3.2.2 Impacts of and responses to Volcanic Hazards

Question 1

Primary impacts

Answer 1

Primary impacts are a direct result of the eruption.

• For example, people can be killed by pyroclastic flows.

Question 2

Secondary impacts

Answer 2

Secondary impacts occur as a result of the primary impacts.

• For example, pyroclastic flows can melt glaciers and cause flooding.

Question 3

Social impacts of volcanic hazards

Answer 3

• People are killed, and buildings and infrastructure are destroyed by pyroclastic flows and fallout.
• Pyroclastic flows and lava flows can start fires that damage buildings.
• Mudflows and flooding from ice melt can cause further damage and deaths.

Question 4

Economic impacts of volcanic hazards

Answer 4

• Eruptions can destroy businesses, and ash clouds can prevent aircraft flying and damage crops. This damages the economy of the region and the country.
• Damage to buildings and infrastructure can be very expensive to repair.
• Eruptions and the scenery they form can attract tourists, boosting the economy.

Question 5

Environmental impacts of volcanic hazards

Answer 5

• Ecosystems can be damaged or destroyed by flows and fallout of volcanic material.
• Acid rain can cause acidification of aquatic ecosystems, killing some plants and animals. It also damages the leaves of trees and removes nutrients from the soil, damaging forests.
• Volcanic gases contribute to the enhanced greenhouse effect and can add to global warming.
• Clouds of ash and volcanic debris can reduce the amount of sunlight reaching Earth, decreasing temperatures over large areas.

Question 6

Political impacts of volcanic hazards

Answer 6

• Damage to agricultural land can cause food shortages, leading to conflict and political unrest.
• Governments may have to spend money on repairing damage to buildings and roads, rather than schools or hospitals, so countries may not develop as rapidly.

Question 7

Hazard mitigation

Answer 7

Anything that is done to reduce the severity or impacts of a hazard. This can be done through short-term or long-term responses to the volcanic hazards.

Question 8

Short-term responses

Answer 8

Short-term responses normally occur immediately before, during or immediately after the hazard begins – they include things like evacuating people from areas at risk from an eruption and providing emergency food supplies.

Question 9

Long-term responses

Answer 9

Long-term responses are designed to reduce the impacts of future eruptions by managing the risks.

They fall into three main categories:
- Prevention
- Preparation
- Adaptation

Question 10

Prevention

Answer 10

• It’s not possible to prevent a volcanic eruption.
• However, it is sometimes possible to prevent eruptions posing a risk to people -e.g. authorities can prevent the land around volcanoes from being developed.

Question 11

Preparation

Answer 11

Preparedness is about what happens before an eruption to minimise risk or vulnerability. For example:

• Authorities can install monitoring systems to predict when an eruption might occur, and make plans for how they will evacuate people if there is an eruption.
• If an eruption is imminent, authorities can stop people from entering the area around the volcano.
• Individuals can make sure they are prepared, e.g. by finding out where their nearest emergency shelter is, or making an emergency kit containing a torch, medicine, dust masks etc.
• Communities can set up search and rescue teams or fire response units to tackle the impacts of an eruption.

Question 12

Adaptation

Answer 12

Adaptation is about how people change their behaviour or surroundings to minimise the risks and maximise the benefits of living near a volcano. For example:

• Buildings can be strengthened to reduce the change of collapse if a layer of ash lands on them.
• People can capitalise on the opportunities of living near the volcano, e.g. by farming (volcanic ash makes soil very fertile) or by working in the tourist industry.

Question 13

Strategies used to monitor volcanic hazards

Answer 13

• Tiltmeters: Tiltmeters are placed on the flanks of active volcanoes and measures changes in the slope angle. These are usually linked to changes in the shape and activity of magma.
• Sampling gases: Long term study of volcanoes. The easiest but most dangerous monitoring method as it involves simply placing a container directly into the gases, which can then be analysed.
• Monitoring tremors: Using seismometers to measure any earthquakes occurring near an eruption or volcano.
• Monitoring temperatures: By measuring temperature we can (sometimes) predict when an eruption may occur. Volcanoes become hotter when magma starts to rise through the main vent.
• Animal behaviour: Animals can indicate when the volcano is about to erupt. For example: Goats and Sheet on Mount Etna.

Question 14

Strategies used to mitigate against volcanic hazards

Answer 14

• Lava diversion channels: Lava can be diverted to avoid hitting certain areas. Some different types include:
  __Bombing__ – Dropping a bomb in lava channels to divert the flow. E.g. Hawaii’s big island
  __Blasting__ – Directing icy seawater onto the flow of lava. E.g. Vestmannaeyjar in Iceland
• Lava bomb shelters: A lava bomb is a mass of volcanic rock. A shelter can be used as a place to hide from these lava bombs.
• Evacuation: Having an efficient evacuation programme is very important at protecting lives.
• Education: By educating people (in schools and the wider community) about the dangers of volcanoes, we can encourage people to stay away from volcanoes when they erupt.
• Zoning: Areas can be classified in zones ranging from extreme risk to safe. Five zones:
  1) Extreme risk
  2) High risk
  3) Medium risk
  4) Low risk
  5) Safe