This dataset of the elevation of basement and thickness of sediment above the syn- and post-rift unconformity (sediments above being generally Late Cretaceous and younger) was constructed for application to site response models in earthquake hazard analyses. Sediment thickness in meters is provided in zipped csv format on a 0.01-degree grid, and sediment thickness and basement elevation in meters relative to mean sea level are provided in GeoTIFF format on a 1-km grid.