Abstract

The difference between polarization properties of surface waves and noise provides us with a simple way of discriminating the fundamental mode surface waves on three-component seismograms. In this process, vertical, radial and transverse component amplitudes at each frequency are weighted according to a theoretical three-dimensional particle motion pattern for a selected window length (WL) and moving interval (MI). For the epicentral distances closer than about 2200 km, the weighted functions of a formerly proposed approach are not compatible with the angular distributions of polarization properties of surface waves. It means that the former weighted functions are not perfectly able to weight surface waves amplitudes of some epicentral distances. In order to solve this problem, a modification in this study is implemented by analyzing compatibility of the weighted functions with the angular distribution of polarization properties of synthetic surface waves. The former and new processes are tested on three component synthetic seismograms and on some digital broadband records. As a result, the new filtering process (NFP) is shown to be more flexible and stable. It can be used to discriminate the fundamental mode Love and Rayleigh waves on three-component seismograms at all ranges of epicentral distances.

Key words: Former filtering process (FFP), surface wave particle motion discrimination process, new filtering process (NFP), modified surface wave particle motion discrimination process.