Volcanoes are close cousins of earthquakes, arising as they do from the same powerful motions of the planet's tectonic plates. Despite their fiery reputation for chaos and destruction, however, only about sixty volcanoes erupt each year. What's more,
most volcanoes are on the ocean floor where plate boundaries are converging or spreading over "hot spots"large subterranean pools of magma.
This is not to say that volcanoes pose no peril. Over the last 300 years more than 260,000 people have died from volcanic activity. The 1991 eruption of the Philippines' Mount Pinatubo killed more than 300 people and devastated the area's economy. When Mount St. Helen's blew its stack in the State of Washington in 1980, 57 people died, nearly 7,000 big game animals were killed, more than 12 million salmon perished, forests were devastated, and the economy took a nearly $1 billion hit.
All of this reinforces the need for better ways to model and predict volcanic activity. One way to both study and monitor a volcano is to place a gas sensing device called COSPEC along the volcano's flanks. COSPEC (for "correlation spectrometer") measures how much sulfur dioxide gas is escaping from the volcano's interior. A jump in the amount of sulfur dioxide suggests an imminent eruption. Still, a few hours' or, at most, a few days' warning is the best that scientists can manage with current knowledge and technology. And sometimes, of course, there is no discernible warning at all.
In 1993, nine members of a scientific expedition who were taking gas samples died when a sudden spasm of molten rock and ash erupted from the crater of a volcano called Galeras in Colombia. The tragedy prompted one of the survivors, Stanley Williams of Arizona State University, to organize a conference that would enable scientists to standardize their methods and make data consistent from one volcano observatory to another. The 1997 NSF-funded conference brought together virtually every scientist then working with COSPECsome 25 volcanologists from 14 countries. Williams has also developed a remote-access instrument called GASPEC that measures another early-warning gas, carbon dioxide.
Other volcano-monitoring efforts funded in part by NSF include a network of seismometers (instruments that measure ground vibrations caused by earthquakes) and an array of Earth-orbiting satellites called the Global Positioning System (GPS). The GPS can alert scientists to volcano-related ground deformations at the millimeter scaledeformations that might signal an imminent eruption.