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23 Nov 09
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From December 7, 1989 to January 6, 1990, and from No
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Cascade Range, Mount St. Helens is a large eruptive cone consisting of lava
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St. Helens catastrophically erupted on May 18, 1980. After many months of
lead-up activity, including the growth of a huge bulge on the north part of the
mountain, a moderate earthquake caused the entire north flank of the mountain to
slide away in the largest landslide in recorded history -
The newly exposed hot and pressurized rock in the volcano responded by producing
the largest historic volcanic eruption in the 48 contiguous U.S. states.[30] (See
the Geology section for more detail.) -
U.S. President Jimmy Carter surveyed the
damage and said, "Someone said this area looked like a moonscape. But the moon
looks more like a golf course compared to what's up there."[32]
A film crew, led by Seattle filmmaker Otto Seiber, was dropped by helicopter on St. Helens on May 23
to document the destruction. Their compasses, however, spun in circles and they quickly
became lost. A second eruption occurred on May 25, but the crew survived and was
rescued two days later by National Guard helicopter pilots -
On March 20, 1980, Mount St. Helens experienced a magnitude
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On March 20, 1980, Mount St. Helens experienced a magnitude 4.2 earthquake
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The collapse of the northern flank of St. Helens mixed with ice, snow, and water
to create lahars (volcanic mudflows). The
lahars flowed many miles down the Toutle and Cowlitz Rivers, destroying bridges
and lumber camps. A total of 3,900,000 cubic yards
(3,000,000 m3) of material was transported 17 miles
(27 km) south into the Columbia River by the mudflows.[43] -
For more than nine hours, a vigorous plume of ash erupted, eventually reaching
12 to 16 miles (20 to 27 km) above sea level.[44]
The plume moved eastward at an average speed of 60 miles per hour
(100 km/h) with ash reaching Idaho by
noon. Ashes from the eruption were found collecting on top of cars and roofs
next morning, as far as the city of Edmonton in Alberta, Canada -
From December 7, 1989 to January 6, 1990, and from No
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nd from
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14 Jan 08
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USGS Mount St. Helens
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map #26
USGS
Mount St.
Helens
Type
#21
Active
stratovolcano
Volcanic
arc
/
belt
Cascade
Volcanic Arc
Age of
rock
< #20
40,000
yrs
Last
eruption
#19
2004–2008
(ongoing)
First
ascent
#18
1853
by
Thomas
J.
Dryer
Easiest
route
#17
Hike via
south
slope of
volcano (closest area near eruption
site)
#1
Mount
St.
Helens
is an
active
stratovolcano
located
in
Skamania
County
,
Washington
, in
the
Pacific
Northwest
region
of
the
United
States
.
#2
It is 96
miles
(154
km)
south
of
Seattle
and 53
miles
(85
km)
northeast
of
Portland,
Oregon
.
#12
Mount
St.
Helens takes
its
English
name
from
the
British
diplomat
Lord St
Helens
,
a
friend
of
explorer
George
Vancouver
who made
a
survey of the
area
in the
late
18th
century.
#3
The mountain
is
located in
the
Cascade
Range
and is part
of
the
Cascade
Volcanic
Arc
, a segment
of
the
Pacific Ring
of
Fire
that
includes
over
160
active
volcanoes
.
#10
This volcano
is
well known for
its
ash
explosions
and
pyroclastic
flows
.
#4
Mount
St.
Helens is most
famous for
its
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field,
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