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Mindmap von vina_56, aktualisiert more than 1 year ago
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Mount St. Helens - Case Study
- Monitoring & Predicting - save lives
- satellites - ash clouds, emissions etc.
- seismic activity - tilt meters & seismographs
- thermal changes
- volcanic gases - sulphur/chlorine ratio
- satellites - ash clouds, emissions etc.
- Destructive plate boundary - Juan de Fuca & North American
- plates move towards each other
- oceanic crust - forced under continental playe
- oceanic crust melts into magma
- magma rises - convection currents force magma up through cracks
- magma rises - convection currents force magma up through cracks
- oceanic crust melts into magma
- oceanic crust - forced under continental playe
- plates move towards each other
- Secondary Effects
- ash mixed with melted snow = landslides
- fallen trees - blocked streams - knocked bridges
- ash fall = roads closed
- no fishing - killed fishes
- ash mixed with melted snow = landslides
- Primary Effects
- pyroclastic flow - blasted sideways from volcano
- flattened trees
- nearly 7000 big game animals perished
- Spirit Lake = ash & rock
- Toutle River = heated to 30°C
- peak of volcano = blasted away - 390m shorter
- flattened trees
- pyroclastic flow - blasted sideways from volcano
- Location - North-West of USA - in Washington - in Cascades Mountains (Rockies)
- Immediate Responses
- EVACUATION - Governor of Wash. - small eruptions of gas & steam = signs in early 1980
- 2 million gas masks - President - ash breathing
- Helicopter mobilised - any survivors
- Ash cleared from roads - travelling - visibility
- FLIGHTS CANCELLED - ash in air
- EVACUATION - Governor of Wash. - small eruptions of gas & steam = signs in early 1980
- Long-Term Responses
- 10 million trees replanted
- area = national monument - 1982 - $1.4 million - access road & visitor centres (attracts 3 million a year)
- Roads & Bridges - along Toutle River = rebuilt - residents & tourists
- 10 million trees replanted
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