Mount St. Helens spews smoke, soot and ash into the sky in Washington state following a major eruption on May 18, 1980. May 18, 2015, is the 35th anniversary of the eruption that killed more than 50 people and blasted more than 1,300 feet off the mountain's peak.

A camper containing two victims of the Mount St. Helens eruption sits amidst the gray landscape about 8 miles from the mountain on May 26, 1980. Markings in the volcanic ash in front of and behind the camper were left by a helicopter and a searcher who found the victims.

Mount St. Helens is shown against a backdrop of stars just before sunrise in 2010.

Visitors in 2010 look out a display window at the Johnston Ridge Observatory at Mount St. Helens National Volcanic Monument.

Mount St. Helens erupts on May 18, 1980, sending a plume of ash many miles skyward.

A memorial to those who lost their lives in the May 18, 1980, eruption of Mount St. Helens is shown near the Johnson Ridge Observatory.

Andy Setlow goes for a run near Moscow, Idaho, while wearing a mask to avoid breathing ash from the eruption of Mount St. Helens more than 350 miles away.

Viewed from the air, trees knocked down by the May 18, 1980, eruption of Mount St. Helens along a logging road near the south fork of the Toutle River in Washington state.

A tree stump in front of snow-covered Mount St. Helens in 2010.

A worker at an auto dealership in Moscow, Idaho, uses a blower to remove ash from a car after the 1980 eruption of Mount St. Helens, more than 350 miles away.

Participants in a Mount St. Helens Institute guided hike head up the trail to lip of the crater on July 20, 2013.