Case Study - Volcano MEDC - Mt. St Helens

Mt. St Helens

• Mountain rumbling for 2 months, 5 mile exclusion zone around the volcano.
• At 8:32am on May 18th 1980, rising magma a mile below the surface caused a landslide on the northern side of the volcano - which was massive, the largest recorded in history.
• 8000 million tons of rock rushed down the mountain --> triggered simultaneous blast of steam, pumise + ash, with a temperature of 600 degrees to the north at 670mph.

This unique lateral explosion caused:

• No trees left standing within 6 miles of the blast
• A cloud of ash 12 miles high
• Generated heat that melted glaciers in the area
  
  • This produced floodwaters 60 feet high which travelled at up to 100 mph. Brought down many trees.
    
  • The force of it swept away bridges up to 40 miles away.

• After the eruption, the mountain had lost approx. 1300 feet from its summit.
• 540 million cubic metres of ash had been thrown into the atmosphere. (At times, this was sufficient to turn day into night 50 miles away!!)
• By the end of the eruption, Mt. St Helens had claimed the lives of 57 people.