1980 : Mount St. Helens erupts
At 8:32 a.m. PDT, Mount St. Helens, a volcanic peak in southwestern
Washington, suffers a massive eruption, killing 57 people and
devastating some 210 square miles of wilderness.
Called Louwala-Clough, or "the Smoking Mountain," by Native Americans,
Mount St. Helens is located in the Cascade Range and stood 9,680 feet
before its eruption. The volcano has erupted periodically during the
last 4,500 years, and the last active period was between 1831 and
1857. On March 20, 1980, noticeable volcanic activity began again with
a series of earth tremors centered on the ground just beneath the
north flank of the mountain. These earthquakes escalated, and on March
27 a minor eruption occurred, and Mount St. Helens began emitting
steam and ash through its crater and vents.
Small eruptions continued daily, and in April people familiar with the
mountain noticed changes to the structure of its north face. A
scientific study confirmed that a bulge more than a mile in diameter
was moving upward and outward over the high north slope by as much as
six feet per day. The bulge was caused by an intrusion of magma below
the surface, and authorities began evacuating hundreds of people from
the sparsely settled area near the mountain. A few people refused to
leave.
On the morning of May 18, Mount St. Helens was shaken by an earthquake
of about 5.0 magnitude, and the entire north side of the summit began
to slide down the mountain. The giant landslide of rock and ice, one
of the largest recorded in history, was followed and overtaken by an
enormous explosion of steam and volcanic gases, which surged northward
along the ground at high speed. The lateral blast stripped trees from
most hill slopes within six miles of the volcano and leveled nearly
all vegetation for as far as 12 miles away. Approximately 10 million
trees were felled by the blast.
The landslide debris, liquefied by the violent explosion, surged down
the mountain at speeds in excess of 100 miles per hour. The avalanche
flooded Spirit Lake and roared down the valley of the Toutle River for
a distance of 13 miles, burying the river to an average depth of 150
feet. Mudflows, pyroclastic flows, and floods added to the
destruction, destroying roads, bridges, parks, and thousands more
acres of forest. Simultaneous with the avalanche, a vertical eruption
of gas and ash formed a mushrooming column over the volcano more than
12 miles high. Ash from the eruption fell on Northwest cities and
towns like snow and drifted around the globe within two weeks.
Fifty-seven people, thousands of animals, and millions of fish were
killed by the eruption of Mount St. Helens.
By late in the afternoon of May 18, the eruption subsided, and by
early the next day it had essentially ceased. Mount St. Helens'
volcanic cone was completely blasted away and replaced by a
horseshoe-shaped crater--the mountain lost 1,700 feet from the
eruption. The volcano produced five smaller explosive eruptions during
the summer and fall of 1980 and remains active today. In 1982,
Congress made Mount St. Helens a protected research area.
Mount St. Helens became active again in 2004. On March 8, 2005, a
36,000-foot plume of steam and ash was expelled from the mountain,
accompanied by a minor earthquake. Though a new dome has been growing
steadily near the top of the peak and small earthquakes are frequent,
scientists do not expect a repeat of the 1980 catastrophe anytime
soon.
history.com/tdih.do
1860 : Lincoln nominated for presidency
history.com/tdih.do?action=tdihArticleCategory&id=5011
1896 : Supreme Court rules in Plessy v. Ferguson
history.com/tdih.do?action=tdihArticleCategory&id=5012
1974 : India joins the nuclear club
history.com/tdih.do?action=tdihArticleCategory&id=5013
##########################################
At 8:32 a.m. PDT, Mount St. Helens, a volcanic peak in southwestern
Washington, suffers a massive eruption, killing 57 people and
devastating some 210 square miles of wilderness.
Called Louwala-Clough, or "the Smoking Mountain," by Native Americans,
Mount St. Helens is located in the Cascade Range and stood 9,680 feet
before its eruption. The volcano has erupted periodically during the
last 4,500 years, and the last active period was between 1831 and
1857. On March 20, 1980, noticeable volcanic activity began again with
a series of earth tremors centered on the ground just beneath the
north flank of the mountain. These earthquakes escalated, and on March
27 a minor eruption occurred, and Mount St. Helens began emitting
steam and ash through its crater and vents.
Small eruptions continued daily, and in April people familiar with the
mountain noticed changes to the structure of its north face. A
scientific study confirmed that a bulge more than a mile in diameter
was moving upward and outward over the high north slope by as much as
six feet per day. The bulge was caused by an intrusion of magma below
the surface, and authorities began evacuating hundreds of people from
the sparsely settled area near the mountain. A few people refused to
leave.
On the morning of May 18, Mount St. Helens was shaken by an earthquake
of about 5.0 magnitude, and the entire north side of the summit began
to slide down the mountain. The giant landslide of rock and ice, one
of the largest recorded in history, was followed and overtaken by an
enormous explosion of steam and volcanic gases, which surged northward
along the ground at high speed. The lateral blast stripped trees from
most hill slopes within six miles of the volcano and leveled nearly
all vegetation for as far as 12 miles away. Approximately 10 million
trees were felled by the blast.
The landslide debris, liquefied by the violent explosion, surged down
the mountain at speeds in excess of 100 miles per hour. The avalanche
flooded Spirit Lake and roared down the valley of the Toutle River for
a distance of 13 miles, burying the river to an average depth of 150
feet. Mudflows, pyroclastic flows, and floods added to the
destruction, destroying roads, bridges, parks, and thousands more
acres of forest. Simultaneous with the avalanche, a vertical eruption
of gas and ash formed a mushrooming column over the volcano more than
12 miles high. Ash from the eruption fell on Northwest cities and
towns like snow and drifted around the globe within two weeks.
Fifty-seven people, thousands of animals, and millions of fish were
killed by the eruption of Mount St. Helens.
By late in the afternoon of May 18, the eruption subsided, and by
early the next day it had essentially ceased. Mount St. Helens'
volcanic cone was completely blasted away and replaced by a
horseshoe-shaped crater--the mountain lost 1,700 feet from the
eruption. The volcano produced five smaller explosive eruptions during
the summer and fall of 1980 and remains active today. In 1982,
Congress made Mount St. Helens a protected research area.
Mount St. Helens became active again in 2004. On March 8, 2005, a
36,000-foot plume of steam and ash was expelled from the mountain,
accompanied by a minor earthquake. Though a new dome has been growing
steadily near the top of the peak and small earthquakes are frequent,
scientists do not expect a repeat of the 1980 catastrophe anytime
soon.
history.com/tdih.do
1860 : Lincoln nominated for presidency
history.com/tdih.do?action=tdihArticleCategory&id=5011
1896 : Supreme Court rules in Plessy v. Ferguson
history.com/tdih.do?action=tdihArticleCategory&id=5012
1974 : India joins the nuclear club
history.com/tdih.do?action=tdihArticleCategory&id=5013
##########################################
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