What is a volcano?

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.

Source: World Health Organisation

Types of volcanic eruptions

Volcanic eruptions can be explosive, sending ash, gas and lava high up into the atmosphere, or the magma can form lava flows, known as effusive eruptions. Whether an eruption is explosive or effusive largely depends upon the amount of gas in the magma.

Source: British Geographical Survey