Peruvian glacier split triggers deadly tsunami

Chunk of ice the size of four football pitches falls from Hualcan glacier into Andean lake, resulting in at least one death
A glacier in the Peruvian Andes
A glacier in the Peruvian Andes. Photograph: James Brunker/Alamy

The following correction was printed in the Guardian's Corrections and clarifications column, Friday 16 April 2010

Writing of the impact on surrounding areas in Peru when a huge piece of ice broke from a glacier and fell into a lake, we equated the 200m by 500m slab to four football fields. Based on allowable pitch dimensions in European football, that should have been more like 10, 15 or even 20-plus pitches in area

A massive ice block broke from a glacier and crashed into a lake in the Peruvian Andes, unleashing a 23-metre tsunami and sending muddy torrents through nearby towns, killing at least one person.

The chunk of ice, estimated at the size of four football pitches, detached from the Hualcan glacier near Carhuaz, about 200 miles north of the capital, Lima, on Sunday. It plunged into a lagoon known as lake 513, triggering a tsunami that breached 23 metre (75ft) high levees and damaged Carhuaz and other villages, according to authorities.

The Indeci civil defence institute said 50 homes and a water processing plant serving 60,000 residents were wrecked. Trout fishermen initially presumed dead survived, leaving one confirmed death.

Authorities evacuated mountain valley settlements fearing that the ice block, measuring 500 metres by 200 metres, could be followed by more ruptures as the glacier melts.

César Álvarez, governor of Ancash region, which includes the affected area, blamed climate change. "Because of global warming the glaciers are going to detach and fall on these overflowing lakes. This is what happened," he told Canal N.

Two people were injured when they saw the torrent of water, panicked in their car and crashed. The number of casualties could have been much greater had the lake level been higher when the ice block fell.

"This slide into the lake generated a tsunami wave, which breached the lake's levees, which are 23 metres high – meaning the wave was 23 metres high," said Patricio Vaderrama, an expert on glaciers at Peru's Institute of Mine Engineers.

It was the latest evidence that glaciers are vanishing from Peru, which has 70% of the world's tropical icefields. They have retreated by 22% since 1975, according to a World Bank report, and warmer temperatures are expected to erase them entirely within 20 years.

The same phenomenon is under way in neighbouring Bolivia, where the Chacaltaya glacier, 5,000 metres (17,400ft) up in the Andes, used to be the world's highest ski run. Predictions that it would survive until 2015 seem to be optimistic: according to recent pictures a few lumps of ice near the summit are all that remains.

The World Bank report warned that the disappearance of Andean ice sheets would threaten hydro-electric power and the water supplies of nearly 80 million people.