Case study: Yellowstone

Photograph of a hydrothermal feature at Yellowstone

A hydrothermal feature at Yellowstone

Yellowstone is one example of a supervolcano. Three huge eruptions have happened in the last 3 million years.

The last eruption was 630,000 years ago, and was 1,000 times bigger than the Mount St Helens eruption in 1980.

The large volume of material from the last Yellowstone eruption caused the ground to collapse, creating a depression called a caldera. The caldera is 55 km by 80 km wide.

The next eruption is predicted to have catastrophic worldwide effects.

The supervolcano at Yellowstone is formed because of a volcanic hotspot.

Every year millions of visitors come to see the related features, such as geysers and hot springs. Old Faithful is one example of a geyser.

Potential global impact of a supervolcano

If a supervolcano was to erupt there would be a global catastrophe.

It would kill around 100,000 people instantly and make most of North America uninhabitable as huge amounts of ash and dust would be thrown into the atmosphere.

It would spark climate change that might trigger a mini-ice age due to the amount of sulphur dioxide thrown into the atmosphere and reflecting solar radiation.

Potential impacts on peoplePotential impacts on the environment
Death and destruction - Over 100,000 people will be killed instantly due to the blast and pyroclastic event.Ejecta - a supervolcano will eject at least 1,000km3 of material (compared to 1km3 of a normal volcano). This could include a 25 mile high ash cloud.
Ash clouds would migrate across the globe (reaching the UK in 5 days), blanketing soil, clogging machinery, causing respiratory and health problems for people. Lahars (a destructive volcanic landslide or mudflow) would devastate whole communities.Ash - The ash thrown into the upper atmosphere will circulate around the globe and could cause a ‘dark summer’ – where no sunlight gets through for at least one year. 1,000 miles away, the layer of ash deposited on the ground will be over 3 metres thick. Some of this will cause massive lahar flows. Global temperatures could drop by 3 – 5 degrees and remain low for many years.
Food supply - Crops and food supplies would suffer hugely and prices would increase dramatically. Global famine and mass starvation would be inevitable.Pyroclastic event – Everything within a 100 mile radius (at least) of the eruption will be destroyed.
Changing a way of life – Homes would be destroyed; air, road and rail travel and transport would grind to a halt, water supplies would be contaminated – life as we know it would change radically and survival would become increasingly difficult.Ecosystem destruction - Whole ecosystems would be destroyed. Crops would be destroyed due to ash fall and animals would die due to respiratory problems and starvation.
Long term survival – If a global ice age was triggered due to the supervolcanic eruption, plants and animals would die quickly.
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