Almazbek Torgoev

Landslide Susceptibility, Hazard and Risk Mapping in Mailuu-Suu, Kyrgyzstan

This paper presents the results of landslide susceptibility and landslide hazard mapping together with preliminary landslide risk studies on qualitative basis. The target area is situated in the south of Kyrgyzstan, Central Asia, in the valley of Mailuu-Suu River. There are several uranium waste tailings situated in the target area and there is the risk that landslide activity can result in an environment catastrophe through destruction of waste tailing and damming of river channel leading to flooding of radioactive material. For remediation measures and risk mitigation there is the need to have reliable estimates of landslide susceptibility and hazard in target area on local and regional scales.

Rockslides in the Open Pit of Kumtor Goldmine (Kyrgyzstan)

The high-elevation Kumtor mine is located in the Central Tien Shan in the permafrost and active glaciers area. This area is characterized by extreme continental climate. The average annual temperature in the mine area is −7.8 °C with fluctuations in the average minimum temperature of −28.8 °C in January up to 1.7 °C in July. The average annual precipitation is 350–400 mm, a quarter of which falls as rain and the rest in the form of snow. Harsh climatic conditions in the area, the presence of mountain glaciers and permafrost rocks, diversity of terrain, rock types, seasonal freezing and melting of the rocks and soil together with global warming and large-scale anthropogenic impact cause active development of cryogenic gravitational processes. The most dangerous among them are repeated slumping and sliding of the north-eastern wall of the Central pit. The report presents the results of geotechnical studies and analysis of the main reasons for the failure of the pit walls, which include melting of the permafrost rocks at the top of the pit and glacial water inflow into the tectonic disruption zone.

Parametric Numerical Study of Seismic Slope Stability and Verification of the Newmark Method

2D dynamic modelling of seismic slope stability is applied to a landslide-prone area in Central Asia, the Mailuu-Suu Valley, situated in the south of Kyrgyzstan. The calculations are made with models constructed from five long profiles located in the target area, presenting different geological, tectonic and morphological settings. These input data were extracted from a 3D structural geological model built with the GOCAD software. Geophysical and geomechanical parameters were defined on the basis of results obtained by multiple surveys performed in the area over the past 15 years. These include geophysical investigation, seismological experiments and ambient noise measurements. Dynamic modelling of slope stability is performed with the UDEC version 4.01 software that is able to compute deformation on the basis of discrete elements. Inside these elements pure elastic materials (similar to rigid blocks) were used. Various parameter variations were tested to assess their influence on the final outputs. The total parametric study involved more than 50 different models (about 400 computation hours). Preliminary results allow us to evaluate the influence of topography and geology on the amplification of Areas Intensity, which is a very important parameter needed for the computation of Newmark displacements using different GIS approaches [Jibson et al. (US Geol Surv Open file report 98–113,1998); Miles and Ho (Soil Dyn Earth Eng 18:305–323,1999), among others]. The final results of our studies should allow us to define the limitations of the simplified GIS-based Newmark displacement modelling; thus, the verified method would make landslide susceptibility and hazard mapping in seismically active regions more reliable.