On July 17, 130 million cubic meters of ice and rock suddenly detached from a glacier in Tibet, plunging six tenths of a mile into the depths, killing nine shepherds along with 350 sheep and 110 yaks. Scientists were baffled. By examining satellite imagery before and after the event, they believe it is an example of a rare glacial wave where a glacier is moving at 10 to 100 times its speed. Some researchers believe that high altitude climate change can trigger such surges.
NASA
“It doesn’t make sense,” said Tian Lide, a glaciologist at the Institute for Tibetan Plateau Research (ITPR) at the Chinese Academy of Sciences in Beijing, who runs a research station in Rutog. Most avalanches occur on slopes of 25 to 45 degrees, but the Rutog Avalanche, as this event is called, began in a flat area around 17,000 to 20,000 feet above sea level. When it settled, it covered an area of nearly 3.8 square miles to a depth of nearly 30 feet. The only other event of comparable size was the Kolka Glacier in the Caucasus in 2002. This avalanche killed 140 people.
A whole tongue of the Rutog Glacier in northwestern Tibet collapsed at once. Lide found that the glacier crashed with such force that it widened the gully in which it came to a standstill. Two different satellites took before and after images of the area. NASA’s Operational Land Imager took an image on June 24, just under a month before the avalanche. The European Space Agency’s Sentinel-2 satellite captured an image of the debris field on July 21, days later. The pre-collapse images showed that the glacier was already showing signs of change.
Glacial thrusts can be caused by meltwater at the base of the glacier, which essentially lubricates the surface over which it flows. These types of surges can have a sudden onset and a very high flow rate. There are many glacier-type glaciers in western Tibet.
Researchers from Moscow State University and the University Center for Engineering Geodynamics and Monitoring in Moscow examined the Kolka avalanche on site. Glacier turns are not new there; Events that date back at least to 1902 are known. They found grooves in the moraine rocks that they had never seen before.
“Moraine rocks are not scraped off the glacier because they move with it,” said Dmitry Petrakov, a geologist at Moscow State University. “But at Kolka the collapse happened so quickly that the ice mass simply flew over the moraine and created streaks several millimeters deep in minutes.”
They found that the avalanche was moving at an enormous speed, maybe up to 180 km / h. They concluded that it was a surge event.
https://www.youtube.com/watch?v=FH_vQPWZtrk
A year after the Kolka collapse, researchers found the area still unstable. In the days after the Rutog avalanche, cracks appeared in nearby glaciers. Temperatures on the Tibetan plateau have risen by 0.4 degrees Celsius per decade, twice the global average. A tenth of the permafrost has melted in the last decade alone. Rapidly melting glaciers have increased the number of lakes by 14 percent since 1970, and 80 percent of the existing lakes have grown and flooded towns and pastures. In addition, rainfall in the region has increased 12 percent since 1960.
EcoWatch reported on the problems in this area known as the “Third Pole” on August 26th. The Himalayas and the Tibetan Plateau hold the largest ice mass on earth after the polar regions. The loss of these glaciers threatens the water supplies of 1 billion people in China, India and Tibet, Nepal, Bhutan and Southeast Asia.
Mount Everest climbers can one day ice-free https://t.co/8rTp6XI25o via @EcoWatch #climatechange https://t.co/sMCOeuDREu. climb
– Klimarat (@Klimarat) 1472691961.0
In response to the Rutog avalanche, China Radio International reported, “Experts believed that the icefall was a result of global warming, which caused the glaciers to melt and rupture.”
The victims of the Rutog avalanche were residents of the village of Dungru in Rutog County in southwest China’s Tibet Autonomous Region.
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