Supervolcanoes remain a catastrophic threat for thousands of years after erupting

PERTH, Australia — When a giant volcano — or a supervolcano — erupts, the devastation can affect the entire world for years or even decades. While scientists have thought that these volcanic explosions only take place once every several thousand years, a new study finds these geological timebombs remain dangerous for centuries after their massive eruptions.

Lead author and Curtin University associate professor Martin Danišík says a study of an ancient supervolcano in Indonesia has revealed that such volcanoes stay active and a potential threat for thousands of years following their super-eruptions. The findings are leading scientists to rethink how the world prepares for these world-changing natural disasters in the future.

The study finds supervolcanoes often erupt several times within a span of tens of thousands of years. However, researchers haven’t been sure about what happens in between those massive explosions.

“Gaining an understanding of those lengthy dormant periods will determine what we look for in young active supervolcanoes to help us predict future eruptions,” says Danišík, from Curtin’s John de Laeter Centre, in a media release.

“Super-eruptions are among the most catastrophic events in Earth’s history, venting tremendous amounts of magma almost instantaneously. They can impact global climate to the point of tipping the Earth into a ‘volcanic winter’, which is an abnormally cold period that may result in widespread famine and population disruption,” the researcher continues. “Learning how supervolcanoes work is important for understanding the future threat of an inevitable super-eruption, which happen about once every 17,000 years.”

Living under the constant fear of eruptions

Researchers examined the fate of magma coming from the Toba super-eruption 75,000 years ago. They used the minerals feldspar and zircon as a sort of time capsule for the volcanic rocks. These minerals contain independent “records” of the accumulation of gases like argon and helium over the years following a volcanic eruption.

“Using these geochronological data, statistical inference and thermal modelling, we showed that magma continued to ooze out within the caldera, or deep depression created by the eruption of magma, for 5,000 to 13,000 years after the super-eruption, and then the carapace of solidified left-over magma was pushed upward like a giant turtle shell,” Danišík explains.

“The findings challenged existing knowledge and studying of eruptions, which normally involves looking for liquid magma under a volcano to assess future hazard. We must now consider that eruptions can occur even if no liquid magma is found underneath a volcano – the concept of what is ‘eruptible’ needs to be re-evaluated.”

“While a super-eruption can be regionally and globally impactful and recovery may take decades or even centuries, our results show the hazard is not over with the super-eruption and the threat of further hazards exists for many thousands of years after,” the study author concludes.

The study appears in the journal Communications Earth & Environment.