Extremely large rockslides and rock avalanches in the Tien Shan Mountains, Kyrgyzstan

Abstract

Most systematic research on large rock-slope failures is geographically biased towards reports from Europe, the Americas, the Himalayas and China. Although reports exist on large rockslides and rock avalanches in the territory of the former Soviet Union, they are not readily available, and few translations have been made. To begin closing this gap, we describe here preliminary data from field reconnaissance, remote sensing and geomorphometry of nine extremely large rock-slope failures in the Tien Shan Mountains of central Kyrgyzstan. Each of these catastrophic and prehistoric failures exceeds an estimated 1 km 3 in volume, and two of them involve about 10 km 3 . Failure of rock slopes in wide valleys favoured the emplacement of hummocky long-runout deposits, often spreading out over >10 km 2 , blocking major rivers. Most of these gigantic slope failures are located on or near active faults. Their spatial clustering and the high seismic activity in the Tien Shan support the hypothesis that strong seismic shaking caused or triggered most of these large-scale rock-slope failures. Nevertheless detailed field studies and laboratory analyses will be necessary to exclude hydroclimatic trigger mechanisms (precipitation, fluvial undercutting, permafrost degradation), and to determine their absolute ages, frequency and the large-landslide hazard of central Kyrgyzstan.

Tien Shan Geohazards Database: Earthquakes and landslides

“…3). It has an estimated volume of 5-6 km 3 (and may be even more than 6 km 3 according to Strom and Korup, 2006). This volume is only exceeded by the already breached rockslide dam of Beshkiol rockslide located in the south-east of zone Z1.…”

“…The landslide inventory was compiled from various digital maps of rockslides produced by the authors (see, e.g., Strom and Korup, 2006, for a description of the largest identified rockslides) as well as landslide maps created in the frame of Master's Theses completed at the University of Liege, Belgium (Schlögel, 2009;Dupont, 2011;Burette, 2012). Additionally, more than 1800 other landslides have been mapped recently in soft sediments (around the Fergana Basin and along the southern border of the Tien Shan, see landslides outlined in yellow near the zones Z3, Z4, Z5 in Fig.…”

Large-Scale Rockslide Inventories: From the Kokomeren River Basin to the Entire Central Asia Region (WCoE 2014–2017, IPL-106-2)

“…Most of the case studies identified in this area were described in Abdrakhmnatov and Strom (2006), Hartvich et al (2008), Strom (1994Strom ( , 1996Strom ( , 2006Strom ( , 2010Strom ( , 2013aStrom ( , b, c, d, 2015, Strom and Groshev (2009), Strom and Korup (2006), Strom and Stepanchikova (2008), and Strom and Zhirkevich (2013).…”

Combining Seismic Noise Techniques for Landslide Characterization

“…The first documented observations of slope instabilities in this region date to the end of the 19th century (Ignatiev 1886). However, several of these mass movements were neither documented nor did they cause significant damages, since they occurred in remote and sparsely inhabited areas (Strom and Korup 2006).…”