History's Most Destructive Volcanoes

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The eruption
of a volcano on the island nation of Iceland on Saturday is a result
of the tectonic processes that have continuously shaped and re-shaped
the Earth’s surface for billions of years. These processes are responsible
for some of the biggest, deadliest eruptions in history.

The Eyjafjallajokull
(AYA-feeyapla-yurkul) volcano – part of the volcanic complex
that originally
formed Iceland
– erupted on March 20 for the first time
in nearly 200 years. While the eruption has not been a major one
so far, it did cause residents in the surrounding areas to evacuate,
as they wait to see if the volcano will continue to spew lava and
ash or quiet back down.

Other residents
of volcanically active areas, whether prehistoric creatures or modern
humans, haven’t always had enough warning to escape before a nearby
volcano blew its top, sometimes virtually destroying everything
for many miles around.

Here are some
of the biggest, most destructive volcanic eruptions on Earth:

Deccan Traps
– Deccan Plateau, India – about 60 million years ago

The Deccan
Traps are a set of lava beds in the Deccan Plateau region of what
is now India that cover an area of about 580,000 square miles (1.5
million square kilometers), or more than twice the area of Texas.
The lava beds were laid down in a series of colossal volcanic eruptions
that occurred between 63 million and 67 million years ago.

The timing
of the eruptions roughly coincides with the disappearance of the
dinosaurs, the so-called K-T mass extinction (the shorthand given
to the Cretaceous-Tertiary extinction). Evidence for the volcanic
extinction of the dinosaurs
has mounted in recent years, though
many scientists still support the idea that an asteroid impact did
the dinosaurs in.

Supervolcano – northwest corner of Wyoming, United States –
about 640,000 years ago

The history
of what is now Yellowstone National Park is marked by many enormous
eruptions, the most recent of which occurred about 640,000 years
ago, according to the United States Geological Survey. When this
gigantic supervolcano
, it sent about 250 cubic miles (1,000 cubic kilometers)
of material into the air. The eruptions have left behind hardened
lava fields and calderas, depressions that form in the ground when
material below it is erupted to the surface.

The magma chambers
thought to underlie the Yellowstone
also provide the park with one of its enduring symbols,
its geysers, as the water is heated up by the hot magma that flows
underneath the ground.

Some researchers
have predicted that the supervolcano will blow its top again, an
event that would cover up to half the country in ash up to 3 feet
(1 meter) deep, one study predicts. The volcano only seems to go
off about once every 600,000 years, though whether it ever will
happen again isn’t known for sure. Recently though, tremors have
been recorded in the Yellowstone area.

Thera –
island of Santorini in the Aegean Sea — sometime between 1645 B.C.
and 1500 B.C.

While the date
of the eruption isn’t known with certainty, geologists think that
with the energy of several hundred atomic bombs in
a fraction of a second. Though there are no written records of the
eruption, geologists think it could be the strongest explosion ever

The island
that hosted the volcano, Santorini (part of an archipelago of volcanic
islands), had been home to members of the Minoan civilization, though
there are some indications that the inhabitants of the island suspected
the volcano was going to blow its top and evacuated. But though
those residents might have escaped, there is cause to speculate
that the volcano severely disrupted the culture, with tsunamis and
temperature declines caused by the massive amounts of sulfur dioxide
it spewed into the atmosphere that altered the climate.

Mount Vesuvius
– Pompeii, Roman Empire (now Italy) – 79

Mount Vesuvius
is a so-called stratovolcano that lies to the east of what is now
Naples, Italy. Stratovolcanoes are tall, steep, conical structures
that periodically erupt explosively and are commonly found where
one of Earth’s plates is subducting below another, producing magma
along a particular zone.

Vesuvius’ most
famous eruption is the one that buried the Roman towns of Pompeii
and Herculaneum in rock and dust in 79, killing thousands. The ashfall
preserved some structures of the town, as well as skeletons and
artifacts that have helped archaeologists better understand ancient
Roman culture.

Vesuvius is
also considered by some to be the most
dangerous volcano
in the world today, as a massive eruption
would threaten more than 3 million people who live in the area.
The volcano last erupted in 1944.

Laki –
Iceland – 1783

Iceland has
many volcanoes that have erupted over the course of history. One
notable blast was the eruption of Laki volcano in 1783.

The eruption
freed trapped volcanic gases that were carried by the Gulf Stream
over to Europe. In the British Isles, many died of gas poisoning.
The volcanic material sent into the air also created fiery
recorded by 18th-century painters. Extensive crop damage
and livestock losses created a famine in Iceland that resulted in
the deaths of one-fifth of the population, according to the Smithsonian
Institution’s Global Volcanism Program.

The volcanic
eruption, like many others, also influenced the world’s climate,
as the particles it sent into the atmosphere blocked some of the
sun’s incoming rays.

the rest of the article

25, 2010

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