Earth, Brown 2015 C6

Assessing volcanic hazards and risks

How are volcanic hazard and risk related?

Risk = hazard, exposure, and vulnerability.

Why do volcanoes need probabilistic hazard models?

Because eruptions are uncertain and variable.

What are hazard maps based on?

Past eruptions and computer models.

What is a limitation of hazard maps?

Past eruptions may not predict future ones.

What is a “bullseye” hazard map?

Zones of decreasing hazard away from volcano.

How are hazard boundaries defined?

Probabilistically, not fixed lines.

What is tephra hazard known for?

Wide dispersal and major economic impacts.

What is aleatory uncertainty?

Natural randomness in eruptions.

What is epistemic uncertainty?

Lack of knowledge about volcano systems.

What does probabilistic forecasting show?

A range of outcomes with likelihoods.

What is vulnerability in volcanology?

Ability to cope with hazards.

What are types of vulnerability?

Physical, social, political, cultural.

What is exposure?

People and assets in hazard zones.

What is an event tree?

Diagram of eruption outcomes and probabilities.

Where are event trees used?

Volcanic emergency management (VDAP).

What is risk mathematically?

Hazard × exposure × vulnerability.

Which region has highest global exposure?

Pacific region (2bn people, 25% volcanoes).

Why is Tokyo at high volcanic risk?

High cumulative hazard exposure.

Why is Jakarta at high risk?

High population exposure.

What is Port Moresby’s main risk factor?

High vulnerability.

What is an F–N plot?

Probability vs number of fatalities.

What is the main modern approach to volcanic risk?

Probabilistic, model-based, interdisciplinary assessment.