In some cases the answer is yes, but specific predictions require more and different kinds of information. Using seismometers and other sensitive monitoring instruments, USGS scientists are keeping an eye on more than three dozen dangerous volcanoes in the western United States. At the first sign of trouble they’ll intensify their monitoring efforts. Taking the pulse of a restless volcano in this way allows scientists to refine their assessment of hazards and make increasingly specific statements about future activity, including the time, location, and type of activity expected. For example, USGS scientists correctly predicted days in advance more than a dozen dome-building eruptions at Mount St. Helens during 1980-1986. In 1991, an accurate prediction of the largest eruption on Earth in almost 80 years saved thousands of lives and millions of dollars worth of property near Mount Pinatubo in the Philippines.