The prediction of volcanic eruptions is difficult because, to be of practical use, they must be made before eruptions! Its a lot easier to see patterns in monitoring data after an eruption has occurred. But great progress has been made because of the lessons learned over many years at Kilauea volcano in Hawaii, and applied and modified at Mt. St. Helens before and during in eruption sequence in the 1980s.

Meaningful prediction requires careful monitoring of a volcano’s vital signs. Seismometers can be used to pinpoint earthquakes which track the rise of magma and its movement along fissures. Measurements of the tilt of the entire mountain provide additional information about the “breathing” of the volcano as magma moves inside it. Instruments that sniff SO2, CO2 and other gases also can signal changes in the volcano. At some volcanoes the seismic information seems most reliable, at others the tilt tells the story. But the best predictions come from the combination of all of these methods into a volcano monitoring and prediction system.Volcanologists use many different kinds of tools including instruments that detect and record earthquakes (seismometers and seimographs), instruments that measure ground deformation (EDM, Leveling, GPS, tilt), instruments that detect and measure volcanic gases (COSPEC), instruments that determine how much lava is moving underground (VLF, EM-31), video and still cameras, infrared cameras, satellite imagers, webcams, etc!