Eleven thousand years ago, about a third of the cone of the Planchón-Peteroa volcano in Chile collapsed, causing ten billion cubic metres of rock to slide down and cover an area of 370 square kilometres. According to Daniel Tormey, of ENTRIX, an environmental consultancy based in Los Angeles, previous studies have ruled out heavy rainfall as a cause of the landslide, so glacial melting must have been to blame.

Tormey’s research on the collapse of Planchón-Peteroa, chosen because altitude and latitude make it likely to feel the effects of climate change before others, points to the likelihood of similar collapses taking place on other glaciated volcanoes around the world as global warming intensifies. Glacial melting removes the glue that holds steep mountain slopes together, and Tormey fears that the resulting landslides have the potential to cause significant loss of life. ‘There are far more human settlements and activities near the slopes of glaciated active volcanoes today than there were 10,000 years ago, so the effects could be catastrophic,’ he said.

Non-glaciated volcanoes may also pose a significant risk if climate change increases rainfall, according to ongoing studies being carried out by Bill McGuire of University College London and Rachel Lowe of the University of Exeter. ‘We have found that 39 cities with populations greater than 100,000 are situated within 100 kilometres of a volcano that has collapsed in the past and which may, therefore, be capable of collapsing in the future,’ McGuire told New Scientist.

December 2010