The silent build-up to a super-eruption

Photo of Lake Toba in Sumatra and its island created by the accumulation of magma in the volcano's magma reservoir. UNIGE - Geologists from the UNIGE and Peking University have developed a technique that makes it possible to estimate the maximum size of a future super-eruption of Toba volcano in Sumatra. It is estimated that about 5-10 volcanoes worldwide are capable of producing a super-eruption that could catastrophically affect global climate. One of these volcanoes hides below the waters of Lake Toba in Sumatra and has caused two super-eruptions in the last one million year. But when will the next one be? Will there be any warning signs? To answer these questions, an international team of geologists led from the University of Geneva , Switzerland, and Peking University, China, developed an analysis of the levels of uranium and lead in zircons - a mineral typically found in explosive volcanic eruptions - to determine how long it took the volcano to prepare for its super-eruptions. Unfortunately, these results, published in the journal Proceedings of the National Academy of Sciences ( PNAS ), refute the notion that unusual geological signs would herald an imminent super-eruption. Instead, the magma silently accumulated in the magma reservoir until these massive explosions occur.