Volcanic Hazards Case Study

Question 1

When and where did the Montserrat eruption occur?

Answer 1

Soufriere Hills Volcano
June 1997

Question 2

Outline features of the Montserrat volcano

Answer 2

Composite volcano
Above destructive plate margin NA plate subducts under Caribbean plate

Question 3

What happened before the main eruption of Montserrat?

Answer 3

1995 - small eruptions, lahars & earthquakes

1997 - small earthquakes & pyroclastic flows

Question 4

Outline the main eruption of Montserrat

Answer 4

4-5 mil m^3 material released in 20min
Pyroclastic - 50m within airport - 5.5km from volcano
Large ash cloud

Question 5

Outline the secondary eruptions of the Montserrat eruption

Answer 5

Eruptions over next months - airport destroyed by pyroclastic flows September 1997

Question 6

Outline the economic impacts of the Montserrat eruption

Answer 6

1. Total value loss = £1bn
2. > 20 villages destroyed by pyroclastic flows
3. Tourism 1st disrupted but now increased due to volcano
4. Schools, hospitals, airport, port destroyed

Question 7

Outline the social impacts of the Montserrat eruption

Answer 7

1. 19 dead 7 injured
2. Hundreds lost homes
3. Population decline - 8000/12000 left since 1995
   4000 came to UK

Question 8

Outline the environmental impacts of the Montserrat eruption

Answer 8

1. Large areas covered with volcanic mats (e.g Plymouth 12m mud & ash buried)
2. Veg & farmland destroyed
3. Volcanic ash improved soil fertility

Question 9

Outline the eruption in Montserrat that occurred years later

Answer 9

Feb 2010 - explosive
Vulcanian eruption 15km column ash into the air

Question 10

Outline 3 short-term responses for the Montserrat eruption

Answer 10

1. Montserrat Volcano Observatory made in 1995 predicted 1997
2. NGOs (e.g Red Cross) provided temporary schools, medical aid & food
3. £17mil in UK paid aid for temporary buildings

Question 11

Outline 3 long-term responses for the Montserrat eruption

Answer 11

1. British citizenship granted in 2002
2. Warning sirens tested daily at 12.00 PM
3. UK finance aid >£420 mil since 1995

Question 12

Outline why the impacts for the Montserrat eruption were more severe than normal (3 reasons)

Answer 12

Little management B4
1. Scientists studied 1980 but ignored
2. No disaster management plan so responses slow
3. 1990s key infrastructure built in areas of risk

Question 13

Outline the Mt St Helens eruption (place & date)

Answer 13

Washington (USA), Mt St Helens
May 1980

Question 14

Outline the features of Mt St Helens

Answer 14

Composite volcano
Above a destructive plate margin - Juan de Fuca plate subducted under NA plate

Question 15

Outline the signs that appeared B4 the Mt St Helens eruption

Answer 15

March 1980 - small earthquakes, bulge on the volcano’s side, and releasing ash/steam

Question 16

Outline the main eruption of Mt St Helens

Answer 16

Magnitude 5.1 earthquake
Eruption of volcanic material (rocks, gas, ash & lava)
Covered 600 km^2 fan-shaped area - veg & buildings destroyed up to 30km away
Shortly after - 2nd eruption 540mil tonnes ash deposited over 57000km^2

Question 17

Outline 3 economic impacts of the Mt St Helens eruption

Answer 17

1. Total cost $1.1 bn
2. 27 bridges, 24km railways & 300km roads destroyed
3. 200 homes & cabins destroyed

Question 18

Outline 3 social impacts of the Mt St Helens eruption

Answer 18

1. 57 killed (inhaling volcanic ash)
2. Unemployment X10 but returned after clean-up
3. Hundreds lost homes

Question 19

Outline 3 environmental impacts of the Mt St Helens eruption

Answer 19

1. Almost 240km^2 forest destroyed
2. 7000 large animals (bears, deers, etc), thousands of birds, and 12mil young salmon killed
3. Sediment dumped in Spirit Lake - raised lake bottom >90m & water level >60m

Question 20

Who coordinated the emergency responses to the Mt St Helens eruption?

Answer 20

FEMA (Federal Emergency Management Agency) - involved both national organisations & local services

Question 21

Outline 6 responses to the Mt St Helens eruption

Answer 21

1. Face masks - no ash inhalation
2. Emergency shelters
3. Ash clean-up - 900,000 tonnes removed
4. Shipping channels had sediment cleared
5. 45,500 acres land replanted - 18.4 mil trees
6. Domestic water supplies

Question 22

Outline how good management meant evacuation was efficient during the Mt St Helens eruption

Answer 22

March earthquakes - United States Geological Survey monitoring - volcanic & seismic activity reports daily
USGS issued warnings about hazardous areas
March - 2000 people evacuated & volcano restricted
Still couldn’t predict eruption accurately