Volcano Types
The
distructive power of a valcano is one of the most violent and deadly of
all
natural forces. In a short period of time, these massive explosions of
the
earth’s crust can shatter whole communities. Valcanoes are very
distructive no
matter how big or how small they erupt at. They cause the
highest amount of
deaths and the greatest amount of damage. Of the two major
types of Volcanoes,
andestic and basaltic, the two typical volcanoes begin
life when a mass of
low-density magma forces its way to the surface. When the
density of the rising
magma is the same as that of the surrounding rock, it
gathers in a magma
chamber. Any rise in pressure in the chamber may now push
the magma upwards
through cracks in the overlying rock. As the magma
traveling up a crack
approaches the surface, the pressure from the overlying
rocks reduces; gases are
released from the magma and expand so suddenly that
an explosion rips open a
funnel shaped vent (called a diatreme) to the
surface. The lava that blasts out
of the vent then cools, to form cinders,
ash and dust - all referred to as
"Tephra". A ring of tephra collects around
the vent and, as the
eruption subsides, this blocks up the diatreme.
Volcanoes have erupted in many
different places. Volcanoes have erupted in
The Philippines, Java, Papua New
Guinea & Hawaii and many other places.
"The Ring of Fire", located
around the Pacific Ocean, is 20 or so places with
active volcanoes in them
joined by one big imaginary line that forms a circle
(or "Ring") when
scaled down to the size on a map. Somewhere in the world an
eruption occurs at
least once a month. Whether it be big or small it doesn’t
really matter at
all. If it kills 1 person or 1 000 people it is still
counted as an eruption. In
some countries volcanoes are common and erupt
frequently as in Hawaii. But in
other countries like Australia there are no
eruptions at all. That could be
because all the volcanoes are dormant or
there are simply no volcanoes at all.
In 1815, the most devastating eruption
ever recorded, killed approximately 92
000 people. 10 000 people died
directly from the volcano and a further 82 000
died from famine. The volcano
is located at Tambora, Sumbawa in Indonesia.
Recently a volcano erupted in
Monserrat, West Indies. It devastated farms,
houses and streets became rivers
of lava.