hazards (volcanoes- Mount st helens) Flashcards Preview

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Flashcards in hazards (volcanoes- Mount st helens) Deck (19)
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1
Q

where was Mount st helens?

A

USA- Washington

cascade mountains

2
Q

when?

A

18 may 80

3
Q

what is plate boundary of the cascade mountains?

A

destructive

4
Q

what plates?

A

Juan de fuca plate under N.American plate

5
Q

what type of volcano is Mt st helens?

A

composite

6
Q

when did people start seeing signs of a volcano?

A

march 80

7
Q

what were the signs that there was going to a be a volcano?

A
  • small EQ
  • buldge
  • ash/steam
8
Q

what was the magnitude of the volcano?

A

5.1

9
Q

what were the 5 things released from the volcano?

shral

A
  • rock
  • ash
  • hot gases
  • steam
  • lava
10
Q

what were the 3 results of the eruption?

A
  • pyroclastic flows
  • lahars
  • flood
11
Q

how far was the blast zone?

A

600km^2 fan shaped area N of volcano

12
Q

what distance from the volcano was all of the vegetation and buildings destroyed?

A

30km

13
Q

how much ash was released from the volcano?

A

-540mil tonnes of ash over area 54,00km^2

14
Q

name 4 environmental impacts?

A
  • 240km^2 forest destroyed
  • 7000 animals, 12 mil salmon killed
  • sediment ^ water level by 60m
  • water quality reduced
15
Q

name 4 economic impacts?

A
  • total cost $1.1 bil
  • 200 homes destroyed
  • airports closed 1000 flights cancelled
  • $2.2 mil to clear ash in yakima
16
Q

name 4 social impacts?

A
  • 57 killed
  • hundred lost homes
  • unemployment ^
  • emotional destress
17
Q

name 4 responses?

A
  • co-ord by FEMA
  • 900,000 tonnes ash removed
  • emergency shelters
  • domestic water supply
18
Q

name 4 good management responses?

A
  • gathering seismic data
  • warning
  • evacuation of 2000 people
  • access to volcanoes restricted
19
Q

what did Mt St helens declare in 1982?

A

‘national monument’- 445km^2 now protected & preserved area