Geological prerequisites for landslide dams’ disaster assessment and mitigation in Central Asia

Landslide dams’ hazard assessment aimed to disaster mitigation requires knowledge of the origin of hazardous phenomena, its triggering factors, magnitude, spatial distribution, recurrence, as well as characteristics of their possible secondary and tertiary effects. These hazards identification and quantification can be derived from detail geological and geomorphic study of the present and past river-damming landslides and related phenomena such as evidence of outburst floods. Several historical catastrophes that occurred in the Central Asian region due to formation and/or breach of landslide dams are described briefly and case studies demonstrating various manifestations of landslide damming in the Central Asia region are discussed with special emphasis on those topics, which still remain unsolved or controversial. These are: (1) the landslide versus moraine interpretation of the Pamirs’ natural blockages origin, (2) the relationship between formation of large-scale bedrock landslides and seismicity, which is critically important for both landslide and seismic hazard assessment, (3) morphological and structural peculiarities of large-scale bedrock landslides—the main type of river-blocking slope failures that predetermine magnitude of river damming, its longevity and character and rate of dams’ breach. The importance of the detailed study of the past breached dams, as the analogues of the existing and future hazardous blockages is discussed in the conclusive remarks.