HISTORICAL AVALANCHES Sample Clauses

HISTORICAL AVALANCHES. The largest known ice fall the Alps happened on 11 September 1895 in the Alps in Switzerland, where the part of a glacier (five million m3) slipped off from the summit area of Altels and fell alpine pasture killing six people and 158 cows (Fig.3.1) 1896, Xxxxxxxxxxxxx Both authors have attempted to analyse the possible causes of this detachment. The prominent curve-shaped fracture line at the head of the niche left by the avalanche indicates failure under tensile stresses. Basal and shear adhesion and shear resistance at lateral abutments were the stabilizing forces. The gravitational pull and the sum of the retaining forces critical equilibrium from which the spontaneous release of the avalanche of the retaining forces failed. Probably this by warming of a frontal zone frozen to the bedrock. As a consequence, the extent of this zone became reduced and the the still frozen parts increased up to the shear strength of ice. Very warm in the preceding the ice support this hypothesis. More recently, on 30 August a major portion of the terminus of Allalingletscher (Valais, Switzerland) detached unexpectedly, slid down a rock slope of some over a vertical distance of 400 m and for further 400 m across the flat bottom of the valley, claiming 88 victims at the construction site (Fig.3.2). The volume of the ice avalanche was estimated at 0.5- 1 Subsequent glaciological investigations showed that the ice avalanche a of enhanced motion as a result of intensive bed-slip of an even larger mass that which broke off. It could be inferred that enhanced sliding on the rock occured already some 2-3 weeks prior to the sudden slump of the avalanche. It be that such active phases with enhanced sliding motion took place quite regularly of one to three years, usually in late summer or in fall, but always ending at of without any significant ice fall occurence. Similar movement be obseived on many other steep glacier tongues. This active phase was a necessary bur riot condition for the lower part of the tongue to slide off. convex bed topography and an unfortunate mass distribution, combined with the active phase, role that catastrophe (Xxxxxxxxxxxxx 1981, Xxxxxxxxxxxxx and Xxxxxx 1978). - - The road was blocked over a distance of 20 m and the air pressure injured three persons and knocked down some hikers (Xxxxxxxx and Funk 1998). The Gutzgletscher, a so-called hanging glacier, is situated on a moderately inclined bed in the very steep north-west face of Wetterhorn mountain and e...