Abstract
Massive rock avalanches form some of the largest landslide deposits on Earth and are major geohazards in high-relief mountains. This work reinterprets a previously reported glacial deposit in the Alai Valley of Kyrgyzstan as the result of an extremely long-runout, probably coseismic, rock avalanche from the Komansu River catchment. Total runout of the rock avalanche is ~28 km, making it one of the longest-runout subaerial non-volcanic rock avalanches thus far identified on Earth. This runout length appears to require a rock volume of ~20 km3; however, the likely source zone in the Trans Alai range likely contained just ~4 km3 of rock, and presently, the deposit has a volume of only 3–5 km3; a pure rock avalanche volume of >10 km3 is therefore impossible, so the event was much more mobile than most non-volcanic rock avalanches. Explaining this exceptional mobility is crucial for present-day hazard analysis. There is unequivocal sedimentary evidence for intense basal fragmentation, and the deposit in the Alai Valley has prominent hummocks; these indicate a rock avalanche rather than a rock-ice avalanche origin. The event occurred 5,000–11,000 yr B.P., after the region’s glaciers had begun retreating, implying that supraglacial runout was limited. Current volume—runout relationships suggest a maximum runout of ~10 km for a 4-km3 rock avalanche. Volcanic debris avalanches, however, are more mobile than non-volcanic rock avalanches due to their much higher source water content; a rock avalanche containing a similarly high water content would require a volume of about 8 km3 to explain the extreme runout of the Komansu event. Rock and debris avalanches can entrain large amounts of material during runout, with some doubling their initial volume. The best current explanation of the Komansu rock avalanche thus involves an initial failure of ~4 km3 of rock debris, with high water content probably deriving from large glaciers on the edifice that subsequently entrained ~4 km3 of valley material together with further glacial ice, resulting in a total runout of 28 km. It is as yet unclear whether glacial retreat has rendered a present-day repetition of such an event impossible.
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References
Abramowski U, Bergau A, Seebach D, Zech R, Glaser B, Sosin P, Kubik PW, Zech W (2006) Pleistocene glaciations of Central Asia: results from 10Be surface exposure ages of erratic boulders from the Pamir (Tajikistan), and the Alay–Turkestan range (Kyrgyzstan). Quat Sci Rev 25:1080–1096
Arrowsmith JR, Strecker MR (1999) Seismotectonic range-front segmentation and mountain-belt growth in the Pamir-Alai region, Kyrgyzstan (India-Eurasia collision zone). Geol Soc Am Bull 111(11):1665–1683
Barth NC (2013) The Cascade rock avalanche: implications of a very large Alpine fault-triggered failure, New Zealand. Landslides 1-15. doi: 10.1007/s10346-013-0389-1
Buech F, Davies TRH, Pettinga JR (2010) The Little Red Hill seismic experimental study: topographic effects on ground motion at a bedrock-dominated mountain edifice. Bull Seismol Soc Am 100:2219–2229
Burtman VVS, Molnar PH (1993) Geological and geophysical evidence for deep subduction of continental crust beneath the Pamir (Vol. 281). GSA Bookstore
Coutand I, Strecker MR, Arrowsmith JR, Hilley G, Thiede RC, Korjenkov A, Omuraliev M (2002) Late Cenozoic tectonic development of the intramontane Alai Valley,(Pamir‐Tien Shan region, Central Asia): An example of intracontinental deformation due to the Indo‐Eurasia collision. Tectonics 21(6):1053–1072
