SAN FRANCISCO,
Dec 15 (Reuters) - Scientists said on Friday they were stepping
up research into the global threat posed by massive volcanic eruptions
-- devastating and inevitable explosions of magma, ash and gas
that promise to have severe and lasting impact on the world"s
climate. "The risk of volcanic eruptions to human populations
is not very well defined," William Rose, a geologist at Michigan
Technological University, told a news briefing at the American
Geophysical Union.
"But
the probability of very large eruptions is probably significantly
higher than that of meteor impact." At a symposium held at
the AGU meeting, volcanologists, atmospheric scientists and other
specialists have launched an effort to begin modeling the impact
of severe volcanic eruptions, which potentially could be many
times larger than the worst experienced in recorded human history.
The most powerful
recent eruption, Philippine volcano Mt Pinatubo, exploded with
astonishing force in 1991 killing 800 people and forcing thousands
to evacuate. Pinatubo blasted rock and dust 12 miles (20 km) into
the atmosphere -- leading to measurable changes in world weather
patterns. Other volcanoes have been even more destructive. Tambora,
in Indonesia, blew its top in 1815, killing more than 90,000 people
and venting so much material into the atmosphere that Europe effectively
lost its summer growing season. And historical records indicate
that earlier eruptions were many times more powerful than that.
Hans Graf of the Max Planck Institute for Meteorology in Hamburg,
Germany, said a drive was underway to establish a clearer understanding
of the effects of volcanic explosion on the atmosphere, which
range from venting huge amounts of ozone-damaging chlorine and
bromine compounds to filling the skies with aerosol droplets that
can absorb solar heat. "This leads to dynamic consequences,
like the warming of continents," Graf said. While researchers
are only beginning to understand the potential lasting impact
of volcanic explosions, scientists are growing more confident
of their ability to forecast the deadly explosions more accurately.
"It"s not so much that we expect one technical breakthrough
... there"s a confluence of a lot of things going on that
should improve our ability to make predictions in the next 10
years," Stanford University geophysicist Paul Segall said.
Volcanologists
say the increasing use of satellites to monitor volcanic activity
on Earth will help to refine measurements indicating the build-up
of magma -- often the precursor to a volcanic eruption. This satellite
observation system, which scientists say may develop into a permanent
volcano early warning system covering some 600 potentially active
volcanoes around the world, will help deliver earlier and more
precise notice of volcanic activity -- like the warning delivered
before Pinatubo, which enabled the safe evacuation of tens of
thousands of residents. "Unlike earthquake prediction, we
can actually do something about volcanoes," Segall said.
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