Mt St Helens

Question 1

When-2, Where-2, Why-2

Answer 1

• 18th May 1990, earthquake 5.1, massive eruption of rocks, gas, ash, lava
• March 1980 ther were signs- small earthquake and bulge, ash and steam released
• Washington, USA, Cascade mountains
• Covered 600km^2
• Above destructive margin, Juan de fuca under NA plate
• Composite volcano

Question 2

Economic Impacts-7

Answer 2

• $1.1 bil lost
• 200 homes and cabins destroyed
• Airports temporarily closed, 1000 flights cancelled
• $2.2 mil to clear ash in Yakima\
• 27 bridges, 24km railway, 300km roads destroyed
• river traffic + shipping disrupted, 31 ships stranded
• Timber industry affected by destruction of forest

Question 3

Social Impacts-5

Answer 3

• 57 killed
• hundreds lost homes
• unemployment rose x 10
• social and recreational sites + facilities destroyed
• emotional stress

Question 4

Environmental Impacts-4

Answer 4

• 240km^2 forest destroyed
• 7000 big game animals dead, 12 million young salmon dead
• sediment dumped in spirit lake
• Water quality reduced

Question 5

Responses-6

Answer 5

• Face masks were distributed in some areas to protect against ash
• Emergency shelters set up
• Ash clean up operations were organised, around 900000 tones of ash was removed
• Shipping channels were cleared and some new ones were created
• 45500 acres of land was replanted and 18.4 million trees planted
• Domestic water supplies were monitored for contamination

Question 6

Management

Answer 6

• When earthquakes began in march, USGS started monitoring, seismic data, rate of bulge growth, ground temp, sulfur gas emissions
• USGS issued warnings to people living in risk areas an d told them where to go to
• March volcano access was restricted and 2000 were evacuated
• Despite monitoring the data on the day of eruption there were no changes, impossible to predict