Wessex Institute of Technology, University of Portsmouth, Ashurst Lodge, Ashurst, Southampton, UK, SO4 2AA
Abstract:
A numerical method is used for calculating the two-dimensional scattering of incident SH waves to try to explain some of the amplification patterns observed from recent data of the Mexico City's accelerometric array. The method is briefly presented and its efficiency is tested against analytical and other numerical solutions for canyons and alluvial valleys.
Spectral ratios computed for transition and lake-bed zones of the Mexico City valley with respect to the average motion at hill-zone sites are also presented. The one-dimensional model is used to explain the amplifications observed at a site where the valley is relatively shallow, while the two-dimensional approach is employed at another site at the centre of the valley where irregular amplification patterns have been observed. Results in the time domain are also shown.