Joint probabilistic inversion of teleseismic body-wave autocorrelations: a new approach to constrain the crustal structure

Abstract:

It has been known for decades that the zero-offset body-wave reflection response of the Earth’s layers can be estimated from the autocorrelation of the seismic data associated with a source at depth (Claerbout, 1968). Unlike the P-to-S receiver functions which mainly contains S-wave information (the P-wave reflections have been removed by the deconvolution process), autocorrelations of teleseismic P-wave coda recorded on radial and vertical components contain P and S wave information associated with crustal layers. Therefore, radial and vertical components’ autocorrelations can provide additional constraints on the P and S wave velocities (V_p and V_s), and consequently the V_p/V_s ratio of crustal layers, if they are jointly inverted. In this study, we demonstrate the feasibility of this joint inversion to better constrain the crustal properties, especially the V_p/V_s ratio. Synthetic inversion tests show that the joint inversion of radial and vertical autocorrelations provides better estimates of crustal properties compared to the previously established inversions of radial receiver functions and the vertical component autocorrelation. The velocity and V_p/V_s models derived from the joint inversion of autocorrelations of teleseismic data recorded on a series of broadband seismic stations along a north-south profile in central Australia reveal clear separations of crustal blocks. The Moho structure inferred from the method correlates with the general trend of the Moho reflectivity pattern derived from the deep seismic reflection sections.