ount St. Helens is situated in southwestern Washington State. Dormant since 1857, it erupted on May 18, 1980, in one of the most violent volcanic eruptions ever recorded in North America.

n explosive steam eruption on March 27, 1980, was followed by alternating periods of inactivity and minor eruption. A severe earthquake on May 18 opened a crack along the mountain's north side. The north slope fell away in an avalanche that was followed by a lateral air blast that carried hot gases, ash, and stone outward more than 12 miles from the summit. Landslides and magma flow flattened surrounding forests and carried debris as far as 17 miles away.

he blast reduced the volcano's height by about 1,300 feet. A second major eruption occurred on May 25, 1980 and magma formed a volcanic dome in the resulting crater. The eruptions caused approximately 57 deaths. After another eruption in April 1981, experts anticipated that the volcano would remain active for some 20 years.

ount St. Helens National Volcanic Monument covers about 110,000 acres, and there it is illegal to assist with the regeneration of nature. Areas outside the monument, however, have been replanted with trees.

Excerpted from Comptons Interactive Encyclopedia.... Copyright 1993, 1994 Comptons NewMedia, Inc.

A small explosive event at Mount St. Helens volcano began at approximately 5:25 p.m. PST. Pilot reports indicate that the resulting steam-and-ash plume reached an altitude of about 36,000 feet above sea level within a few minutes and drifted downwind to the east-northeast. The principal event lasted about 30 minutes with intensity gradually declining throughout. The USGS Cascades Volcano Observatory lost radio signals from three monitoring stations in the crater soon after the event started. The cause of the outage wont be known until scientists can visit the crater to assess the situation, weather permitting. The event followed a few hours of slightly increased earthquake activity that was noted but not interpreted as precursory activity. There were no other indications of an imminent change in activity.