of dust and spurts of lava were made from Vulcan,
the blacksmith for the Roman Gods. They believed that
Vulcan forged thunderbolts for Zeus and weapons for Mars on
Out of the 550 of the worlds active volcanoes, the
worlds largest active volcano is Mauna Loa, it is 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
There are two main types of volcanoes out there in the
world today, the first is felsic, and the second is mafic.
Felsic volcanoes have a high silica content and a light
color to the lava. The second, mafic, has just the
opposite, a low silica content and a darker color.
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 just
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 worlds largest volcano, Mauna Lao, which, when
you count the amount underwater and the amount above water
is taller than Mount Everest.
Some volcanoes have been found in our solar system that
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 Io,
a moon of the planet Jupiter. These volcanoes also show
that some plate tectonics on Io, even though no plate
tectonics is 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), when the magma
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 Paricutn in western Mexico. It started to form in 1943
in the middle of a farmers corn field, 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 Japans Mount
When all of the magma is drained out of the chambers of
the volcanoes, called magma chambers, sometimes the volcano
cant support itself and collapses, this leaves a crater
called a caldera.
So, I hope that you have learned about some specific
volcanoes as well as the properties that go along with them
(even if they are bad). I also hope that you found out that
volcanoes arent all that bad.
World Book Encyclopedia, Book U-V, pg.462-pg.467