Generating Density Models with Seismic Refraction Data

Abstract

Seismic refraction traveltime data can be inverted to obtain a depth model of the weathered layer in terms of the seismic velocities. Furthermore, the head wave amplitudes can be inverted to generate a model of the scaled density ratios in the near surface. These seismic refraction models of the near-surface can be used in two modes. The first is to derive a representative model of the in-situ rock densities in the sub-weathering. The second is to fully compensate for the weathered layer, in order to detect any prospective gravity anomalies originating in the sub-weathering. The extensive sets of seismic data recorded for regional investigations by Geoscience Australia are well suited to deriving detailed models of the depth of weathering and scaled density contrasts. These models can be usefully employed as starting models for model-based inversion of coincident gravity data.