Constraining Crustal Properties with Bayesian Joint Inversion of
Vertical and Radial Teleseismic P-wave Coda Autocorrelations
Mehdi Tork Qashqai
Deep Earth Imaging, Future Science Platform, The Commonwealth Scientific and Industrial Research Organization (CSIRO), Deep Earth Imaging, Future Science Platform, The Commonwealth Scientific and Industrial Research Organization (CSIRO), Deep Earth Imaging, Future Science Platform, The Commonwealth Scientific and Industrial Research Organization (CSIRO), Deep Earth Imaging, Future Science Platform, The Commonwealth Scientific and Industrial Research Organization (CSIRO)
Corresponding Author:[email protected]
Author ProfileAbstract
The sensitivity of seismic compressional and shear waves and their
velocity ratios to rock lithology, pore fluids, and high-temperature
materials makes these parameters very useful for constraining the
physical state of the crust. In this study, we develop a joint inversion
approach utilizing both radial and vertical components’ autocorrelations
of tele seismic P-wave coda for imaging the crust by simultaneously
characterizing the crustal Vp, Vs and Vp/Vs ratio. Autocorrelations of
the radial and vertical components contain P and S waves that are
reflected from the subsurface. Therefore, joint inversion of them can
account for the variations of both Vp and Vs, and consequently, the
Vp/Vs ratio. Synthetic inversions show significant improvement in the
estimation of these parameters com pared to those from the inversion of
either, receiver functions or the autocorrelation of the vertical
component. The velocity models inferred from the application of the
approach to teleseismic data recorded along a north-south passive
seismic profile (BILBY experiment) in central Australia reveal a
distinct pattern of the Moho and the Vp/Vs variations across the crustal
blocks/domain. The general trend of the Moho structure corresponds well
with the change of the reflectivity that can normally be seen at the
base of the crust and also with the Moho estimated from the previous
studies including the deep seismic reflection profiling method. The
Vp/Vs structure at depths greater than 10 km shows dominant high values
beneath locations where the crustal domains interact (e.g., at
transition from one domain to another).