The Source of the Catastrophe

Figure 6
[9]  The upper reaches of the Genaldon Ravine close up in the south by a chain of three majestic peaks, namely, Kazbek (5033 m high), Maili-Khokh (4598 m), and Dzhimarai-Hoh (4780 m), all being the constituents of the Bokovoi (Lateral) Range of the Central Caucasus. The northern Dzhimarai-Hoh spur, including the also significant Shau-Khokh Peak (4636 m) shuts off the gorge from the west and northwest, forming a basin which is occupied by the Kolka small glacier, 3.1 km long. The system of these peaks is combined, conventionally, into an individual high-mountain massif, known as the Kazbek-Dzhimarai Massif. Restricted to this massif is a glaciation center, measuring 13 km 2 in area. Its largest glacier is the Maili Glacier covering an area of 7 km2. Its feeding zone embraces the northwestern slopes of the Kazbek Range and the northern slopes of the Maili-Khokh Volcano. It drains to the Genaldon Ravine in the form of a huge ice fall. This glacier tongue descends to the elevation of 2300 m (Figure 6).

Figure 7
[10]  In contrast to the Maili classical valley glacier, the Kolka Glacier is classified as a glacier of a cirque-valley avalanch feeding. The feeding zone of this glacier consists of the firn fields of the northeastern Dzhimarai-Hoh slopes having no contacts with the glacier itself. Their thicknesses vary from 40 m to 70 m. Their firn masses flow to the glacier tongue in an avalanche manner over a distance of about one kilometer along a steep (about 40o) slope, involving a significant volume of a lithogenous material. This factor controls the formation of a dense mantle of the surface moraine covering almost the whole of the glacier. The thickness of the moraine cover grows closer to the frontal part of the tongue (absolute elevation of 2960 m) and amounts to 80 cm. The glacier bed is inclined slightly (6-7o) in the east-west direction, this resulting in the relatively low dynamics of the plastic deformation of its body. Single fissures were observed only in its rear (Figure 7).


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