Twenty years ago, Mt. St. Helens, in Washington State, "blew." It was the volcano's first eruption in recorded time, although as early as 1978 a team of scientists from the US Geological Survey had labeled it "the most dangerous volcano in the Cascade Range." In June 1991, Mt. Pinatubo in the Philippines spewed forth its own mix of ash, gases, mud, lava, and all the other debris that had been building within the mountain for centuries. Between those two events, USGS scientists had been working at warp speed to learn more about predicting violent eruptions. Data from the nation's only Volcano Center was not helpful. Work there centered on volcanoes that responded to interior pressure by quietly releasing a slow-moving flow of lava, rather than spewing its entrails out in a blast. Survey members were presented with a rare opportunity when Mt. St. Helens showed signs of activity. Camped on the mountains flanks, daring the crater itself, they dug out rocks, tended recorders, began to learn how to use newly developed instruments. Here was an active volcano, believed to be on the verge of eruption by some, if not all, experts. Along with new instruments they had computer programs that saved them days and weeks of work. They learned techniques that revealed the dates of previous major eruptions and provided patterns for future predictions. After the eruption, studying Mt. St. Helens and other volcanoes, they learned more and more. By the time a newly-active Pinatubo threatened tens of thousands of villagers and the U.S. military's Clark Air Force Base, the men of the USGS were far better able to feel secure in urging local authorities and the Air Force brass to evacuate. It was still a gamble, but the odds were far better. And the work goes on. Thompson, a veteran science reporter for Time Magazine, spent many hours with the relative handful of scientists whom he calls "volcano cowboys." (Considering their lifestyle and their rugged "laboratories" - the volcanoes themselves -- the sobriquet is earned.) They have loaned him their field notes, and one geologist gave him his as yet unpublished autobiography. The vivid material and Thompson's skill in bringing a good story to life has resulted in a book that celebrates these "cowboys" their tough and hazardous lives and the often harrowing decisions they must make.Thompson, Dick is the author of 'Volcano Cowboys' with ISBN 9780312208813 and ISBN 0312208812.