Amplification of strong ground motion in the city of Zagreb, Croatia, estimated by computation of synthetic seismograms. Soil Dynamics and Earthquake Engineering

A hybrid technique consisting of modal summation and subsequent \uaenite differences modelling is applied for the computation of synthetic accelerograms along a pro\uaele crossing the city of Zagreb, the capital of Croatia. Assuming the source geometry is known, the ampli\uaecation properties of the underlying soil may be determined by comparison of synthetics and their response spectra computed for a bedrock model with the ones obtained under the assumption of a realistic laterally varying local model. The peak ground acceleration is larger by a factor of up to 3.5 than the value obtained for the bedrock model. The ampli\uaecation of the response spectra is most prominent for frequencies below 2 Hz, and increases sharply to the SW from the mapped fault running through the centre of the city. q 2002 Published by Elsevier Science Ltd