Application of Joint Receiver-Function Surface-Wave Dispersion for Local Structure in Eurasia
SAINT LOUIS UNIV MO
Pagination or Media Count:
Subsurface geology generally has a broad wave number spectrum containing sharp, or high wave-number, changes in velocity near major geologic boundaries and smooth low wave-number variations in regions of relatively uniform geologic structure. Access to the full spectrum of earth structure requires that we exploit signals that span a wide frequency range and that are sensitive to the entire spectrum of heterogeneity. Our research is targeted at improving resolution of the full range of earth heterogeneity by combining seismic data sets traditionally analyzed separately. We will present the results of our efforts to combine teleseismic P-wave receiver functions and surface-wave dispersion measurements in a joint inversion for the variation in shear-wave velocity with depth in the lithosphere. Receiver functions are primarily sensitive to shear-wave velocity contrasts and vertical travel times, whereas surface-wave dispersion measurements are sensitive to vertical shear-wave velocity averages. Their combination bridges resolution gaps associated with each individual data set. The data are inverted 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, constructing a smooth model, and matching a priori constraints. Receiver functions are readily calculated using P-waveforms from distant earthquakes, and waves arriving from different directions can provide information on lateral variations in earth structure. Intermediate- to long-period dispersion values are available from global and regional tomographic studies and can be supplemented at the shortest periods using direct measurements from recordings from nearby events when they are available.
- Seismic Detection and Detectors