|
Half a mile
in one month! The glacier normally moves 650 to 1300 feet (200 to 400 meters) in an entire year. The sudden downhill slide raised concern among glaciologists and emergency management groups about a potential glacial outburst flood that could flow down into the Vanch River valley. The mud-covered terminus of the glacier now blocks the Abdukagor River and is forming a glacial lake behind a wall of ice 500 to 650 feet (150 to 200 m) high and more than 1,000 feet (300 m) across. Cracks and ice tunnels may be allowing some water to flow through; a bridge across the river downstream has been washed out from one water surge so far. Located in southern Tajikistan in the Pamir Mountains, Medvezhiy (Bear) Glacier is roughly 10 miles (16 km) long, and drains out of the Academii Nauk (Academy of Sciences) Range. The upper end of Medvezhiy sits 14,800 feet (4,500 m) above sea level, with the terminus at roughly 9,900 feet (3,000 m). It is described by glaciologists as a pulsating glacier with periodic surging; the most recent surges were 1989 and 2001. Major surges in
1963 and 1973 caused the formation of ephemeral (short-lived) lakes that swelled
behind the ice. In each case, the glacier surged as much as 1.2 miles (2 km)
down the valley and blocked the Abdukagor River with ice dams as much as 330
feet (100 m) high. When the ice dams broke, more than 20 million cubic meters of
water flowed down the river. No lives were lost in those instances, but
infrastructure damage was significant, according to reports. Scientists have
regularly surveyed the area since the 1960s. |
