Site‐to‐bedrock over 1D transfer function ratio: An indicator of the proportion of edge‐generated surface waves?

Authors:
Publisher website
Google Scholar
Abstract
We study multi‐dimensional site effects in the small‐size deep sediment filled basin of Grenoble (French Alps). A very dense array composed of 3‐component seismometers over a 1 km aperture is used to investigate propagation parameters of waves propagating across the array. We present results for 6 teleseismic events for which we had a reference rock site. For the frequency range 0.1 to 1 Hz, records are clearly dominated by edge‐generated surface waves. Quantification of energy carried by each identified wave train allows interpreting the difference between site‐to‐bedrock and 1D transfer function estimates in terms of laterally propagating basin‐edge induced waves only above the fundamental resonance frequency of the basin. A simple ratio between site‐to‐bedrock and 1D transfer function curves should thus provide an estimation of the relative contribution of 1D and 2D/3D effects in ground motion on the condition that all the time signal length is taken into account.