S-wave velocity and statics from ground-roll inversion

Abstract

We are interested in the near surface for many reasons including the need to see through it to resolve geology and resources at depth. The near-surface often consists of unconsolidated, low-velocity material which can cause time delays in passing seismic waves, especially S-waves. Hence, it is necessary to obtain a detailed near-surface S-wave velocity structure to correct for these delays. Multichannel analysis of surface waves (MASW) (Park et al., 1998 and 1999; Xia et al., 1999) is an effective and increasingly popular method to obtain a near-surface S-wave velocity. MASW uses Rayleigh waves (or ground roll) to create dispersion curves (phase velocity versus frequency plots). Then, the inversion of these dispersion curves for the fundamental mode provides the near-surface S-wave velocity. These velocities can be used to infer the S-wave receiver statics.