Volcanic Hazards

Question 1

The nature of volcanic hazards

Answer 1

5% are intraplate, 95% are associated with plate margins.

The nature depends on the type of eruption, most occur on destructive and constructive plate margins.

Question 2

Volcanic eruptions at constructive margins

Answer 2

Basaltic lava forms here.
Eruptions are frequent and last a long time.
They aren’t violent.
Lava is hot and low in viscosity, meaning it flows easily and quickly and can cover large distances.
e.g. Sutsey, Iceland.

Question 3

Volcanic eruptions at destructive margins

Answer 3

Andesitic and rhyolitic lava forms here.
Eruptions are short lived and not very frequent but are violent.
Lava is cooler and more viscous, meaning it flows less easily.

Question 4

Hotspots

Answer 4

Tend to have basaltic lava and gentle slopes e.g. Hawaii.

Question 5

Frequency

Answer 5

Depends of the type of volcano
e.g. Kilauea, Hawaii - active shield volcano that has erupted continuously like 1983.
whereas Yellow Stone Caldera has erupted just 3 times in the last 2.1 million years.

Question 6

Social impacts of volcanic eruptions

Answer 6

People killed, buildings and infrastructure destroyed.
Pyroclastic flows can start fires that damage buildings.
Mudflows and flooding can cause further damage and death.

Question 7

Economic impacts of volcanic eruptions

Answer 7

Businesses destroyed
Aircraft is prevented from flying
Crops damaged
Damage to buildings and infrastructure is expensive to repair.
The scenery eruptions form can attract tourists.

Question 8

Environmental impacts of volcanic eruptions

Answer 8

Ecosystems are damaged.
Acid rain can cause acidification of eco systems - it damages leaves on trees and removes nutrience from soil.
Volcanic gases = enhanced greenhouse effect
Ash clouds can block out sunlight, decreasing the earth’s temperature.

Question 9

Political impacts of volcanic eruptions

Answer 9

Food shortages lead to conflict and political unrest.

Countries will not develop as rapidly as they have to spend their money on repairing damage.

Question 10

Monserrat key facts

Answer 10

The Soufriere hills
Erupted in 1997 - a series of large eruptions between June and September- the largest of which produced 4-5million cm^3 of material in a 20 minute period.
It is a small island in the carribean sea
Plymouth is its capital city.
The volcano was formed on a destructive boundary where the North American plate is subducted by the Carribean plate.

Question 11

Social impacts - Montserrat

Answer 11

19 died and 7 injured
Plymouth destroyed- including government offices, police headquarters, and petrol stations.
Airport destroyed
1/2 of the island evacuated

Question 12

Economic impacts - Montserrat

Answer 12

Total loss of value of people’s homes and investments was 1 billion
Tourist attractions such a beaches were destroyed
(however tourists now pay to see the volcano)
20 villages and 2/3 of homes lost

Question 13

Environmental impacts - Montserrat

Answer 13

Forests, beautiful scenery, vegetation and farmland were destroyed.
Volcanic ash improved soil fertility.
Plymouth was buried under 12m of mud and ash.

Question 14

Mitigation

Answer 14

Anything that can be done to reduce the severity of a hazard

Question 15

Short term responses to volcanic eruptions

Answer 15

Evacuation + providing emergency food supplies

Question 16

Prevention

Answer 16

Volcanic eruptions cannot be prevented, however it is possible to prevent the risk caused to people by preventing the land around volcanoes from being built on.

Question 17

Preparedness

Answer 17

Monitoring systems may be installed by authorities to predict and eruption so evacuation can take place.
If an eruption is immanent they can stop people from entering the areas around the volcano.
Emergency shelters and emergency kits such as torches, medicine and dust masks can be put together by individuals to prepare themselves.
Communities can train search and recue teams or fire response units.

Question 18

Adaptation

Answer 18

Buildings can be strengthened to reduce the chance of them collapsing if a layer of ash falls on them.
People can capitalise on the opportunities of living near a volcano (by working in the farming or tourist industry).

Question 19

Short term reponses to Montserrat

Answer 19

People were evacuated to the North
Shelters, temporary roads and electricity supplies were built.
£17 million of emergency aid was provided by the UK.
Search and rescue teams provided.

Question 20

Long term responses to Montserrat

Answer 20

The volcano is still intermittently active, so there is an exclusion zone on the south of the island.
£41 million of long term aid was provided by the UK which has been used to build new docks, an airport and houses.
The Montserrat Volcano Observatory was set up to predict future eruptions.
Many residents are still living in other Caribbean Islands, the UK and New York.