During the 9 hours of vigorous eruptive activity on May 18, 1980, about 540 million tons of ash from Mount St. Helens fell over an area of more than 22,000 square miles (57,000 square kilometers).

The generalized map shows the distribution of ash fallout from the May 18 eruption. Prevailing winds distributed the fallout from the ash cloud over a wide region.

2023年3月28日 · Browse the thumbnails below to learn more about the disturbance zones created by the eruption. The May 18, 1980 eruption of Mount St. Helens involved a complex series of events that unfolded over 12 hours, with many events going on simultaneously.

2024年11月27日 · During Mount St. Helens intense nine-hour eruption it sent a 12-mile-high ash cloud into the sky and released 520 million tons of ash. The ash spread across 22,000 square miles, darkening skies and eventually circling the globe within two weeks.

Map showing the extent of ash fall from the three caldera-forming eruptions at Yellowstone during the last 2.1 million years. The ash bed from the 1980 Mount St Helens eruption is shown for comparison. Modified from USGS graphic.

2022年2月21日 · Map covering the immediate area of effect and "Ash Zone" of the Mount St. Helens eruption

A major eruption destroyed the summit of Mt. St. Helens, projected ash into the stratosphere, devastated the N and NW flanks, and killed dozens of people on 18 May. The initial explosion was heard more than 350 km away.

svg map of the 1980 mount st helens ash fallout, info from usgs map: Date: 6 December 2007: Source: Own work: Author: Murraybuckley: Permission (Reusing this file) all rights released: Other versions: png version : ... Description=svg map of the 1980 mount st helens ash fallout, info from usgs map |Source=self-made |Date=6 dec 2007 ...

St. Helens, famous for its explosive 1980 eruption, has long been the most active volcano in the Pacifi c Northwest. U.S. Geologi-cal Survey (USGS) scientists have documented the volcano’s 300,000-year geologic history, including powerful explosions of ash, outpour-ings of lava, and huge landslides and volcanic mudfl ows.

On May 18, 1980, Mt. St. Helens in the state of Washington exploded in a cloud of ash, plus lava and mud flows. What had been a beautiful symmetrical snow-covered mountain with heavily forested slopes became a startling landscape of ash, mud, and downed trees surrounding a broken, irregular peak.