LAUSR

Abstract The seismic stability of slopes and earthquake induced displacements should be evaluated with particular emphasis on earthquake records with site specific geological and geotechnical setting. The right lateral strike slip North Anatolian Fault (NAF) caused considerable damage on environment and residential areas of northern Turkey during the devastating 17.08.1999 Marmara and 12.11.Duzce earthquakes. Several mass movements have occurred around Karamursel, Oluklu, Ihsaniye, Hayriye and Yalakdere towns of Kocaeli within weathered/completely weathered Upper Cretaceous aged flysch, Eocene aged flysch and Pliocene soil deposits. A total of 38 instabilities were encountered and classified during the field studies. Geotechnical data were compiled from previous work and trial pits. Pseudostatic slope stability analysis were conducted along the identical slopes selected from the geological units. Peak ground acceleration values were picked up from stations, located around the study area. The static factor of safety values were calculated for slopes for each lithological unit. The critical acceleration values to cause seismic displacement were extracted from pseudostatic analyses. Variation of seismic displacements based on different amplitudes of a single scenario earthquake was calculated by double integration. Earthquake triggered seismic displacements could reach up to 46 cm based on the such scenario earthquake record of Marmara earthquake. Failed slopes and quiescent slopes might be triggered by an earthquake. This must be considered during land use planning for any single residence or agricultural purposes.