Katla is attracting attention,
although it is still early. The concern
here is that this particular volcano is able to make a very large mess unlike
last years round of activity.
Our problem is that we have no
solution to this type of problem at all and past events in Iceland have been devastating to
both animals and humans.
The evidence to date informs us
that magma is moving and one assumes that the longer this goes on the more
violent the final event although we do not even know that for sure. Simply put, the kettle is surely brewing and
the release will be violent.
The one prediction that we can
make is that this eruption will cause a massive ash cloud and impact weather in
Northern Europe .
New Icelandic volcano eruption could have global impact
By Jane O'BrienBBC News, Reykjavik
1 December 2011 Last updated at 21:16 ET
Ford Cochran says there have been 500 or so tremors in and around the
caldera of Katla in October
Hundreds of metres under one of Iceland 's largest glaciers there
are signs of a looming volcanic eruption that could be one of the most powerful
the country has seen in almost a century.
Mighty Katla, with its 10km (6.2 mile) crater, has the potential to
cause catastrophic flooding as it melts the frozen surface of its caldera and
sends billions of gallons of water surging through Iceland 's
east coast and into the Atlantic Ocean .
"There has been a great deal of seismic activity," says Ford
Cochran, the National Geographic's expert on Iceland .
There were more than 500 tremors in and around the caldera of Katla
just in October, which suggests the motion of magma.
"And that certainly suggests an eruption may be imminent."
Scientists in Iceland
have been closely monitoring the area since 9 July, when there appears to have
been some sort of disturbance that may have been a small eruption.
Eruption 'long overdue'?
Even that caused significant flooding, washing away a bridge across the
country's main highway and blocking the only link to other parts of the island
for several days.
"The 9 July event seems to mark the beginning of a new period of
unrest for Katla, the fourth we know in the last half century," says
Professor Pall Einarsson, who has been studying volcanoes for 40 years and
works at the Iceland University Institute of Earth Sciences.
“It means you actually see the
crust of the earth ripping apart”
Ford CochranIceland expert, National Geographic
"The possibility that it may include a larger eruption cannot be
excluded," he continues.
"Katla is a very active and versatile volcano. It has a long
history of large eruptions, some of which have caused considerable
damage."
The last major eruption occurred in 1918 and caused such a large
glacier meltdown that icebergs were swept into the ocean by the resulting
floods.
The volume of water produced in a 1755 eruption equalled that of the
world's largest rivers combined.
Thanks to the great works of historic literature known as the Sagas, Iceland 's
volcanic eruptions have been well documented for the last 1,000 years.
But comprehensive scientific measurements were not available in 1918,
so volcanologists have no record of the type of seismic activity that led to
that eruption.
All they know is that Katla usually erupts every 40 to 80 years, which
suggests the next significant event is long overdue.
Eyjafjallajokull's relatively small eruption in 2010 halted air traffic
across Europe
Katla is part of a volcanic zone that includes the Laki craters. In
1783 volcanoes in the area erupted continuously for eight months, generating so
much ash, hydrogen fluoride and sulphur dioxide that it killed one in five
Icelanders and half of the country's livestock.
"And it actually changed the Earth's climate," says Mr
Cochran.
"Folks talk about a nuclear winter - this eruption generated
enough sulphuric acid droplets that it made the atmosphere reflective, cooled
the planet for an entire year or more and caused widespread famine in many
places around the globe.
"One certainly hopes that Katla's eruption will not be anything
like that!"
The trouble is scientists do not know what to expect. As Prof Einarsson
explains, volcanoes have different personalities and are prone to changing
their behaviour unexpectedly.
"When you study a volcano you get an idea about its behaviour in
the same way you judge a person once you get to know them well.
"You might be on edge for some reason because the signs are
strange or unusual, but it's not always very certain what you are looking at.
We have had alarms about Katla several times."
Changing climate
He says the fallout also depends on the type of eruption and any number
of external factors.
"This difficulty is very apparent when you compare the last two
eruptions in Iceland
- Eyjafjallajokull in 2010 and Grimsvotn in 2011.
"Eyjafjallajokull, which brought air traffic to a halt across
Europe, was a relatively small eruption, but the unusual chemistry of the
magma, the long duration and the weather pattern during the eruption made it
very disruptive.
"The Grimsvotn eruption of 2011 was much larger in terms of volume
of erupted material.
"It only lasted a week and the ash in the atmosphere fell out
relatively quickly.
"So it hardly had any noticeable effect except for the farmers in
south-east Iceland
who are still fighting the consequences."
Of course, volcanoes are erupting around the world continuously.
Scientists are particularly excited about an underwater volcano near El Hierro
in the Canary Islands , which is creating new
land.
But Iceland
is unique because it straddles two tectonic plates and is the only place in the
world where the mid-Atlantic rift is visible above the surface of the ocean.
"It means you actually see the crust of the earth ripping
apart," says Mr Cochran. "You have an immense amount of volcanic
activity and seismic activity. It's also at a relatively high latitude so Iceland
is host to among other things, the world's third-largest icecap."
But the biggest threat to Iceland 's icecaps is seen as
climate change, not the volcanoes that sometimes melt the icecaps.
They have begun to thin and retreat dramatically over the last few
decades, contributing to the rise in sea levels that no eruption of Katla,
however big, is likely to match.
No comments:
Post a Comment