Site response analysis models: Case study from sites near Algiers city

It is well known that local site conditions can play an important role in the amplification of ground motion in a given area. In fact, local geological and soil conditions shape the intensity of ground shaking and consequently influence earthquake damages. Namely, site conditions affect the amplitude, the frequency content and the duration of ground motion. Damages induced by site effects depend on the topographic irregularities, the characteristics of the input motion and the subsurface material proprieties. It is established that site effects should be considered as crucial input in the damage evaluation process and thus need accurate evaluation. Among different approaches used for modeling and analyzing site effect, the one-dimensional ground response analysis method is particularly flexible and can be applied easily as in this study to estimate site amplification under earthquake shaking. In this study, site effect is characterized by four main parameters, namely shear modulus, density, velocity of shear waves propagation and soil damping ratio. Then these parameters are input in the one–dimensional ground response analysis to estimate the transfer functions required to calculate the ground amplification. This study focuses on amplification peaks observed for similar frequency between earthquake and soil nature. The method used allows us to derive realistic results which can be used to improve local seismic hazard values.