Abstract

A 3D model of the geologic structure and associated seismic velocities in the Canterbury, New Zealand, region is developed utilizing data from depth‐converted seismic reflection lines, petroleum and water‐well logs, and cone penetration tests and is implicitly guided by existing contour maps and geologic cross sections in data‐sparse subregions. The model, developed using geostatistical Kriging, explicitly represents the significant and regionally recognizable geologic surfaces that mark the boundaries between geologic units with distinct lithology and age. The model is examined in the form of both geologic surface elevation contour maps as well as vertical cross sections of shear‐wave velocity, with the most prominent features being the Banks Peninsula Miocene–Pliocene volcanic edifice and the Pegasus and Rakaia late Mesozoic–Neogene sedimentary basins. The adequacy of the modeled geologic surfaces is assessed through a residual analysis of point constraints used in the Kriging and qualitative comparisons with previous geologic models of subsets of the region. Seismic velocities for the lithological units between the geologic surfaces have also been derived, thus providing the necessary information for a Canterbury velocity model for use in broadband seismic‐wave propagation. The developed model also has application for the determination of depths to specified shear‐wave velocities for use in empirical ground‐motion modeling, which is explicitly discussed via an example.

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