Mt St Helens Volcano Flashcards
Where is Mt St Helens?
Washington state, North America, south of Seattle
What are the two plates involved?
Juan de Fuca, North American
Which range of mountains in Mt St Helens in?
The Cascade mountain range
Which plate was subducting under the other?
Juan de Fuca is subducting
When was the volcanic activity taking place?
20th March 1980- 18th May 1980
What were the causes of the eruption?
A bulge growing on the north side as magma was rising through cracks and building up pressure at this point. An earthquake with a magnitude of 5.1 caused half of the mountain to slip and burst the bulge
What were some primary effects?
Pyroclastic flows
Everything was killed and destroyed within a 17mile radius of the volcano
Deaths: Dave Johnson, scientist, 30; and Harry Trueman, local resident that refused to leave, 84
What were secondary effects of the eruption?
Rivers and lakes temperature rose to 30°c because of mudflow
Local students had an early vacation due to road and access complications
Scientists managed to learn more about volcanoes
Soil became fertile from the ash
Tourist numbers increased dramatically
What were some social effects?
Job losses due to destruction of salmon farms
61 lives lost
200 cabins and homes destroyed so some people were left temporarily homeless
What were some environmental effects?
Landscape of 250km2 left devoid of trees
Lahars blocked and diverted River Toutle
2million birds and animals killed, taking years to repopulate
What are some economic effects?
Total cost of damage totalled to $1Billion
Agriculture trad was devastated
Ash removal from the state of Washington cost $2.2million
What were the short term responses?
Helicopters mobilised and airlifting people from the blast zone
Peope and tourists evacuated to a safe zone of 25 miles
Extra masks provided to cut risk of respiratory problems for workers and residence
What were the long term responses?
Roads and bridges were rebuilt crossing the Toutle and Green Rivers
Forests to the north of St Helens were replanted
Tourist industry rebranded and invested
What happened three days after the eruption?
The volcanic plume reached the east coast of the USA
