http://www.soest.hawaii.edu/GG/HCV/kilauea.html
Por que los volcanes hacen erupcion?
That's because the Earth's outermost shell -- the
lithosphere -- is broken into a series of slabs known as lithospheric or
tectonic plates. These plates are rigid, but they float on the hotter, softer
layer in the Earth's mantle. There are 16 major plates. As the plates move
about, they spread apart, collide, or slide past each other. Volcanoes occur
most frequently at plate boundaries.
http://vulcan.wr.usgs.gov/Outreach/AboutVolcanoes/where_do_volcanoes_o
Que pasa cuando un volcan hace erupcion?
When a volcano erupts, magma bursts out. Dust, gas, steam and
hot rock shoot into the sky. Streams of magma called lava come to the surface
and pour from the top of the volcano and down its sides. Sometimes the eruption
is so loud it sounds like an explosion from a large bomb. Hot magma cools as it
rises to the top. Some of it becomes solid on the way up. The solid pieces are
blasted out in the eruption. The smaller pieces about the size of marbles are
known as volcanic ash and the larger ones are called volcanic bombs. Volcanic
bombs can be as big as and as heavy as trucks. The very small particles are
called volcanic dust.
http://members.aol.com/ckckside/reports/volcanoes/vol3.htm
Evacuation
Timely evacuation from volcanic eruptions can eliminate the hazard to human
life, even though destruction of buildings may still have to be accepted as
inevitable. The real danger is from the more violent types of volcano in the
less well-developed parts of the world where monitoring cannot be comprehensive.
In this situation danger zoning is probably the only available defense--and even
this is lamentably inadequate in many parts of the world. Programs of hazard
zoning on many volcanoes in populated areas could be a worthwhile planning aid
to be carried out well before the first rumblings of an impending eruption.
http://dmc.engr.wisc.edu/courses/hazards/BB02-04.html
Destruction
Destroys timber,
crops,
houses,
bridges.
RECORD
The greatest volcanic disaster in recent geologic history, in the region,
occurred in the Quaternary period of Ice Age, approximately 75,000 years ago.
This volcanic explosion devastated the center of the island of Sumatra. The
volume of tephra discharge from this eruption is estimated at 2,000 cubic km, a
tremendous quantity considering that the Krakatau catastrophic eruption of 1883,
only resulted in 15-20 cubic km of ejected tephra. The collapse crater, the
caldera, formed by this giant eruption which must have lasted for several months
or even years, is filled presently with the waters of lake Toba, on that island.
The caldera is 100 km long.
http://www.drgeorgepc.com/NaturalDisasters.html