Mt. St. Helen's

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  • Created by: OctaviaL
  • Created on: 06-06-16 15:05
Where is Mt. St. Helen's?
Washington, USA
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When did the eruption happen?
18th May 1980.
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What plate margin created the volcano?
Destructive plate margin of Juan de Fuca and N. American plates.
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How high was the ashcloud? What atmospheric level did it reach?
12 miles high. Upper stratosphere.
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What pushed the ash cloud as far east as New York?
Easterly prevailing winds from Pacific.
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Which direction was the lateral blast?
Northerly.
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How much of the volcano's mass was displaced?
12%.
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What sort of volcano was Mt. St. Helen's?
Stratovolcano.
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What was significant about the landslide? How fast did it move?
Largest landslide in recorded history. 150mph.
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How fast did the pyroclastic flow move?
300mph.
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What style of eruption was it? What was the VEI?
Plinean eruption. VEI 5.
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How many homes were destroyed?
More than 200.
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How much road was destroyed?
Over 300km.
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How many people were killed? What from?
57 mainly from asphyxiation.
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What happened to unemployment?
It rose tenfold in the immediate region in the weeks following the eruption although it almost returned to normal once timber salvaging and ash clear-up operations started.
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How many homes could the wood destroyed have built?
150,000.
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What is the name of area that suffered a crippling and temporary blow to tourism?
Gifford Pinchot National Forest area.
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How much ash was spread? Over what area?
540 million tonnes over 57,000km^2.
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What meant a low yield of crops?
Low photosynthesis.
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Where is Yakima? How much did the ash clear up here cost?
135km away. $2.2m.
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What was the total cost to farmers from damage of crops and machinery?
£100m.
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What was the size of the blast zone?
600km^2, up to 30km away.
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How many big game animals died? What are three examples of these?
Nearly 7000. Deer, elk and bear.
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How far downstream did the avalance travel? What river? How many salmon were killed?
24km. River Toutle. 12m.
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How high up the opposite slope did the waves from spirit lake travel?
800ft.
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How much did sediment raise the bottom of Spirit Lake by?
Over 90m.
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When did the volcano start showing signs of an imminent eruption? What were these signs?
March. 4.2 EQ, steam venting, side of volcano bulged.
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What did USGS do to monitor the volcano?
Used tiltmeters to monitor changing size and shape, monitored ground temperature and sulphur dioxide gas emissions.
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What was issued daily?
Volcanic and seismic reports.
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What happened on the 17th?
Earthquake swarm quietened down.
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What triggered the eruption?
5.1 mag EQ.
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Why were 90% of those killed outside the exclusion zone?
Scientists unable to predict lateral blast.
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How many people were evacuated?
2000.
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What was the exclusion zone based on?
Past eruptions.
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What were on standby?
Emergency planes and helicopters.
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What did authorities do immediately?
Mobilised people and equipment quickly to help 198 people by rescuing those stranded, providing shelter, distributing facemasks and providing medical supplies.
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What slowed down rescue efforts?
The landscape had changed so much that maps were no longer accurate.
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How many tonnes of ash were removed from roads, buildings and airports?
900,000.
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How many acres of land wee replanted? How many trees?
45,500 acres, 18.4m trees.
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How much money was given to farmers in compensation?
$70m.
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What happened in 1982?
Mt.St. Helen's was declared a 'National Monument'. 445km^2 are now a protected and preserved area used for scientific study, education, recreation and tourism.
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What has been happening since the 14th March 2016?
Earthquakes swarms, over 130 of very low magnitude, largest 1.3. The rates are steadily increasing, this is known as recharge.
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Other cards in this set

Card 2

Front

When did the eruption happen?

Back

18th May 1980.

Card 3

Front

What plate margin created the volcano?

Back

Preview of the front of card 3

Card 4

Front

How high was the ashcloud? What atmospheric level did it reach?

Back

Preview of the front of card 4

Card 5

Front

What pushed the ash cloud as far east as New York?

Back

Preview of the front of card 5
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