A common oversight we encounter in St. Albert's expanding residential subdivisions is treating the entire city as a single seismic hazard zone. The reality is that localized variations in the glacial Lake Edmonton sediments, buried preglacial valley fills, and the near-surface sands along the Sturgeon River create dramatically different ground responses during an earthquake. A standard NBCC hazard value won't capture the amplification that occurs where soft clays thicken against the valley walls. We combine deep subsurface exploration via CPT testing with geophysical profiling to map these transitions, giving structural engineers the site-specific spectra they actually need to avoid costly under-design in the city’s west-end developments.
Ground amplification in St. Albert's buried valleys can easily double the surface shaking relative to bedrock, a detail that generic code values overlook.
