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12 Cards in this Set
- Front
- Back
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What had happened in the last 100 years and what was the volcano located in?
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-Pre 1980, no eruption for 100 years
-Composite cone volcano on a destructive plate margin -Located in a national park and area around used for tourism, salmon fishing and agriculture. |
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What was happening just before the eruption?
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-1980- Scientists recorded 100s of tremors from from the mountain
-Attracted 100s of reporters and tourists but by May a large visible bulge appeared on Northern flank. |
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What triggered the eruption?
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1.) 8.32am- 18th May- eruption began with 5.1 magnitude earthquake which broke the bulge and created a large avalanche.
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What did an avalanche cause?
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2.) Avalanche released built up pressure from magnetic gases which created a northern lateral explosion.
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What happened to the top of the mountain?
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3.) Top of the mountain had gone and this allowed the eruption to rise 16 miles driven by a chain of explosions within the core, this continued for 9 hours.
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What was the damage between 9-19 miles from the volcano?
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-9 miles- how long the blast force and pyroclastic force incinerated everything
-9-17 miles- stripped trees of bark and flattened them -17-19 miles- heat burnt and killed trees. |
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What were the social impacts
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-56 people killed within the blast zone
-Lahars destroyed over 200 homes, 27 bridges, 185 miles of road and 15 miles of railway -Eruption did however increase tourism and fame |
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What were the environmental Impacts
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-Spirit lake was filed in by the landslide.
-250km cubed of forestry was destroyed -32 known species of mammals were there before, only 14 survived -250 km of river ecosystem was destroyed by lahars which killed all fish life. -7000 big game animals were killed. -Flood Risks increased as Toutle and Cowlitz rivers were choked with mud and debris. |
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What were the economic impacts
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-Logging camps were destroyed
-12% of crops in the area were damaged or destroyed -Short term economic losses in Washington State reached £800 million -Cleanup cost $250 million alone |
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What was the first Response
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-Exclusion zone set up in March
-2000 people were evacuated -Public opposition to exclusion zone so people tried to pass roadblocks and get closer |
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What was the immediate Response
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-National Guard helicopters rescued 130 people from blast zone over 2 weeks
-National guard issued water, food rations, medical supplies and 2 million gas masks -Ash cleared from towns such as Yakima after 3 days2 |
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What was the long term response?
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-Toutle, Cowlitz and Columbia rivers were dredged.
-10 million trees were replaced -Bridges were built to control lahar blockages -Volcano monitered constantly by USGS and plans to alert and prepare people beyond blast zone. |
