Second massive 'mystery' avalanche spotted from space

Monday, October 24, 2016, 8:32 PM - NASA has spotted a second 'mystery' avalanche, right beside an earlier slide that killed several people and livestock in a Tibetan village.

The first avalanche, from a glacier in Tibet's Aru Range, happened in July this summer, killing nine people and more than four hundred livestock. It was such a massive slide that it filled the valley with 10 square kilometres of debris, up to 30 m deep in places, and scientists have struggled to explain why it occurred.

Now, a newly released satellite images of second avalanche, which occurred in September, has deepened the mystery.

"Even one of these gigantic glacier avalanches is very unusual," University of Oslo glaciologist Andreas Kääb said in a release from NASA Earth Observatory. "Two of them within close geographical and temporal vicinity is, to our best knowledge, unprecedented."

BELOW: Before and after images of the first avalanche

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It's a headscratcher for the experts, who say the land is relatively flat, there hadn't been excessive rainfall prior to the first slide, and temperatures had been normal.

They don't have an answer yet, but studies of the first slide, and images taken before the glacier's collapse, found some changes to its height and surface suggesting it was in the process of a "surge", a downhill flow of ice on the glacier that happens unusually fast -- though NASA says there are "no documented cases" of such surges causing collapses like this.

Lubrication beneath the glacier can be a factor in rapid movement, and the scientists say there's evidence of the beginning of a surge in mid 2015 may have stalled, causing a buildup of extra water beneath it that exacerbated the 2016 collapse.

The scientists used their findings to help them detect signs a second avalanche might be imminent, and a warning to local authorities actually arrived mere hours after the one in the top image occurred. There have been no reports of injuries.

Though NASA says there is no evidence the one caused the other, "the similarities between the two events imply that shared factors — such as short-term weather conditions, longer term climate change, and the underlying geological or topographic environment—may have played a role."

SOURCE: NASA Earth Observatory