Volcanic eruptions

A volcano is a vent in the Earth’s crust from which eruptions occur. There are about 1500 potentially active volcanoes worldwide. When volcanoes erupt they can spew hot, dangerous gases, ash, lava and rock that can cause disastrous loss of life and property, especially in heavily populated areas. Volcanic activities and wildfires affected 6.2 million people and caused nearly 2400 deaths between 1998-2017.

There are different types of volcanic eruptive events, including:

• pyroclastic explosions, with is fast-moving hot gas and volcanic matter
• hot ash releases
• lava flows
• gas emissions
• glowing avalanches, when gas and ashes release.

Volcanic eruptions can also cause secondary events, such as floods, landslides and mudslides, if there are accompanying rain, snow or melting ice. Hot ashes can also start wildfires.

Volcanic eruptions can impact climate change through emitting volcanic gases like sulfur dioxide, which causes global cooling, and volcanic carbon dioxide, which has the potential to promote global warming.

Volcanic eruptions can pose multiple health threats depending on the proximity of the volcano to the community and whether there was any warning.

Volcanic eruptions can cause:

• suffocation
• infectious diseases, such as conjunctivitis
• acute and chronic respiratory diseases from falling ash and breathing gases and fumes
• burns and traumatic injuries, such as lacerations from falling rock
• eye and skin irritations from acid rain.

Ash and chemicals from the eruption can also generate risk of food and water contamination, and compromise basic services, like water, transportation, communications and health services. Likewise, the accumulation of ash on roofs can cause damage or collapse of buildings, both immediately and after the event.

WHO works with Member States to build resilient and proactive health systems that can anticipate the needs and challenges during emergencies so that they are more likely to reduce risks and respond effectively when needed.

The magnitude of the physical and human costs from volcanoes can be reduced if adequate emergency prevention, preparedness, response and recovery measures are implemented in a sustainable and timely manner. This includes, ensuring early warning systems are in place, evaluating the population, and raises awareness about the risks of volcanic activities.

As the health cluster lead for global emergencies, WHO works with partners to respond to:

• ensure appropriate food supplementation; 
• restore primary care services, like immunization, child and maternal health, and mental health;
• assemble mobile health teams and outreach;
• conduct epidemic surveillance, early warning and response;
• call for emergency funding to support health action.