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Forecasting Vulcan's Fury
| Article
# : |
19719 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
9 / 1991 |
3,117 Words |
| Author
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Marc J. Defant
Marc J. Defant is professor of geology at the University of
South Florida. He specializes in the study of volcanoes and is
the author of Voyage of Discovery: From the Big Bang to the
Ice Ages, a panoramic history of the universe, including our
galaxy, solar system, and planet. |
Predicting any natural phenomenon is a fairly tricky business. Whether the subject be earthquakes, volcanic eruptions, or global climate change, scientists have continually called for caution and have stressed the need for testing new and often controversial hypotheses.
Predicting a volcanic eruption is a particularly inexact science because of the immense number of variables that play a role as the mountain comes to life. Whether or not a volcano is ready to erupt depends on the volume, temperature, and composition of the magma (the hot molten rock), the pressure and temperature of the gases, and the strength of the overlying rock. The aspects that can be measured take time, and even taking such measurements can be risky because the mountain being measured might explode at any time.
The difficulties of prediction give rise to other risks that have little to do with the science involved. These risks exist because the predictions are based on probability (educated guesses, if you will). The first involves a credibility gap that sometimes develops between scientists and the media. This happens because of false predictions that are sometimes made by amateurs who have been elevated to "expert" status, also by the media. The second concerns forecasts made by competent geologists that call for the implementation of emergency plans when there is a high probability of an "event." Local government officials are frequently unsure of what action to take and when to take it. The high costs and the adverse political problems associated with evacuating populations when there is a false alarm usually inhibit decision making.
Geologists know that more than 1,300 volcanoes have erupted over the last 10,000 years. According to Robert Tilling, a volcanologist with the U.S. Geological Survey, there are about 600 active volcanoes around the world today (active being defined as those that have erupted at some time during recorded history). Approximately 10 percent of the world's population lives on or near these volcanoes. The potential for major disasters is great, and large segments of the population could be annihilated. Over the last 1,000 years, more than 300,000 people have died from volcanic eruptions, and the number of deaths, despite better warning systems, increases each year on the average. Consider the 1815 eruption of Tambora volcano in Indonesia, that killed 92,000 people. Many more people would have died if Tambora had erupted in this century, simply because of the larger population in the region today. Tilling recently stated that "the scientific community and the civil authorities face a chronic and increasingly acute
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