Crosta G, Harmanns RL, Murillo PV (2012) Large rock avalanches in southern Perù: the Cerro Caquilluco - Cerrillos Negros rock slide - avalanche (Tacna, Tomasiri, Perù). Geophysical Research Abstracts. 14
Dade WB, Huppert HE (1998) Long-runout rockfalls. Geol 26(9):803–806
Davies TRH (1982) Spreading of rock avalanche debris by mechanical fluidization. Rock Mech 15(1):9–24
Davies TR, McSaveney MJ (2002) Dynamic simulation of the motion of fragmenting rock avalanches. Can Geotech J 39(4):789–798
Davies TRH, McSaveney M (2009) The role of rock fragmentation in the motion of large landslides. Engineering Geology 109:67–79
Davies TRH, McSaveney MJ (2012) Mobility of long-runout rock avalanches. In: Clague JJ, Stead D (eds) Landslides: Types, Mechanisms and Modeling: Cambridge University Press: 50-58. ISBN-13: 9781107002067
Davies TRH, McSaveney M, Kelfoun K (2010) Runout of the Socompa volcanic debris avalanche, Chile: a mechanical explanation for low basal shear resistance. Bull Volcanol 72(8):933–944
Delaney KB, Evans SG (2014) The 1997 Mount Munday landslide (British Columbia) and the behaviour of rock avalanches on glacier surfaces. Landslides. 1-18
Dufresne A, Davies TRH, McSaveney MJ (2010) Influence of runout-path material on emplacement of the Round Top rock avalanche. New Zealand Earth Surf Process Landf 35(2):190–201
Eisbacher GH (1979) Cliff collapse and rock avalanches (sturzstroms) in the Mackenzie Mountains, northwestern Canada. Can Geotech J 16(2):309–334
Erismann TH (1979) Mechanisms of large landslides. Rock Mech 12(1):15–46
Evans SG, Clague JJ (1988) Catastrophic rock avalanches in glacial environments. Proceedings of the 5th International Symposium on. Landslides 2:1153–1158
Evans SG, Bishop NF, Smoll LF, Murillo PV, Delaney KB, Oliver-Smith A (2009) A re-examination of the mechanism and human impact of catastrophic mass flows originating on Nevado Huascarán, Cordillera Blanca, Peru in 1962 and 1970. Eng Geol 108:96–118
Fan G, Ni JF, Wallace TC (1994) Active tectonics of the Pamirs and Karakorum. J Geophys Res Solid Earth (1978–2012) 99.B4:7131–7160
Glicken H (1996) Rockslide-debris avalanche of May 18, 1980, Mount St. Helens volcano. Washington. US Geol. Surv. Open-file Report. 96-677
Hancox GT, Perrin ND (1994) Green Lake landslide: a very large ancient rock slide in glaciated terrain, Fiordland. Institute of Geological and Nuclear Sciences Limited, New Zealand
Hauser A (2002) Rock avalanche and resulting debris flow in Estero Parraguirre and Rio Colorado, Region Metropolitana, Chile. In: Evans SG, DeGraff JV (eds) Catastrophic landslides: effects, occurrence, and mechanisms: Boulder, vol 15, Colorado, Geological Society of America Reviews in Engineering Geology., pp 135–148
Hewitt K (1999) Quaternary moraines vs catastrophic rock avalanches in the Karakoram Himalaya, northern Pakistan. Quaternary Res 51(3):220–237
Hewitt K (2001) Catastrophic rockslides and the geomorphology of the Hunza and Gilgit River valleys, Karakoram Himalaya. Erdkunde 55:72–93
Hsü KJ (1975) Catastrophic debris streams (sturzstroms) generated by rockfalls. Geol Soc Am Bull 86(1):129–140
Huggel C, Zgraggen-Oswald S, Haeberli W, Kääb A, Polkvoj A, Galushkin I, Evans SG (2005) The 2002 rock/ice avalanche at Kolka/Karmadon, Russian Caucasus: assessment of extraordinary avalanche formation and mobility, and application of QuickBird satellite imagery. Nat Haz Earth Sys Sci 5:173–187
