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Avalanches

Volcanic avalanche

Mount Taranaki, New Zealand: collapse of slopes 25,000 years ago carried debris 30 kilometers away

SCHWEDE66/WIKIMEDIA COMMONSMount Taranaki, New Zealand: collapse of slopes 25,000 years ago carried debris 30 kilometers awaySCHWEDE66/WIKIMEDIA COMMONS

A large volcano is dangerous for reasons other than the lava expelled. The collapse of the steepest slopes, due to instabilities in the areas that support the mouth of the volcano during an eruption, can cause avalanches of debris capable of altering the surrounding landscape in a matter of minutes. A team of geologists from the Autonomous University of Mexico and Massey University (New Zealand) published an article describing details of one of the largest events of this type, which occurred 25,000 years ago: the partial collapse of the walls that lined the Taranaki volcano, also called Mount Egmont, located on the west side of New Zealand’s North Island. This collapse of sections of the slopes of the volcano—still active today (the last eruption was in 1854) and whose summit reaches an altitude of 2,518 meters—spewed blocks of sediment chaotically, some landing 30 km from the Taranaki volcano (Geological Society of America Bulletin, June 30, 2014). The avalanche of material probably occurred around the time of the Last Glacial Maximum, the most extreme period of the most recent Ice Age. Led by the Italian Matteo Roverato, who is now a post-doctorate researcher at the University of São Paulo, the team of researchers studied the typical fractured texture—similar to puzzle pieces—found in sediments around the site of the historic avalanche of debris from the sides of the mountain.

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