The National Building Code of Canada (NBCC 2020) sets clear requirements for site classification based on vs30/" data-interlink="1">shear wave velocity, and in Brandon Manitoba the glacial till sequence overlying Cretaceous shale can vary significantly in stiffness and depth. We apply seismic tomography to resolve this vertical and lateral variability with continuous velocity profiles. The method works well here because the contrast between compact till and weathered bedrock is usually sharp enough to produce clear refracted arrivals. When we need additional confirmation of layer geometry we pair the survey with a resistivity survey which helps distinguish saturated sand pockets from clay lenses that might otherwise look similar on travel-time curves.
In Brandon Manitoba the contrast between compact till and weathered Cretaceous shale produces clear refracted arrivals, but fractured zones require reflection processing to resolve the interface correctly.