Characteristics, hazard conditions, and research progress of shattered mountains in the Yarlung Zangbo Suture Belt, Tibet, China

Shattered mountains in the Yarlung Zangbo Suture Belt, Tibet, were formed by the collision movement of Indo-Eurasian plates superimposed with recent strong seismic activities. They are characterized by complex lithologic structures, strong tectonic actions, and significant deformation, which are beneficial to failure under certain extreme mechanical conditions. Thus, the shattered mountain problem becomes one of the major geological safety challenges in the construction and operation of the border towns and major engineering projects. Based on field investigation and geological explorations, this paper deeply analyzed the characteristics of the shattered mountains in the Yarlung Zangbo Suture Belt. Hazard conditions were summarized from three aspects: lithological combination, tectonic activities, and rock mass structure. Moreover, this paper overviewed the latest research results, including engineering geological properties of rock masses in suture zones, structural characteristics of the shattered mountains, seismic dynamic responses of mountain slopes, mountain failure mechanism induced by strong earthquakes, and relative research methods. Main conclusions include: 1) The shattered mountains in the Yarlung Zangbo Suture Belt are controlled by the Motuo active fault system and were subjected to the Great Chayu M 8.6 earthquake in 1950; the mountain structures were loosened, and the rock masses were deformed, which were prone to large-scale instability under intense disturbance. 2) The scattered mountains in the Yarlung Zangbo Suture Belt have special disaster-prone geological structures, and the favorable conditions are mainly governed by the particular lithological combination, strong tectonic activity, and loose rock mass structure. 3) At present, it is urgent to establish a detailed geomechanical model of the shattered mountains in the Yarlung Zangbo Suture Belt, to analyze the damage and failure mechanism of the tectonic mélange rock masses, and to explain the dynamic response and instability mechanism of the shattered mountains in the suture zone under strong earthquakes. In the end, it is suggested to choose Badengze Mountain in Motuo county as the key study case to systematically analyze the failure mechanism of the shattered mountains in the Yarlung Zangbo Suture Belt, which would support the prevention and reduction of major geological disasters on the Qinghai-Tibet Plateau.