Hungr O, Evans SG (2004) Entrainment of debris in rock avalanches: an analysis of a long run-out mechanism. Geol Soc Am Bull 116.9-10:1240–1252
Ibetsberger HJ (1996) The Tsergo Ri landslide: an uncommon area of high morphological activity in the Langthang valley. Nepal Tectonophysics 260:85–93
Krumbiegel C, Schurr B, Orunbaev S, Rui H, Pingren L, TIPAGE Team (2011) The 05/10/2008 Mw 6.7 Nura earthquake sequence on the Main Pamir Thrust. Geophys Res Abstr 13:4846
Kurdiukov KV (1964) The latest tectonic movements and evidence of the large seismicity at the Northern slope of the Zaalai Range. In: Belousov VV et al. (eds) Activated zones of the crust, the latest tectonic movements and seismicity: Moscow
Le Corvec N (2005) Socompa volcano destabilisation (Chile) and fragmentation of debris avalanches. MSc thesis, Université Blaise Pascal, Clermont-Ferrand, France, 67p
Legros F (2002) The mobility of long-runout landslides. Eng Geol 63(3):301–331
Lienkaemper JJ, McFarland FS, Simpson RW, Bilham RG, Ponce DA, Boatwright JJ, Caskey SJ (2012) Long-term creep rates on the Hayward fault: evidence for controls on the size and frequency of large earthquakes. Bull Seismol Soc Am 102(1):31–41
Lucas A, Mangeney A (2007) Mobility and topographic effects for large Valles Marineris landslides on Mars. Geophys Res Lett 34.L10201:1–5
Lucchitta BK (1978) A large landslide on Mars. Geol Soc Am Bull 89:1601–1609
McColl ST, Davies TRH (2010) Evidence for a rock-avalanche origin for ‘The Hillocks’ “moraine”, Otago, New Zealand. Geomorphology 127:216–224
McSaveney MJ (1978) Sherman glacier rock avalanche, Alaska, USA. Rockslides and Avalanches 1:197–258
McSaveney MJ (2002) Recent rockfalls and rock avalanches in Mount Cook national park, New Zealand. Catastrophic Landslides: Eff, Occurrence, and Mech 15:35–70
Melosh HJ (1979) Acoustic fluidization: a new geologic process? J Geophys Res Solid Earth (1978–2012) 84.B13:7513–7520
Nikonov AA, Vakov AV, Veselov IA (1983) Seismotectonics and earthquakes in the convergent zone between the Pamir and Tien Shan (in Russian). Nauka, Moscow
Philip H, Ritz JF (1999) Gigantic paleolandslide associated with active faulting along the Bogd fault (Gobi-Altay, Mongolia). Geol 27(3):211–214
Pollet N, Schneider JL (2004) Dynamic disintegration processes accompanying transport of the Holocene Flims sturzstrom (Swiss Alps). Earth Planet Sci Lett 221(1):433–448
Prager C, Krainer K, Seidl V, Chwatal W (2006) Spatial features of Holocene sturzstrom-deposits inferred from subsurface investigations (Fernpass rockslide, Tyrol, Austria). Geo Alp 3:147–166
Quantin C, Allemand P, Mangold N, Delacourt C (2004) Ages of Valles Marineris (Mars) landslides and implications for canyon history. Icarus 172(2):555–572
Reznichenko NV, Davies TRH, Shulmeister J, Larsen SH (2012) A new technique for identifying rock avalanche–sourced sediment in moraines and some paleoclimatic implications. Geol 40(4):319–322
Reznichenko N, Davies TRH, Robinson TR, De Pascale G (2013) Rock avalanche deposits in Alai Valley, Central Asia: misinterpretation of glacial record. EGU Gen Assem Conf Abstr 15:182
Robert NJ, Evans SG (2013) The gigantic Seymareh (Saidmarreh) rock avalanche, Zagros fold-thrust belt. Iran J Geol Soc 170(4):685–700
Scheidegger AE (1973) On the prediction of the reach and velocity of catastrophic landslides. Rock Mech 5(4):231–236
Schneider D, Huggel C, Haeberli W, Kaitna R (2011) Unraveling driving factors for large rock–ice avalanche mobility. Earth Surf Proc Land 36(14):1948–1966
