The violence and size of a
volcano’s eruption is
expressed by the Volcanic
Explosivity Index (VEI).
Values for the VEI range from
0 to 8, and are based on:
1.
the volume of material
(lava and particles)
erupted
2.
the height of the eruption
column
3.
how long the eruption
lasts
The larger the VEI value, the
larger the eruption.
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Mt. Vesuvius, the active
volcano that looms over the
Bay of Naples in southern Italy,
has erupted well over 30 times
that we know of.
In A.D. 79, when a two day
eruption of lava and ash
covered the cities of Pompeii
and Stabiae in ash. The ash
left behind solid rock casts of
its victims.
The temperature of the
eruption was under 200°,
therefore, people here
suffocated and were then
buried in the violent ash.
The total number of Vesuvius'
victims will most likely never
be known, but archeologists
are aware of at least 1,000.
The city of Herculean was hit
suddenly by the pyroclastic
flow while waiting to escape in
Herculaneum
the boat house. There bones
The Eruption of Mt.
remain where they died in
second hundreds of years ago. Vesuvius 79AD
Herculaneum
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Mount Pelée, standing more than 4,500 feet
high on the French Caribbean island of
Martinique, erupted violently in May 1902,
killing nearly 30,000 people — effectively
the entire port city of St. Pierre.
The catastrophe was so devastating that
the term nueer dante or glowing cloud that
is now known as a pyroclastic flow.
There had been warnings of steam, light
earth shocks and raining ash, but they
were ignored. After the town was wiped
out, Pelée went dormant for some months,
until geologists discovered a lava dome,
dubbed the tower of Pelée, that rose to
more than 1,000 feet above the crater floor
before eventually crumbling in March
1903.
25 year old Louis Auguste Cyparis a
convicted felon who injured his friend with
a glass during the bar fight. Interestingly,
Louis escaped the jail night before the
eruption, but he reported himself to the jail
the very next morning. He survived
because his dungeon cell had poor
ventilation.
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In 1883, the volcano on the
Indonesian island of Krakatoa
erupted with 13,000 times the
power of an atomic bomb.
The sound of the spewing smoke
and rock was reportedly heard
thousands of miles away, as far as
islands off the eastern coast of
Africa.
Hundreds in a nearby Sumatran
town died almost instantly when by
the pyroclastic flow that was so
powerful that it moved over the
ocean to incinerate other islands
A 100ft tsunami was generated as
the massive earthquakes from the
eruption caused 1/3 of the island to
crumble into the sea.
An estimated 36,000 or so perished
in total. Krakatoa itself then
slumped into the boiling depths of
the ocean, but a new island at the
site was spotted in 1927, and it still
occasionally spits lava into the sky.
It's been dubbed Anak Krakatoa, or
Child of Krakatoa.
Anak Krakatau
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When Mount Pinatubo erupted in 1991,
the amount of sulfuric gas and ash it sent
into the stratosphere cooled global
ground temperatures by 1°F for the next
two years.
A year before the eruption, a 7.8magnitude earthquake struck about 60
miles northeast of Pinatubo, causing
landslides and an increase in steam
emissions from one of the volcano's
geothermal areas, ultimately setting the
stage for the 1991 explosion.
While the eruption resulted in more than
700 deaths (mostly from collapsed
structures due to ash accumulation the
roofs), many scientists predicted the
explosion, thus saving the lives of an
estimated 5,000.
Still, the eruption produced one of the
most dramatic environmental scenes
ever witnessed. With ash that rose 22
miles into the sky, it is considered the
second largest volcanic eruption of the
20th century.
Full documentary of the eruption of
Pinatubo 1991
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Mount St. Helens was getting ready to
burst for nearly two months before it
exploded, not to mention the more than
120 years it lay dormant.
While the eruption was anticipated, the
manner in which it occurred was
completely unprecedented. At 8:32 a.m.
on May 18, 1980, a 5.1-magnitude
earthquake triggered a sideways blast out
of a dome on the side of the eruption.
Scientists were caught of guard and were
actually taking readings on the volcano
when it erupted.
It generated a pyroclastic flow of at least
300 m.p.h. that incinerated over 250miles
of forest.
About an hour later, the volcano created a
massive lahar that buried towns and was
moving as fast as 90mph.
At the same time, a mushroom-shaped
plume of ash shot 16 miles into the air,
eventually covering three states.
Complete darkness blanketed Spokane,
Wash., a city about 250 miles northeast of
the volcano. When the ash came down it
fell in the form of black rain that literally
coated the residents of Washington, Idaho
and parts of Montana with a fine gray
powder. Fifty-seven people and thousands
of animals were killed, and some 200
square miles of trees were obliterated.
Video of the
eruption of Mt.
Saint Helens
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The Volcanic Explosivity Index
goes up to 8. On that scale, the 1815
eruption of Mount Tambora rates a
very destructive 7.
The explosion took place on the
island of Sumbawa (then in the
Dutch East Indies, now in
Indonesia) and plunged the region
into darkness, but its effects were
anything but isolated.
Tens of thousands of people were
killed by the massive pyroclastic
flow, subsequent tsunamis and later
by the ensuing starvation and
disease.
The largest volcanic eruption in
recorded history changed the
world's climate so much (even
crops in Europe and North America
failed) that 1816 became known as
"the year without a summer.“
Tambora itself shrank several
thousand feet and traded its peak
for a massive crater at its summit.
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Nov. 13, 1985, a relatively small
explosion unleashed floods that
swept away 1,500 people on one
side of the mountain. On the other
side was the town of Armero, the site
of the worst destruction. 25-m.p.h.
lahars obliterated the town and
blanketed it in gray muck. When the
landslides subsided, 23,000 people
had died and damage was
estimated at $1 billion — one-fifth of
Colombia's GNP at the time.
The eruption was small, in volcanic
terms, that is, producing only about
3% of the ash ejected by Mount St.
Helens in 1980.
Instead, it was the lahars that made
Colombia's 1985 Nevado del Ruiz
explosion the second deadliest in
the 20th century and the fourth
deadliest in recorded history. The
volcano has been blowing its top
since the Pleistocene era and has
erupted three times in modern
history, including in 1595 and 1845.
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The Toba eruption occur 75,000 years ago in India. This
super volcano caused for a dramatic loss of human and
animal. New research is showing the eruption may
have been massive enough to spark an Ice Age,
reducing global temperature 3-3.5degree, causing for
even more loss of life.
According to the Toba catastrophe theory, a massive
volcanic eruption changed the course of human history
by severely reducing the human population.
This may have occurred when around 70–75,000 years
ago the Toba caldera in Indonesia underwent a
category 8 or "mega-colossal" eruption on the Volcanic
Explosivity Index.
This massive environmental change is believed to have
created population bottlenecks in the various species
that existed at the time.
This in turn accelerated differentiation of the
isolated human populations, eventually leading to
the extinction of all the other human species except
for the branch that became modern humans.