Landslide processes and the stress field of the Earth's crust according to data on earthquake source mechanisms (on the example of the Tien Shan)
Category: 15-2
UDC 551/550
Z.A. Kalmetyeva(1), B.D. Moldobekov(1), I.A.Torgoev(2), I.I.Volkhin(3)
(1) Central-Asian Institute for Applied Geosciences, Bishkek, Kyrgyzstan
(2) Engineering Center “GEOPRIBOR” NAS KR, Bishkek, Kyrgyzstan
(3) Kyrgyz-Russian Slavic University, Bishkek, Kyrgyzstan
Abstract. Comparative analysis of spatial-temporal distribution of background earthquakes (М³2) and landslides was carried out in two earthquake and landslide-active areas in Kyrgyzstan: the Northern Tien Shan (mountains surrounding of the Chu valley) and the Western Tien Shan (northeast surrounding of the Fergana valley). Data on the active faults, regimes of modern tectonic movements and earthquake source mechanisms were analyzed to estimate the geodynamic conditions of the studied area. Atmospheric precipitations data were also taken into consideration.
The findings allow us to assume that landslide activity is an independent deformation process of a certain scale.
It was established that the locations of major landslides and dense clusters of background earthquake epicenters do not coincide; landslide locations are mostly determined by deep structure of the crust and are confined to the edges of the principal structure of the modern crustal uplift; the activation of the background seismicity and landslides occurs synchronously when the direction of the compression axis suddenly deviates from the horizontal.
Dependence of landslide activity on the amount of atmospheric precipitations is obvious. However, this factor should be considered rather as a condition for decreasing slope stability rather than the cause of landslide processes.
Keywords: landslides, earthquakes, earthquake source mechanism, compression axis, active faults, regime of the modern movements, precipitations.
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