VOLCANO - Mt St Helens

Question 1

When was the eruption?

Answer 1

May 18th 1980.

Question 2

Describe the events leading up to the eruption.

Answer 2

• Juan de Fuca (Oceanic) plate met the North American plate at a destructive plate boundary.
• Earthquake.
• Began to spew ash and steam.
• Bulge grew by 1.5m a day.
• 18th May 1980: magnitude 5 earthquake. This caused a nuée ardente, or a pyroclastic flow. Following this there was a landslide, which released internal pressure and ultimately caused the eruption. Famously exploded sideways.

Question 3

What were the human effects of the eruption?

Answer 3

• 61 died, mainly due to asphyxiation.
• Popular fishing sites destroyed. Farms were covered by ash, which reached areas 24km away from the site of eruption. Although this is primary, it had secondary effects - agriculture faced a decline in the long term.
• 200 houses were buried with ash desposits of up to 120km. This caused homelessness in the long term.
• 185 miles of highway covered with ash. In the long term, this caused traffic and communications problems. Because of this, short term problems were harder to solve because it was harder for the emergency servives to reach the disaster area. It also, in the long term, caused a reduction in working days, which was detrimental to the economy.
• Because of this combined short and long term impact on the economy, the eruption cost $1.1 billion.

Question 4

What were the environmental effects of the eruption?

Answer 4

• Everything up to 24km away was destroyed. This included trees. In the long term, this mass deforestation made animals lose their habitats.
• 7,000 game animals were killed.
• Popular fishing sites, with fish inside, were destroyed.
• Primary rivers such as the Columba river channel were blocked. This caused flooding. This flooding damaged trees even further.
• Ash hurled into the air caused pollution and raised temperatures.

Question 5

What were the solutions?

Answer 5

• Short term:
  
  • Survivors rescued.
  • Shelter
• Long term:
  
  • Volcano monitored constantly.
  • Bridges built with wider berth.
  • Compensation given to farmers.
  • National monument dedicated to eruption.

Question 6

Why live near Mt St Helens?

Answer 6

• Next to Cascades Mountain Range, with Spirit Lake at front. Beauty spot.
• There is a national monument dedicated to Mt St Helens = publicity.
• Feel safe because well-monitored.
• Local fishing spot.
• Researchers stay there to study the volcano.
• Inertia - local community could not bring themselves to leave traditional homes. Harry R. Truman is an example of this.