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Dredging of the Toutle River after the Mount St. Helens 1980 erupti...
February 5, 1981

Dredging of the Toutle River after the Mount St. Helens 1980 erupti...

U.S. Army Corps of Engineers preformed dredging projects on the Toutle, Cowlitz, and Columbia Rivers and by 1987 enough material had been removed to build a 12 lane highway, one-foot thick from New York, NY to San Francisco, CA.

Lava dome growing within the Mount St. Helens crater reaches 34 m (...
October 24, 1980

Lava dome growing within the Mount St. Helens crater reaches 34 m (...

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.

Lahars resulting from the May 18, 1980 eruption of Mount St. Helens...
October 23, 1980

Lahars resulting from the May 18, 1980 eruption of Mount St. Helens...

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.

Bear tracks found on Mount St. Helens in an ash and pumice deposite...
October 15, 1980

Bear tracks found on Mount St. Helens in an ash and pumice deposite...

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.

Spirit Lake and the devastated forest area surrounding Mount St. He...
October 4, 1980

Spirit Lake and the devastated forest area surrounding Mount St. He...

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 slopes of Smith Creek valley, east of Mount St. Helens, show tr...
September 24, 1980

The slopes of Smith Creek valley, east of Mount St. Helens, show tr...

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....
September 23, 1980

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

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

Debris avalanche deposit view from the northwest of Mount St. Helen...
September 16, 1980

Debris avalanche deposit view from NW of Mount St. Helens after the...

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
September 10, 1980

Mount St. Helens soon after the May 18, 1980 eruption

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 fr...
September 10, 1980

Mount St. Helens soon after May 18, 1980 eruption

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

Pyroclastic flow from the August 7, 1980 eruption stretches from Mo...
August 7, 1980

Pyroclastic flow from the Aug. 7, 1980 eruption stretches from Moun...

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. T...
August 7, 1980

Pyroclastic flow during Aug. 7, 1980 Mount St. Helens eruption. The...

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.