Wavefield separation using a volume distribution of three component recordings

Abstract

By making multiple three component (3C) measurements around a volume so that the rate of change of the wavefield in all directions can be estimated, it is possible to calculate the divergence and the curl of the wavefield which in turns corresponds to P- and S-waves. The volume may be of arbitrary shape, but the equations for wavefield separation are simplified if the volume has a known shape such as that of a tetrahedron. The dimensions of the volume should be smaller than approximately one fifth of the minimum wavelength of the recorded wavefield. A field test was carried out in Oman in April 1998. With a lack of distinct P- and S-waves in the data, the technique was instead evaluated on the airwave-induced ground motion. The airwave arrival was found to consist mainly of vertical motion that decays with depth. The wavefield separation technique was successfully tested on this arrival. Copyright 1999 by the American Geophysical Union.