Flow Slides in Uzbekistan: Overview and Case Studies

Paper describes in brief spatial distribution of the landslide-prone areas in Uzbekistan, temporal evolution of these phenomena during last 60 years and organization of the landslide monitoring in in the country. Special emphasis is given to flow slides in loess and clayey often triggered by the prolonged low-frequency seismic vibrations of the distant deep Hindu Kush earthquakes. Three typical case studies of such flow slides that occurred in the recent years are presented and their evolution and motion characteristics are described. Seismometric measurements performed at the source zone of the Achiyak landslide prove that the vibration frequency of the deep Hindu Kush earthquakes coincides with natural frequency of the loess blanketing the slopes in the foothill areas of Uzbekistan that cause resonance effects. Multi-stage evolution of large flow slides some of which transform into mud flows that can last from several days to several years is described by examples of the Khandiza and the Otbokarsai flow slides.