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See detailA Review of Recent Case Studies of Landslides Investigated in the Tien Shan Using Microseismic and Other Geophysical Methods
Torgoev, Almazbek ULg; Lamair, Laura ULg; Torgoev et al

in Ugai, K; Wakai, A; Yagi, H (Eds.) Proceedings of the International Symposium on Earthquake-induced landslides (2012, December)

This paper reviews recent case studies completed on landslides (and dams) with probable (post-) seismic origin or susceptible to seismic failure in the Tien Shan, Central Asia. The first investigation ... [more ▼]

This paper reviews recent case studies completed on landslides (and dams) with probable (post-) seismic origin or susceptible to seismic failure in the Tien Shan, Central Asia. The first investigation presented here was carried out in 2005 on the Kainama earthflow, mainly composed of loess, which occurred in April 2004 and killed 33 people. Geophysical and seismological were used to build a reliable 3D model of the geometry and properties of the subsurface layers. The paper will also present results from microseismic measurements on loess landslides in Tajikistan that partly have a seismic origin. They are located close to the area that was affected in 1949 by the M=7.4 Khait earthquake and the numerous landslides triggered during the event, including the Khait rock avalanche. [less ▲]

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See detailEvidence of a changing size-frequency distribution of landslides in the Kyrgyz Tien Shan, Central Asia
Schlögel, Romy; Torgoev; De Marneffe, Cédric et al

in Earth Surface Processes & Landforms (2011), 36/12

There is a strong possibility that environmental change (whether climate or land use) will be manifest as changes in the size–frequency distribution of landslides. Here, evidence is presented for this ... [more ▼]

There is a strong possibility that environmental change (whether climate or land use) will be manifest as changes in the size–frequency distribution of landslides. Here, evidence is presented for this from western Kyrgyzstan, Central Asia. Remote sensing and spatial analysis have been applied to map mass movements in the central part of the Maily‐Say Valley and to detect recent landslide activations. The evolution of landslide activity over the past 50 years has been analysed on the basis of pre‐existing landslide maps and new analyses of aerial photographs as well as Quickbird images. Five inventories were produced for the years 1962 (based on the existing map of 1962 and aerial photographs of 1962), 1984 (based on the existing map of 1977 and aerial photographs of 1984), 1996 (based on aerial photographs of 1996), 2002 (based on the existing map of 2003 and Quickbird imagery of 2002) and 2007 (based on Quickbird imagery of 2007). The geomorphologic features contained in the catalogues represent the landslide bodies observed from remote imagery of the corresponding year. Mapped landslides are generally considered as the result of a series of slope failure events. Size–frequency analyses applied to the five landslide inventories show that both the number and size of unstable slopes increased from 1962 (162 objects) to 2007 (208 objects) and the power‐law exponent decreased over time. This changing power‐law exponent may indicate that landslide‐related hazards are increasing. This tendency is documented in more detail for two active landslide zones, one in the main valley and one located to the west of it. Landslide detection methods were used to assist the evolution of slope instabilities. Choosing appropriate thresholds, the image subtraction method based on normalized difference vegetation index (NDVI) allowed accurate detection of new sliding activation in these two zones. This confirmed the results of the more extensive survey that there is a systematic shift in power law exponents and size–frequency distributions for Central Asian landslides. [less ▲]

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