Nova Episodes on PBS

“Volcano's Deadly Warning” explores a seismic shift in the way scientists predict eruptions. The new method: reading seismic signals indicating magma and gas buildup in active volcanoes. “Suddenly you realize that the volcano is speaking to you,” says Bernard Chouet of the U.S. Geological Survey, who developed the method. The hour looks at how it worked in predicting eruptions in Alaska and Mexico. In Colombia, however, a scientist who used a different method almost died---and a number of his colleagues did---when a volcano erupted on them in 1993.