On September 16th, 1986, an ice avalanche from a hanging glacier near the K2 peak at 7800 m asl, Karakorum, triggered a massive avalanche of ice and snow. Ice and snow, impacting on the path, formed a dust cloud at the advancing tip. Grounding on the firn basin surface, ice and snow broke into fine powder and covered the whole basin. Fine powder of the dust cloud rose up to 500–600 m and drifted 4–5 km away. On the basis of field observations and measurements, topography and weather, conditions of the avalanche formation are analyzed. Judging by the data obtained, the avalanche was extremely large, its vertical descend being 2500 m, the maximum motion speed 124 m/s, volume of the avalanche mass 2 × 105 m3 to 107 m3, and impact pressure, as the avalanche grounded, 2.3 × 106 Pa. It could have been one of the largest avalanches ever recorded, causing danger for mountaineering and expedition activities in this area.
KeywordsDust Cloud Impact Pressure Runout Distance Vertical Descent Large Avalanche
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