Timeline of Eruption and Regrowth

Although the 1980 eruption of Mount St. Helens could not have been predicted to an exact day or time, scientists were continuously studying the surrounding area. An earthquake in March 1980, alerted volcanologists to the fact that an eruption would soon occur.

Click through the timeline to view images and read details of events that occurred before, during, and after the 1980 eruption starting with the 4.1 magnitude earthquake on March 20, 1980 and ending at the present day. The effects of the eruption are still being felt today, 40 years later.

MARCH 1980

MARCH 20, 1980 Two months prior to the May 18 eruption, a 4.1 magnitude earthquake is recorded beneath Mount St. Helens. This is the first recorded warning sign of the upcoming blast. MARCH 25-26, 1980 Over 170 earthquakes – most with a magnitude of 2.0 or less – are recorded under Mount St. Helens. That is 3.5 earthquakes per hour over a 48 hour period. MARCH 27, 1980 Mount St. Helens erupts for the first time in over 100 years. The escaped steam from the volcano creates a 75m (250ft) crater through the volcano’s ice cap. MARCH 30, 1980 93 explosions of steam and ash are recorded in a single day. That is approximately one eruption every 15 minutes.   Click here to continue on to the next section of the timeline Return to timeline.

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APRIL 1980

APRIL 1-4, 1980 Small eruptions of steam and ash continue. Some plumes reach up to 16,000ft in the atmosphere. APRIL 7, 1980 From the continuous eruptions and earthquakes, the crater’s dimensions grow to approximately 1700ft long by 1200ft wide. APRIL 27, 1980 A small bulge is noted at the Goat Rocks dome on the North side of the mountain. The bulge is caused by trapped magma and gas underneath the surface. Eruptions and earthquakes still…

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MAY 1-17, 1980

MAY 7, 1980 2,550 earthquakes with a magnitude of 3.0 or greater are recorded since the first earthquake on March 20. 291 earthquakes with a magnitude of 4.0 or greater are also recorded. MAY 14, 2980 The Goat Rock bulge continues to grow outwards at about 5ft per day and a total of 450ft. The bulge was prominent and visible to the naked eye. Underneath, trapped magma continues to build up. MAY 17,1980 One day before the eruption, Gov. Dixy Lee Ray allows property owners limited entry into the Red Zone to check on their houses and collect any items left behind. Police escorted approximately 50 people to their homes and back. Click here to continue on to the…

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MAY 18, 1980

                  MAY 18, 1980, 8:32AM A 5.1 magnitude earthquake occurs at the summit, triggering landslides on the northern side of the mountain. This is the largest avalanche to ever be recorded. Lateral blasts (eruptions that take place on the side of a volcano) accelerate the debris from the avalanche to more than 300mph. MAY 18, 1980, 8:35AM Lightning storms caused by charged ash particles in the air begin to occur around Mount St. Helens. Pyroclastic flow containing a mixture of hot ash, lava, gases, and debris rushes from the mountain toward Spirit Lake and most of the northern side. Because of the high speeds and amount of debris from the blast, most life in the area is wiped out. MAY 18, 1980, 11:15AM Mudflows containing a mixture of sediment, trees, and ash surge down Toutle River. Intense rapids and flooding occurs within the area. This event will eventually alter the Toutle River permanently. May 18, 1980 The volcanic blast from Mount St. Helens levels all plant and animal life in the blast zone. Harry R. Truman and the Mount St. Helens Lodge on…

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MAY 19-31

MAY 19, 1980, 6:28PM Spirit Lake’s shoreline is recorded to be 150ft higher than normal. The rise in water level is caused by the large amounts of trees and other debris that have sunk to the bottom of the lake. MAY 22, 1980 President Jimmy Carter visits Washington to see the devastation from Mount St. Helens. He declares the area a state of…

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JUNE-OCTOBER 1980

JUNE 12, 1980 Two eruptions occur, creating plumes of ash reaching 10 miles high. JUNE-OCTOBER 1980 Other, infrequent eruptions occur, destroying the lava domes in the crater. A third dome begins to grow. Click here to continue on to the next section of the timeline. Click here to return to the previous section of the timeline. Return to timeline.

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1980-1982

1980-PRESENT Despite the destruction and seeming desolation from the May 18th 1980 eruption, biological legacies survive and set the direction for an entirely new ecosystem. These legacies include ants, insects, moss, dwarf brambles, and several other plants and shrubs. Several lakes also survive the blast due to ice and snow coverage. 1980-PRESENT North America’s youngest glacier, Crater Glacier begins to form from the accumulation of ice and snow inside the crater caused by the eruption. June 1982 Scientists spot Prairie Lupine, the first plant seen for miles in the Pumice Plains. 1982 110,000-acre Mount St. Helens National Volcanic Monument is established by President Reagan. Click here to continue on to the next section of the timeline. Click here to return to the previous section of the timeline. Return to timeline.

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1986-1987

1986 Mount St. Helens begins to lie dormant. 1987 Volcano summit reopens for recreational climbing. 1987 U.S. Army Corps of Engineers begin building a dam to hold back sediment carried downstream by the North Fork of the Toutle.   Click here to continue on to the next section of the timeline. Click here to return to the previous section of the timeline. Return to timeline.

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1994-2004

1994 The reconstructed 52-mile-long Spirit Lake Memorial Highway opens to traffic, connecting Castle Rock to inside the blast zone. 1997 The U.S. Forest Service opens the Johnston Ridge Observatory five miles from the crater. SEPTEMBER-OCTOBER 2004 Several earthquakes awaken the mountain, and continued tremors inside the mountain indicate movement of magma. The Forest Service evacuates visitors from Johnston Ridge Observatory in October. Click here to continue on to the next section of the timeline. Click here to…

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2004-2005

OCTOBER 11 – NOVEMBER 5, 2004 Lava emerges on the crater surface for the first time in 18 years, a new dome at the summit forms, reaching 26 million cubic yards. JANUARY 16, 2005 A 17-minute explosive eruption destroys instruments inside the crater. MARCH 8, 2005 The mountain sends ash and steam to an altitude of 36,000 feet   . Click here to continue on to the next section of the timeline. Click here to return to the previous section of the timeline. Return to…

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2005-Present

2005 More than 150 species of wildflowers, shrubs and trees, with an average of ten new plant species gaining a foothold every year appear in the blast zones. 2008 Dome growth slows to a halt and seismic activity drops. Scientists declare that the 2004-2008 eruption has ended after building a new, 125-million-cubic-yard lava dome. 2012-Now Life is resilient, it is impossible to return to the ecosystem from before the eruption, but there is a new ecosystem taking hold of Mount St Helens. Elk populations have reached a record high, prairie style plant and insect populations have taken root, and Spirit Lake is reforming and returning the landscape to a different sort of glory. Click here to return to the previous section of the timeline. Return to timeline.

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Mount St. Helens, Summer 1980
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