Word: volcanoe
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...hardware, ranging from satellites to acoustical sensors to highly sensitive gas sniffers. Whether the technology is up to the task of monitoring not just one peak but hundreds worldwide, though, is impossible to say, but the question is becoming pressing. "Someday," says Robert Tilling, chief scientist of the USGS Volcano Hazards Program, "one of these mountains will erupt on a scale many orders of magnitude greater than mankind has ever seen...
...volcanologically untutored, there are worse ways to learn what a volcano looks like than to see Dante's Peak. Though the story line is standard disaster-film fare, the science is generally sound. As the movie reveals, the first debris disgorged by a volcano is often a great gray mass of ash. The opaque cloud, made of pulverized rock and glass, falls like concrete snow on land and buildings miles away and may blot out the sun for days...
After the ash, some volcanoes produce what is known as a pyroclastic flow, a ground-hugging cloud of superheated gas and rock that forces a cushion of air down the mountainside at up to 100 m.p.h., incinerating anything in its path. Other mountains spew that signature substance of the volcano: lava. (On this point Dante's Peak was wide of the scientific mark, concocting a fictitious mountain that produces both substances.) Lava moves at speeds ranging from less than 1 m.p.h. to 60 m.p.h...
Chouet is not the only researcher who's using the orbital high ground to study the volcanic underground. In Alaska, USGS researchers have placed satellite receivers at different points on the sloping side of the Augustine volcano and tuned them also to the gps. Like any volcanic mountain, Augustine is swelling slightly as it fills with magma. The degree of this deformation--as calculated by the gps--can help determine the imminence of the eruption. Elsewhere, scientists are leasing time on European or Japanese satellites to take photos of volcanic peaks as they undergo a seismic event like an earthquake...
...magma rises in a volcano, light molecules like carbon dioxide bleed off more than heavier gases like sulfur dioxide. The higher the CO[2] levels, the likelier an eruption. If magma gets stuck in the gullet of the mountain, SO[2] predominates. The more SO[2], the more stagnant the magma and the less probable an eruption. The problem is that taking accurate measurements may require climbing almost directly into a volcano--a decidedly dangerous proposition...