April 1 - Several plumes from explosions
reached altitudes of 20,000 feet. Ashfall was reported south of the mountain in
Cougar and as far away as the outskirts of Vancouver. Some observers claimed these
were the strongest explosions to date.
Ongoing explosive activity has caused the two craters to merge into one single
crater over 600 feet across. A block of the summit bounded by two crack systems
has sunk at least 200 feet. The settling has caused noticeable outward displacement,
or bulging, of the rocks and ice north of the crater. Two earthquakes of magnitude
4.7 occurred, as well as the first weak harmonic tremor.
The occurrence of larger earthquakes accompanied by harmonic tremor, more vigorous
explosions, and presence of sulfur dioxide led scientists to suggest that there
is an increased possibility of an eruption involving magma.
Attempts to obtain aerial photographs of the mountain were unsuccessful due
to poor weather. Scientists would like photos to compare with similar ones taken
in 1979 to help determine the physical changes that have occurred.
Cowlitz and Skamania County officials decided to ask the Washington National
Guard for assistance. The two counties have been maintaining six roadblocks around
the clock since March 27. They estimate that because of the extensive network
of logging roads, they would need as many as 29 roadblocks and 175 officers to
completely block off access.
Nolan Lewis, Director of Cowlitz County Emergency Services, was quoted in the
Tacoma News Tribune, "I just can't fathom it, people are swarming in from all
over, putting their lives in danger ... Sunday when the weather was clear, the
road up to the mountain looked like downtown Seattle at rush hour."
Federal Aviation Administration (FAA) officials transferred control of air
traffic operations around Mount St. Helens to their Seattle center. In a Vancouver
Columbian article, an FAA spokesman said that an estimated 100 planes were in
the controlled area at times. Aircraft have maintained radio silence and illegally
entered the restricted area from all directions and altitudes.
According to a Longview Daily News article, one pilot reported, "It was like
a dog fight over the crater last Thursday (March 27) before the Forest Service
started its air control."
About 300 loggers returned to work in areas northwest of the volcano.
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Large cracks crossing the summit bounded a wedge of rock and ice that included
the crater. This block, or graben, had sunk at least 200 feet by April
1. USGS photo courtesy of Richard Waitt.
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