Feasibility of determiningQof near‐surface materials from Rayleigh waves

Abstract

High-frequency (5–35 Hz) Rayleigh waves phase velocities can be inverted to shear (S)-wave velocities for a layered earth model up to 30 meters below ground surface in many settings (Xia et al., 1999 and Park et al., 1999). Given S-wave velocity, compressional (P)-wave velocity, and Rayleigh wave phase velocities, it is feasible to solve for P-wave quality factor QP and S-wave quality factor QS in the layered earth model by inverting Rayleigh wave attenuation coefficients. Model results demonstrate the plausibility of inverting QS from Rayleigh wave attenuation coefficients. Contributions to the Rayleigh wave attenuation coefficients from QP cannot be ignored when Vs/Vp reaches 0.45, which is not uncommon in near-surface settings. It is possible to invert QP from Rayleigh wave attenuation coefficients in some unconsolidated materials, which is a concept that differs from the common perception that Rayleigh wave attenuation coefficients are always far less sensitive to QP than to QS (Mitchell, 1975).