EFFECTS OF SURFACE AND SUBSURFACE TOPOGRAPHY ON STRONG GROUND MOTION AT THE CITY OF AEGION - GREECE

摘要

In this paper, the effect of surface and subsurface topography is studied along a characteristic crosssection of the Aegion City, Greece, which suffered many damaging earthquakes. This site has the unique feature of combining the good knowledge of local geology, topography and dynamic soil properties, with the existence of a permanent surface and downhole strong motion array that provided several earthquake recordings during the last 2 years. Theoretical approaches (1D, 2D) and analyses of experimental data have been applied at the site in order to reveal the time and frequency domain characteristics of ground motion at both upper and lower parts of the topographic relief. 1D site response analyses proved to be inadequate to simulate successfully the wave propagation pattern in the foothill part, where the down-hole array is, most probably due to complex effects related with the existence of locally generated and laterally propagated from the lateral discontinuities surface waves which are observed on the recordings and the 2D analyses. Both experimental data and theoretical analyses reveal the amplification of all seismic components near the crest and the complicated nature of the wave-field near the foothill.