ИСТИНА

Several typical examples of large-scale rockslides from the Central Asia region with bipartite deposits that have compact proximal and highly mobile avalanche-like distal parts are described. Such case studies illustrate partial involvement of rockslide debris in accelerated motion resulting in its extra-mobility. Besides long runout many of them are characterized by the abrupt change of the direction of rock avalanche motion relative to the direction of the initial slope failure, so that they can affect areas that otherwise would be considered as safe. It is hypothesized that such bipartition is caused by the fluidization of the frontal part of rockslide body that reaches the valley bottom first or by the momentum transfer from the entire collapsed rock mass to its portion retaining possibility of further motion after its collision with an obstacle or after entering sharp valley constriction.