Seismic response in Catania by different methodologies

Abstract

The prediction of the seismic response and assessment of the amplification factor of the surface soils is a topic of maximum interest in engineering seismology and the final goal of any microzonation study. Two very different numerical techniques are described in this paper. One is a 2-D method, the Spectral Element Method (SPEM-2D), which solves the propogation of the seismic field through complex geological structures. The other is a 1-D method (by the GEODIN code), commonly used in engineering practice, which takes into account the detailed shear waves soil profile or superficial layers, including soil non-linearity. The seismic response of the surface by 1-D code is evaluated, using as input motion at the conventional bedrock sealed recorded accelerograms and synthetic accelerograms given by the 2-D code at a given depth. A comparison between soil response at the surface, given by the 2-D method, and by the 1-D method is presented in the paper. In particular the effects of the seismic input, of the shear waves soil profile and of the soil non-linearity, are also analyzed and discussed.