Mount St. Helens erupts

May 18, 1980

Mount St. Helens is an active volcano in the Cascade Mountains of the Washington state in the northwestern United States. It erupted early in the morning on May 18, 1980.

Mount St. Helens is an active volcano in the Cascade Mountains of the Washington state in the northwestern United States. It erupted early in the morning on May 18, 1980.

Mount. St. Helens is one of the most active volcanoes in the region, but seemed to be asleep to all but the geologists. It had erupted in the early to mid-1800’s and was known to only occasionally blow steam an smoke. In March, 1980, an earthquake shook the region, setting in motion changes in the volcano that would reach a critical point on May 18.

At 8:32am, an earthquake triggered an avalanche that released superheated steam, which blasted the surrounding rock into a “stone wind” that traveled down the mountain at 200 miles an hour, flattening everything in its path. That was followed by an eruption of rock and ash from the top of the mountain that lasted for nine hours.

By the following morning, Mt. St. Helens was 1,200 feet shorter than it had been the day before. Geologists estimate that three-quarters of a cubic mile had been blasted from the mountain.

In 1982, Congress set aside 11,000 acres around the mountain as the Mount St. Helens National Volcanic Monument. Within the park, the environment is being allowed to recover naturally, allowing scientists to study the process.