After 6 months of activity, Mount St. Helens still poses potential hazards to the surrounding region, according to a recent report from the U.S. Geological Survey. Among the hazards that remain are explosive lateral and vertical eruptions, flows of hot pyroclastic rock debris, and floods and mudflows triggered by heavy precipitation.
Most explosive eruptions probably will be preceded by several hours of earthquake and other seismic activity, say USGS hazard coordinators Dwight R. Crandell and Donal R. Mullineaux. It is possible, however, for eruptions to begin with little or no warning, they caution. Seismic activity would allow time for issuing some warnings to the surrounding populace.