Geotechnical site conditions that can be very different due to changes in thickness and properties of soil layers, depth of bedrock and water table are among the main factors controlling earthquake characteristics on the ground surface. Soil layers subjected to cyclic stresses may lead to degradation of stress-strain and shear strength properties. The laboratory tests were conducted to evaluate the changes in the stress-strain and shear strength characteristics in terms of threshold cyclic shear stresses and cyclic yield stress. The effects of local site conditions are assessed based on geotechnical site conditions and earthquake source characteristics. (C) 2001 Published by Elsevier Science Ltd.