Abstract

The importance of 2D or 3D site effects has been shown by theoretical studies. However, there is a lack of observational evidence of site effects due to lateral heterogeneities. We have evaluated 1D and 2D site effects in the data obtained by a dense seismograph array that operated for more than 2 months in the alluvial basin of Parkway, New Zealand. 1D site effects were evaluated using three independent techniques: spectral ratios relative to a reference station, spectral ratios of horizontal relative to vertical ground motion, and a generalized inversion scheme. Site effects due to lateral heterogeneity were investigated in detail for two events using frequency-wavenumber analysis. Our results show that it is not possible to separate 1D from 2D site effects using frequency-domain techniques. This explains the scatter obtained from standard 1D data analysis: the 1D resonance peaks will be more or less contaminated with laterally propagating waves for different events.

First Page Preview

First page PDF preview
You do not currently have access to this article.