Scientists Study Threat Of
Gigantic Volcanic Eruptions
SAN FRANCISCO (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 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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