Amateur photographer Christian Grosso got a surprise recently when he visited a glacier in Argentina's Patagonia region: an enormous ice bridge connected to the glacier ruptured and fell, causing a huge wave in the lake below.
Luckily he had his camera to capture the event. And another visitor caught a video of the ice falling.
The glacier, known as Perito Moreno, is one of the largest in Patagonia, a region at the southern tip of South America, according to the NASA Earth Observatory. Perito Moreno differs from other glaciers in that it periodically cuts off the major southern arm of Lake Argentino, known as Brazo Rico, by forming a natural dam and preventing water from transferring between the two bodies of water.
"This glacier is somewhat unique in that its path takes it across an arm of a large lake," NASA scientist Jim Foster told OurAmazingPlanet. Foster also curates the Earth Science Picture of the Day, which featured Grosso's photo. "Most glaciers don't have such trajectories, so bridging and tunneling, at least at this scale, is rather rare."
Grosso got to witness the rare event on Saturday, Jan. 19, at about 7:15 p.m. local time; there were only 20 to 30 visitors present at the time, he said. Luckily, Grosso was far enough away that the rush of water didn't affect him, he told OurAmazingPlanet.
This was but a relatively minor rupture of the glacier, however. Every four to five years Brazo Rico's water levels swell as much as 98 feet (30 meters) higher than those in Lake Argentino. When the stress is too much, the glacier catastrophically ruptures, according to the Earth Observatory.
That last happened in March 2012; this latest burst, witnessed by Grosso, resulted from the melting of the ice bridge that was left over from that 2012 collapse, which had hollowed out an enormous hole through the glacier.
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.