Shatravin VI (2000) Reconstruction of Pleistocene and Holocene glaciations in Tien-Shan and Pamir: New Results. Pamir and Tien-Shan: Glacier and Climate Fluctuations during the Pleistocene and Holocene: International Workshop
Shreve RL (1966) Sherman landslide, Alaska. Science 154(3757):1639–1643
Siebert L (1984) Large volcanic debris avalanches: characteristics of source areas, deposits, and associated eruptions. J Volcanol Geoth Res 22(3):163–197
Sigurd̷sson O, Williams Jr RS (1991) Rockslides on the Terminus of Jökulsárgilsjökull, Southern Iceland. Geogr. Ann. Ser. A. Phys. Geogr. 129-140
Sosio R, Crosta GB, Chen JH, Hungr O (2012) Modelling rock avalanche propagation onto glaciers. Quaternary Sci Rev 47:23–40
Strasser M, Schlunegger F (2005) Erosional processes, topographic length-scales and geomorphic evolution in arid climatic environments: the ‘Lluta collapse’, northern Chile. Int J Earth Sci 94(3):433–446
Strecker MR, Hilley GE, Arrowsmith JR, Coutand I (2003) Differential structural and geomorphic mountain-front evolution in an active continental collision zone: the northwest Pamir, southern Kyrgyzstan. Geol Soc Am Bull 115(2):166–181
Strom A (2006) Morphology and internal structure of rockslides and rock avalanches: grounds and constraints for their modeling. Landslides from Massive Rock Slope Failures 49:305–326
Strom A (2014) Catastrophic slope processes in glaciated zones of mountainous regions. In: Sahn W et al (eds.) Landslides in cold regions in the context of climate change
Turnbull JM, Davies TRH (2006) A mass movement origin for cirques. Earth Surf Process Landf 31(9):1129–1148
Ui T (1983) Volcanic dry avalanche deposits—identification and comparison with nonvolcanic debris stream deposits. J Volcanol Geoth Res 18(1):135–150
Wadge G, Francis PW, Ramirez CF (1995) The Socompa collapse and avalanche event. J Volcanol Geotherm Res 66(1):309–336
Weidinger JT, Schramm JM, Surenian R (1996) On preparatory causal factors, initiating the prehistoric Tsergo Ri landslide (Langthang Himal, Nepal). Tectonophysics 260:95–107
Wyk V, de Vries B, Self S, Francis PW, Keszthelyi L (2001) A gravitational spreading origin for the Socompa debris avalanche. J Volcanol Geotherm Res 105(3):225–247
Zubovich AV, Mikolaichuk AV, Kalmetieva ZA, Mosienko OI (2009) Contemporary geodynamics of Nura M = 6.6 earthquake area (Pamir-Alai) In: Bulashevich YP (ed) Fifth Reading: Geodynamics, deep structure, heat field of Earth. Geophysical field interpretation (in Russian). Ekaterinburg
Acknowledgments
We thank Dr Kanatbek Abdrakhmatov, Kyrgyzstan Institute of Seismology, for his invaluable field knowledge and support; Ainagul, our cook and Kyrgyz translator; Muhtarbek our driver and minder; Dr Alexander Strom for his thoughtful discussions and the Kyrgyz nomad family who fed us in the field and educated us in Kyrgyz social customs. This research was funded by FRST contract CO5X0402 between GNS Science Ltd and University of Canterbury. Constructive reviews by Alexander Strom and an anonymous reviewer resulted in significant improvements to the original manuscript.
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Robinson, T.R., Davies, T.R.H., Reznichenko, N.V. et al. The extremely long-runout Komansu rock avalanche in the Trans Alai range, Pamir Mountains, southern Kyrgyzstan. Landslides 12, 523–535 (2015). https://doi.org/10.1007/s10346-014-0492-y
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DOI: https://doi.org/10.1007/s10346-014-0492-y