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Landslide on the flank of a small drainage in Northwest Seattle.
December 31, 1997

LS - Seattle

Landslide on the flank of a small drainage in northwest Seattle. Foundation of house on right edge of photograph and decks of neighboring houses were undermined.

Angle and distance measurements to the Mount St. Helens' flanks wer...
May 15, 1989

Angle and distance measurements to Mount St. Helens' flanks were ta...

Angle and distance measurements to the Mount St. Helens' flanks were taken periodically to monitor for deformation similar to the 1980 bulge. Station northeast of volcano.

Deformation measurements on the Mount St. Helens' dome; three geolo...
April 18, 1988

Deformation measurements on the Mount St. Helens' dome; three geolo...

Deformation measurements on the Mount St. Helens' dome; three geologists in middle bottom of this aerial photograph.

Dome building eruption at Mount St. Helens—30-minute, moon-lit expo...
October 22, 1986

Dome building eruption at Mount St. Helens—30-minute, moon-lit expo...

The last dome-building eruption of Mount St. Helens during the 1980s occurred in October 1986. A new lobe was extruded, increasing the dome's height to 925 feet (282 meters), making it taller than a 77-story building. In volume, the dome was nearly 40 times the size of Seattle's Kingdome stadium. The view is from Harry's Ridge, five miles (8 kilometers) north of the

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View of the Spirit Lake outlet tunnel, built in 1985, that allows w...
October 2, 1986

View of the Spirit Lake outlet tunnel, built in 1985, that allows w...

View of the Spirit Lake outlet tunnel, built in 1985, that allows water to drain out of Spirit Lake safely and maintain the lake's water level 100 ft (30 m) below the estimated overtopping level.

Lava dome in Mount St. Helens' crater as viewed from the "Deepthroa...
August 12, 1985

Lava dome in Mount St. Helens' crater as viewed from the "Deepthroa...

The lava dome was taller than a 66-story building and almost as wide as the length of nine football fields. The dome completely fills the camera's field of view. Compare with image taken August 22, 1981 from the same location with the same camera.

Mount St. Helens four years after the May 18, 1980 eruption—lava do...
September 24, 1984

Mount St. Helens four years after the May 18, 1980 eruption—lava do...

Mount St. Helens four years after the May 18, 1980 eruption—lava dome in the crater and drainage channels development on flanks; view from Johnston Ridge.

Fireweed, growing in Mount St. Helens' devastated area; view from t...
August 15, 1984

Fireweed, growing in Mount St. Helens' devastated area, Summer 1985

Vegetation began reappearing as early as the summer of 1980 as many small trees and plants were protected by the snowpack on May 18. Seeds, carried by the wind or by animals, also entered the area and grew. By 1985, the ridges surrounding the volcano were covered with new growth.

Measurements of the magnetic field surrounding the Mount St. Helens...
June 18, 1984

Measurements of magnetic field surrounding the Mount St. Helens' dome

The strength of the magnetic field increased as the dome cooled and magnetic minerals formed. During the eruptions the strength usually changed rapidly as magma heated and deformed the dome.

Harry's Ridge monitoring station, 8 km (5 mi) north of Mount St. He...
March 22, 1984

Harry's Ridge monitoring station, 8 km north of Mount St. Helens

Harry's Ridge monitoring station, 8 km (5 mi) north of Mount St. Helens' crater.

Castle Lake formed as a result of the Mount St. Helens' May 18, 198...
March 15, 1984

Castle Lake formed as a result of the Mount St. Helens' May 18, 198...

The May 18, 1980 debris avalanche from Mount St. Helens covered over 24 square miles (62 square kilometers) of the upper Toutle River valley and blocked tributaries of the North Fork Toutle River. New lakes such as Castle Lake (pictured here) and Coldwater Lake were created.