Volcano Case Studies

Question 1

What kind of volcano is Mount St Helens?

Answer 1

Composite

Question 2

How was Mount St. Helens formed?

Answer 2

Subduction between Juan de Fuca and North American plates

Question 3

When was the initial 4.2 magnitude EQ on Mount St. Helens?

Answer 3

20th March

Question 4

Mount St. Helens 18th may…

Answer 4

5.1 EQ cause north side of volcano to collapse leading to Avalanche which created lahars. Ash eruption for 9 hours

Question 5

What did the Mount St. Helens eruption create?

Answer 5

1-2 mile wide, 800m deep crater

Question 6

How many died in Mount St. Helens?

Answer 6

57

Question 7

Effect Mount St. Helens had on animals…

Answer 7

7000 game animals killed and 12milkion fish from hatcheries killed. 20,000 acres of forest also destroyed causing loss of habitat

Question 8

How did Mount St. Helens disrupt travel?

Answer 8

185 miles of road, 15 miles of railway destroyed and 2 day airport closure so 1000s flights cancelled

Question 9

What year was Mount St. Helens eruption?

Answer 9

1980

Question 10

Secondary impacts of Mount St. Helens?

Answer 10

Lahars covered large area, ash blocked rivers causing flooding

Question 11

Economic impacts of Mount St. Helens

Answer 11

Agricultural crops destroyed, ash removal cost $2.2M & total cost $1.1B

Question 12

Immediate responses warning of eruption

Answer 12

Evacuation of those in blast zone and then evacuation of those in exclusion zone

Question 13

What did USGS scientists use to predict it would erupt soon?

Answer 13

Seismometers, ground surface measurements, Arian infrared surveys and surface temperature measurements

Question 14

What date did Nevado del Ruiz erupt?

Answer 14

13th november 1985

Question 15

What kind of volcano is Nevado del Ruiz?

Answer 15

Composite

Question 16

How did Nevado del Ruiz form?

Answer 16

Due to subduction of Nazca plate below South American plate

Question 17

What were the warning signs before the main eruption of NdR?

Answer 17

1984 funerole activity and sulphur deposits on summit. 11/09/95 steam erupted

Question 18

How were lahars, up to 50m wide, on NdR created?

Answer 18

Pyro clastic flow melted snow and glaciers

Question 19

Main economic impacts of NdR?

Answer 19

3,490 hectares of agricultural land lost. Cost Colombian government $7.7B

Question 20

Social impacts of NdR

Answer 20

Roads&communications, 2 hospitals, 50 schools & 58 industrial plants destroyed

Question 21

What did the large lahars do?

Answer 21

Kill 150,000 animals and swept through Armero killing 23,000 people & injuring 5,000

Question 22

Short term responses to NdR

Answer 22

80,000 doses of tetanus & typhoid vaccines

5-8 helicopters from Colombian military(lahars made rescue on land hard)

Question 23

Why did NdR receive less aid than it should have?

Answer 23

Mexico City EQ two weeks before so lots of aid/resources already sent there

Question 24

Long term responses to NdR…

Answer 24

1986 public education campaign on volcano hazards. Red cross civil aged flyers on hazards&evacuations.
Colombia made plans for warning&evacuating. Evacuation route markers painted on buildings

Question 25

What was done to prepare for NdR eruption?

Answer 25

Little. Hazard warning maps but no key, some errors and poorly distributed