Mt St Helens Volcano (USA)

A case study on Mount St Helens in the USA.Useful for work on volcanos

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Mt St Helens, USA
Mt St Helens is one of five volcanoes in the Cascade ranges in Washington State, USA. Like the
others, it has been dominant for many years. In March 1980 there were signs of an impending
eruption, at first earthquakes occurred and then steam filled with ash exploded onto the pristine
white glacial summit of the mountain. Residents had been told to leave and visitors were not allowed
in 8km exclusion zone around the crater.
The expected, yet unpredictable eruption happened at 8:32am on the 18th May. An earthquake
measuring 5.1 on the Richter scale caused a landslide on the north-east side of the mountain. This was
the biggest landslide ever recorded and the sideways blast of pulverised rock, glacier ice and ash
wiped out all living things up to 27km north of the crater. In the outer `blow-down' zone, the trees
(some 500-year-old cedars) were uprooted and tossed around like matchsticks in the swirling
volcanic fallout.
The aftermath
The immediate responses involved mobilising helicopters to search and rescue those in the vicinity of
the catastrophic blast. It became clear to Vancouver that those caught in the path of the immediate
blast could not have survived. Tourists within the exclusion zone were caught up in the mudflows;
others in the lateral blast. Rescuing survivors was a priority, followed by emergency treatment at
nearby towns. The ash clogged air-conditioning systems and blocked roads with drifts a meter deep
in places, and stranded tourists had to be found shelter. The ash had to be moved to allow traffic to
flow, which was done within 3 days of eruption.
The ash that had been such a disaster initially would have a positive impact on the quality of soil by
increasing its fertility- one reason why, some people choose to live near volcanoes. The long-term
responses began to take effect. Brides and buildings needed rebuilding. The drainage in the area had
to be looked at to see that flooding would not occur as a result of all the debris. The forest in the
area to the north began to be replanted by the forest service following removal of fallen timber.
Roads had to be rebuilt and attempts to bring tourists back became a consideration.
There have also been natural changes occurring in the area, which continue today. Within 10 years of
the eruption, small traces of green had already appeared. Insects, birds and animals, including elk
have all returned as the area recovers.
Mt St Helens is a better known area today than it was before the 1980 eruption; the books at the
visitor centres bear signatures from all over the world. The tourist industry has recovered over a long
period of time. The area was designated a natural monument in 1982, which led to the spending of
$1.4 million to transform the area and allow access for 3 million visitors it receives each year.
Type-Destructive
Effects-People had to move & people died because they were not expecting the outcome
Response-Search helicopters & looking for survivors
Management-Rebuild things

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