Development of Deep Shear Wave Velocity Profiles with Estimates of Uncertainty in the Complex Interbedded Geology of Christchurch, New Zealand

Deep (+500-m) shear wave velocity (VS) profiles were developed at 14 sites throughout Christchurch, New Zealand, using a combination of active- and passive-source surface wave testing. The geology of Christchurch is complex and presents several challenges for surface wave testing. Specifically, the complex interlayering of relatively stiff gravels with soft sands, silts, and clays makes (1) the interpretation of experimental dispersion data ambiguous and (2) complicates the determination of appropriate inversion-layering parameterizations. In order to address the first issue, dispersion data uncertainty was quantified and several mode interpretations were considered during inversion. To address the second issue, 155 geotechnical boreholes and 199 geologic well logs in the vicinity of the test sites were used to guide the choice of layering parameterizations such that geologically realistic VS profiles were obtained via surface wave inversion. At each site, a suite of 1,000 VS profiles representing the combined effects of epistemic uncertainty and apparent aleatory variability in VS was obtained. These VS profiles are available on the DesignSafe-CI web site (https://doi.org/10.17603/DS21D4D) and are intended to aid in future seismic site response analyses.