Joint Inversion of Receiver Functions and Surface-Wave Dispersion for Crustal Structure

摘要

Teleseismic P-wave receiver functions and surface-wave dispersion measurements can be employed to simultaneously infer the shear-wave velocity distribution with depth in the lithosphere. Receiver functions are primarily sensitive to shear-wave velocity contrasts and vertical travel times and surface-wave dispersion measurements are sensitive to vertical shear-wave velocity averages, so that their combination bridges resolution gaps associated with each individual data set. The inversions are performed using a joint, linearized inversion scheme which accounts for the relative influence of each set of observations, and allows a trade-off between fitting the observations and the smoothness of the model. Additional constraints on mantle structure are also incorporated during the inversion procedure since requiring the data to blend smoothly into an appropriate deep structure affects the estimate of the lower crust velocities, yielding models which are more consistent with expectations than those resulting from unconstrained inversions. We have found that a priori knowledge of upper mantle velocities are required to predict the dispersion up to 50 sec period and that stability constraints are required. When dispersion is limited to periods grater than 15 sec a priori information on the upper crustal velocities may also be required. Results of applying this technique to data from different tectonic environments in the Arabian Plate and North America will be presented.