Article (Scientific journals)
Geophysical investigation and numerical modelling of unstable slopes: case-study of Kainama (Kyrgyzstan)
Danneels, Gaëlle; Bourdeau, Céline; Torgoev, I. et al.
2008In Geophysical Journal International, 175, p. 17-34
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Keywords :
electrical tomography; ambient noise; landslides
Abstract :
[en] The presence of massive Quaternary loess units at the eastern border of the Fergana Basin (Kyrgyzstan, Central Asia) makes this area particularly prone to the development of catastrophic loess earthflows, causing damages and injuries almost every year. Efficient disaster management requires a good understanding of the main causes of these mass movements, that is, increased groundwater pressure and seismic shaking. This paper focuses on the Kainama earthflow, mainly composed of loess, which occurred in 2004 April. Its high velocity and the long run-out zone caused the destruction of 12 houses and the death of 33 people. In summer 2005, a field survey consisting of geophysical and seismological measurements was carried out along the adjacent slope. By combination and geostatistical analysis of these data, a reliable 3-D model of the geometry and properties of the subsurface layers, as shown in the first part of the paper, was created. The analysis of the seismological data allowed us to point out a correlation between the thickness of the loess cover and the measured resonance frequencies and associated amplification potential. The second part of this paper is focused on the study of the seismic response of the slope by numerical simulations, using a 2-D finite difference code named FLAC.Modelling of the seismic amplification potential along the slope confirmed the results obtained from the seismological survey—strong amplifications at the crest and bottom of the slope where there is a thick loess cover and almost no amplification in the middle part of the slope. Furthermore, dynamic slope stability analyses were conducted to assess the influence of local amplifications and increased groundwater pressures on the slope failure. The results of the dynamic modelling, although preliminary, show that a combination of seismic and hydrologic origin (pore pressure build-up during the seismic shaking) is the most probable scenario responsible for the 2004 failure.
Disciplines :
Earth sciences & physical geography
Author, co-author :
Danneels, Gaëlle ;  Université de Liège - ULiège > Département Argenco : Secteur GeMMe > Géoressources minérales & Imagerie géologique
Bourdeau, Céline ;  Université de Liège - ULiège > Département de géologie > Géologie de l'environnement
Torgoev, I.
Havenith, Hans-Balder  ;  Université de Liège - ULiège > Département de géologie > Géologie de l'environnement
Language :
English
Title :
Geophysical investigation and numerical modelling of unstable slopes: case-study of Kainama (Kyrgyzstan)
Publication date :
2008
Journal title :
Geophysical Journal International
ISSN :
0956-540X
Publisher :
Blackwell Publishing
Volume :
175
Pages :
17-34
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 29 October 2009

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