Risk of supervolcano eruption big enough to 'affect the world' far greater than thought, say scientists

[link to www.independent.co.uk] analysis of the molten rock within the dormant supervolcano beneath Yellowstone National Park in the United States has revealed that an eruption is possible without any external trigger, scientists said.

Scientists previously believed many supervolcanic eruptions needed earthquakes to break open the Earth’s crust so magma could escape. But new research suggests that this can happen as a result of the build-up of pressure.

Supervolcanoes represent the second most globally cataclysmic event – next to an asteroid strike – and they have been responsible in the past for mass extinctions, long-term changes to the climate and shorter-term “volcanic winters” caused by volcanic ash cutting out the sunlight.

The last known supervolcanic eruption was believed to have occurred about 70,000 years ago at the site today of Lake Toba in Sumatra, Indonesia. It caused a volcanic winter that blocked out the sun for between six to eight years, and resulted in a period of global cooling lasting a thousand years.