A Characteristic-Period Based Approach for Evaluating Earthquake-Induced Displacements of the Large Büyükçekmece Landslide (Turkey)
The Büyükçekmece landslide is located in Turkey, W of Istanbul, about 15 km northward from the North Anatolian Fault Zone (NAFZ) and involves upper Oligocene to lower Miocene deposits, consisting of silty clays, tuffs and sands. No earthquake-induced re-activations are testified so far but due to the high seismicity of the area (struck by the 17th August 1999 Mw 7.4 Kocaeli and by the 12th November Mw 7.2 Düzce earthquakes) it was selected as the case-study in the framework of the European project “MARSite—Marmara Supersite: new directions in seismic hazard assessment through focused Earth observation in the Marmara Supersite”. Due to the existence of several secondary scarps, the original geological setting of the sedimentary deposits is significantly modified as many counter-slope-tilted landslide sub-masses can be identified in the landslide mass. Earthquake-induced displacements of the landslide were evaluated through a characteristic-period based (CPB) approach. To this aim, a stress-strain dynamic numerical modelling was carried out using several seismic inputs with Arias intensity (AI) values ranging from 1 and 0.01 m/s and characteristic periods, Tm, ranging from 0.3 to 16.5 s. Depending on the landslide dimensions (thickness and length), characteristic periods for thicknesses (Ts) and lengths (Tl), were computed to define the corresponding ratios over Tm. The obtained results indicate that the effective characteristic period of the landslide (Tl *) corresponds to the length of a single sub-mass, and not to the total length of the landslide. Moreover, for the lowest AI values the maximum earthquake-induced displacements correspond to Tm values close to resonance period of the landslide while for higher AI values, such a 2D interaction between landslide mass and seismic waves is much more evident.
KeywordsEarthquake-induced landslide Numerical modelling Turkey
Research carried out in the framework of the project “MARSite—Marmara Supersite: new directions in seismic hazard assessment through focused Earth observation in the Marmara Supersite” (WorkPackage6).
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