VOLCANIC HAZARDS

Volcanic hazards are defined as any potentially dangerous volcanic process that puts human life, livelihoods and/or infrastructure at risk of harm.

Numerous types of hazards may result from a volcanic eruption. The type and intensity of a given hazard will vary from volcano to volcano.

Hazards may also vary from eruption to eruption as well as across the sequence of a single eruption.

These hazards can have severe impacts on people, infrastructure, and the environment. Below is a list of common volcano hazards:

Primary Hazards (Directly Caused by Eruption)

Lava Flows

• Slow-moving streams of molten rock that destroy everything in their path.

Pyroclastic Flows

• Fast-moving currents of hot gas, ash, and volcanic debris that can travel down volcano slopes at high speeds.

Ashfall (Tephra)

• Fine volcanic ash and larger rock fragments ejected during an eruption, causing health hazards, crop damage, and infrastructure disruptions.

Volcanic Gas Emissions

• Release of gases such as carbon dioxide (CO₂), Sulphur dioxide (SO₂), hydrogen sulphide (H₂S), and water vapor, which can affect air quality and human health.

Volcanic Explosions

• Explosive eruptions that release energy, debris, and shockwaves, causing widespread damage.

Lahars (Volcanic Mudflows)

• Fast-moving mixtures of volcanic ash, debris, and water, typically triggered by heavy rainfall, melting ice, or the collapse of volcanic deposits.

Volcanic Bombs and Blocks

• Large fragments of rock ejected from a volcano during explosive eruptions, which can cause localized destruction.

Volcanic Lightning

• Electrical discharges caused by the interaction of ash particles in the volcanic plume.

Secondary Hazards (Triggered or Indirect Hazards)

Tsunamis

• Ocean waves generated by volcanic activity, often due to undersea eruptions, landslides, or caldera collapses.

Ground Deformation and Landslides

• Movement or collapse of volcanic slopes, potentially causing landslides that destroy settlements and infrastructure.

Acid Rain

• Rainfall made acidic by volcanic gases like SO₂ mixing with water in the atmosphere.

Climate Effects (Volcanic Winter)

• Large eruptions injecting ash and Sulphur aerosols into the atmosphere can cool the Earth by blocking sunlight.

Hydrothermal Explosions

• Sudden release of steam and hot water from beneath the surface, triggered by volcanic heat.

Famine and Food Insecurity

• Long-term impacts from ashfall and lava flows destroying farmland and disrupting food supplies.

Seismic Activity

• Earthquakes associated with volcanic activity that can damage infrastructure and induce landslides.

Tertiary Hazards (Long-Term Impacts)

Soil Contamination

• Deposition of ash and lava altering soil chemistry, affecting agriculture.

Health Impacts

• Respiratory issues, skin irritation, and long-term exposure to volcanic gases causing health complications.

Ecosystem Disruption

• Destruction of habitats and alteration of ecosystems due to volcanic materials and gases.

Loss of Livelihoods

• Economic and social impacts on communities reliant on agriculture, tourism, and natural resources.

Infrastructure Damage

• Long-term rebuilding costs due to destroyed roads, buildings, and utilities.