Mt St Helens case study

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  • Created by: Mimipotte
  • Created on: 07-05-15 15:23

Mt St Helens case study

Causes

  • In march 1980  there were signs of an impending eruption as first earth quakes occured and then steam filled with ash exploded onto the summit of the mountain.
  • Residents were told to leave and visitors were not allowed within 8km of the crater.
  • The eruption happened at 8:32am on the 18th of May, an earthquake measuring 5.1 on the richter scale caused a landslide on the NE side of the mountain.
  • It was the biggest landslide ever recorded and it wiped out all life within a 27km radius and all trees in the 25km blow-out zone were destroyed.
  • 57 people died, it would have been more if it had been another day but as it was sunday no-one was working at the logging camps.

Effects

  • Primary effects: were 61 deaths most caused by gas from the blast waves, electricity supplies were and telephone lines were cut , and several logging camps were destroyed.
  • Secondary effects were: Ash which fell into the rivers and lakes raised the water temperature while mud choked channels. Combined effect was the death of all fish and the loss of 250km of slamon and trout rivers. Flood water washed away several roads and railway bridges and falling ash hindered car engines in three states. 12% of the total crops were ruined by settling dust.
  • Immediate responses: Helicopters searched for survivors but soon realised no-one within the 25km radius blast zone could ave survived.
  • Mid-term responses: the ash clogged air-con systems and blocked roads with drifts a metre deep. Tourists needed shelter and roads had to be cleared from ash - a shortage of masks resulted
  • Long term responses: Buildings and bridges were needed to be rebuilt and drainage systems were checked for blockages as a result of debris. The norhtern forest had to be replanted. Roads also had to be rebuilt. Animals and nature are returning to the areas as the ash in the explosian is good for soil.

Overall summary

The event led to a total death toll of 61 it consisted of the biggest landslide ever recorded, however the death toll wasn't too substantial the worst effects were those caused by the settling dust, however most of the aftermath was cleared by around two years. 

Comments

smolsneks12

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you spelt salmon wrong. its spelt  s a l m o n. not salmon. just saying

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