Images

Small phreatic eruption of Mount St. Helens in the spring of 1980, before the May 18, 1980 blast.

This October dome was taller than a nine-story building and wider than the length of three football fields. This dome was not the first dome to grow in the crater. In June and August 1980, two domes formed, only to be blasted away by the explosive events of July 22 and October 16.

Nearly 135 miles (220 kilometers) of river channels surrounding the volcano were affected by the lahars of May 18, 1980. A mudline left behind on trees shows depths reached by the mud.

Many smaller animals, such as gophers, mice, frogs, fish, and insects were hibernating below ground or under water on May 18, 1980, and they survived the blast. Larger animals such as bear (whose tracks are shown here), elk, deer, and coyotes have been moving back into the area as their food supplies increase.

This lake was once surrounded by lush forest and is within the area devastated by the directed blast, covered by ash and tephra, then inundated by pyroclastic flows. Remnants of the forest float on the surface of the lake. Mount Rainier (4,392 m or 14,410 ft) is in the distance. The view is from the south.

The direction of the blast, shown here from left to right, is apparent in the alignment of the downed trees. Over four billion board feet of usable timber, enough to build 150,000 homes, was damaged or destroyed.

Muddy River bridge crossing destruction from May 18, 1980 Mount St. Helens lahars.

After the May 18, 1980 eruption, Mount St. Helens' elevation was only 8,364 feet (2,550 meters) and the volcano had a one-mile-wide (1.5 kilometers) and approximately 600 m (2000 ft) deep horseshoe-shaped crater. View here is from the northwest.

Mount St. Helens soon after the May 18, 1980 eruption, as viewed from Johnston's Ridge.

Mount St. Helens soon after the May 18, 1980 eruption, as viewed from Johnston's Ridge.

During the May 18, 1980 eruption, at least 17 separate pyroclastic flows descended the flanks of Mount St. Helens. Pyroclastic flows typically move at speeds of over 60 miles per hour (100 kilometers/hour) and reach temperatures of over 800 Degrees Fahrenheit (400 degrees Celsius).

Pyroclastic flow during August 7, 1980, Mount St. Helens eruption. The view is from Johnston Ridge, located 8 km (5 mi) north of Mount St. Helens.

July 22, 1980 eruption of Mount St. Helens sent pumice and ash 6 to 11 mi (10-18 km) into the air, and was visible in Seattle, Washington (100 mi/160 km north).

Mudline left on tree by May 18, 1980 lahars from Mount St. Helens near the Old Highway 99 bridge across Toutle River, geologist 6 ft tall.

Ash from the May 18, 1980 eruption of Mount St. Helens covering the ground and road at a farm in Connell, Washington, approximately 300 km (180 mi) from the volcano.

For more than nine hours a vigorous plume of ash erupted, eventually reaching 20-25 km (12-15 mi) above sea level. By early May 19, the devastating eruption was over.

On May 18, 1980, at 8:32 a.m. Pacific Daylight Time, a magnitude 5.1 earthquake shook Mount St. Helens. The bulge and surrounding area slid away in a gigantic rockslide and debris avalanche, releasing pressure, and triggering a major pumice and ash eruption of the volcano. Thirteen-hundred feet (400 meters) of the peak collapsed or blew outwards.

May 18, 1980 eruption of Mount St. Helens from southwest. Note the pyroclastic density currents spilling over the crater rim.

Plinian eruption column from May 18, 1980 Mount St. Helens. Aerial view from the Southwest.

Plinian column from May 18, 1980 eruption of Mount St. Helens. Aerial view from southwest. Mount Adams is in the background (right).

Mount St. Helens on May 17, 1980, one day before the devastating eruption. The view is from Johnston's Ridge, six miles (10 kilometers) northwest of the volcano.