MT St HELENS 18th may 1980

  • Created by: 244466666
  • Created on: 12-03-18 11:44

MT St HELENS 18th may 1980


  • Jaun de Fuca plate subduct under North American Plate
  • destructive plate boundary in Washington, north west america
  • bulge on North Face of volcano appeared- became unstable and collapsed as an avalanche
  • avalanche casued ice to melt- mud flows- choked all rivers, killing all fish
  • minor earthq. before
  • tiltmeters used to monitor size/ shape of bulge + volcano


  • SOCIAL -63 killed- mainly by poisionous gasses
  • damage to infrastructure
  • 250 homes destroyed
  • 15 miles railways/ 185 miles roads destroyed
  • ENVIRONMENTAL-lahars (mudflows of ash and water) destroyed forrests/ logging camps- covered extensive area surrounding volcano
  • 15cm ash fell
  • popular fishing sites destrouyed, due to river blockages casued by ash- caused flooding, destroying farmland (crops/livestock)
  • every animal/ plant 25km north of volcano destroyed- 7000 animals dies - every tree within 30km was flattened
  • ECONOMICAL - air clogged up car engines/ machinery- damage totelled 100 million
  • loss in tourism
  • timber industry was damaged due to fallen trees

Overall summary

RESPONSES- (SHORT) rescuing stranded people, shelter,medical, aid operation rescued under 200 ppl- landscape changed so much, maps were hard to use- slowed down rescue efforts (LONG) million tonnes of ash removed from roads, build, airports - cost over $1 million. Trees replanted. compensation to farmers who lost land due to ash. river/ channel dredged. money given to rebuild houses as 200 destroyed. money given to redevelop salmon hatcheries as millions baby salmon destroyed 


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