hazards (volcanoes- Mount st helens) Flashcards
where was Mount st helens?
USA- Washington
cascade mountains
when?
18 may 80
what is plate boundary of the cascade mountains?
destructive
what plates?
Juan de fuca plate under N.American plate
what type of volcano is Mt st helens?
composite
when did people start seeing signs of a volcano?
march 80
what were the signs that there was going to a be a volcano?
- small EQ
- buldge
- ash/steam
what was the magnitude of the volcano?
5.1
what were the 5 things released from the volcano?
shral
- rock
- ash
- hot gases
- steam
- lava
what were the 3 results of the eruption?
- pyroclastic flows
- lahars
- flood
how far was the blast zone?
600km^2 fan shaped area N of volcano
what distance from the volcano was all of the vegetation and buildings destroyed?
30km
how much ash was released from the volcano?
-540mil tonnes of ash over area 54,00km^2
name 4 environmental impacts?
- 240km^2 forest destroyed
- 7000 animals, 12 mil salmon killed
- sediment ^ water level by 60m
- water quality reduced
name 4 economic impacts?
- total cost $1.1 bil
- 200 homes destroyed
- airports closed 1000 flights cancelled
- $2.2 mil to clear ash in yakima
