Seismic site characterization via joint modeling of horizontal-to-vertical spectral ratios and surface wave dispersion : developing and validating a geophysical tool for deciphering Quaternary stratigraphic architecture of the Monahans dune field, West Texas.

Quaternary deposition for the Monahans dune system is reflected in its stratigraphic architecture through various periods of dune accretion, stabilization, and erosion as well as buried clay, carbonate-rich soils, and playa lake deposits. The complex and discontinuous stratigraphy of Monahans is difficult to capture without extensive borehole investigation. Shallow seismic techniques using Horizontal-to-Vertical Spectral Ratios (HVSR) and surface wave dispersion offer a cost-effective alternative to deciphering Quaternary architecture, but inverse models are subject to ambiguity and nonuniqueness. We jointly model HVSR and surface wave phase velocity dispersion measurements via global optimization to produce best-fit 1D shear wave velocity models for the interpretation of geologic structure and use statistical tools, including posterior probability distributions and parameter correlations, to demonstrate that joint modeling has the potential to impose stronger constraints on model parameters than modeling either seismic dataset alone.