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article imageWatch dramatic collapse of Perito Moreno glacier bridge

By JohnThomas Didymus     Feb 12, 2013 in Environment
Christian Grosso was visiting a glacier in Argentina's Patagonia region when he had the opportunity to witness a massive ice bridge connected to the glacier rupture and fall into the lake below, causing a big splash and wave.
Fortunately, Grosso had a camera ready to capture the event.
NASA Earth Observatory reports the glacier Perito Moreno is one of the most famous in Patagonia, the southern tip of South America. It is also the largest at 30 kilometers long. According to NASA Earth Observatory: "The glacier descends from the Southern Patagonian Icefield in the Andes Mountains—down into the water and warmer altitudes of Lago Argentino at 180 meters above sea level (see map diagram below)."
Perito Moreno glacier
Perito Moreno glacier
NASA Earth Observatory
Perito Moreno's fame arises from the fact that it periodically cuts off the major southern arm (Brazo Rico) of Lake Argentino forming a dam. Digital Journal reports that the glacier advances across the lake until it connects to the shoreline opposite. The ice bridge formed, according to NASA Earth Observatory, is not floating but "grounded" so that it effectively forms a natural ice dam which prevents lake water from moving between the two bodies of water. The natural ice dam causes meltwater flowing in from the south to raise water levels in Brazo Rico by as much as 30 meters above the level of the water in Lago Argentino (see diagram above).
The great pressure of the dammed water finally causes the ice bridge to rupture in a dramatic spectacle that made the glacier a major tourist attraction in the region. NASA Earth Observatory reports that the process repeats every four to five years as the glacier begins reaching towards the opposite shoreline again after a rupture.
According to Live Science, Grosso witnessed only a relatively minor rupture of the ice bridge. A major incident occurs once every four to five years when Brazo Rico's water level rises as much as 30 meters higher than water in Lago Argentino causing a spectacular collapse.
Amazing Planet reports that NASA scientist Jim Foster, said: "This glacier is somewhat unique in that its path takes it across an arm of a large lake. Most glaciers don't have such trajectories, so bridging and tunneling, at least at this scale, is rather rare."
Live Science reports Grosso witnessed and filmed the dramatic spectacle on Saturday, Jan. 19, at about 7:15 p.m. local time, while there were only 20 to 30 visitors.
The last time a major rupture occurred was in March 2012. According to Live Science, what Grosso witnessed was a minor incident caused by the melting of the ice bridge left over from the 2012 collapse.
Digital Journal reported the last major incident in March 2012.
More about glacier bridge, Collapse, Glacier