Mount St. Helens - case study

Causes, Effects, Immediate responses and Long Term responses

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  • Mount St. Helens - case study
    • Causes
      • DESTRUCTIVE plate boundary
        • The Juan de Fuca plate subducted under the North America plate
      • Bulge in side of mountain lava build up
        • Blew its top causing a  LATERAL blast
      • 5.1 on RICHTER SCALE causes BIGGEST LANDSLIDE EVER
      • Earthquakes and steam filled with ash- signs of an eruption
    • Effects
      • EVERYTHING 27km NORTH OF THE CRATER WIPED OUT
        • 8km exclusion zone
      • 57 people died
        • 250 homes, 47 bridges, 15 miles of railway and 185 miles of road destroyed
      • Biggest Landslide ever recorded
      • Nearby cities become dark because of ash cloud
        • Roads and Air con clogged by ash
        • 15cm of ash fell
      • Water produced from melting snow and ice created mud flows
        • This choked the river and killed all fish and water life
      • Every tree within 30 km of the volcano was uprooted and flattened
      • The Spirit Lake was filled with mud killing over 12 million Salmon
      • The ash that had  eventually fallen made the soil more fertile (positive impact)
    • Immediate Responses
      • Helicopters search and rescue
        • 200 people rescued
      • Shelter provided for those who had lost homes and stranded tourists
      • Ash cleared from roads
      • Medical supplies given to injured
    • Long Term Responses
      • Building and bridges need rebuilding
      • Drainage checked so that it wasn't blocked by debris and cause floods
      • Forest replanted
      • Roads rebuilt
      • Tourist industry rebuilt
      • Millions of trees replanted and fallen tree removed

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