The ground beneath South Surrey tells a very different story from the soils in Whalley or Bridgeview. Near the Nicomekl River, you encounter deep organic silts and soft clays that amplify low-frequency shaking. Move north toward the uplands, and glacial till dominates—stiffer, but with its own resonance characteristics. A standard code-based spectrum cannot resolve these contrasts. Our seismic microzonation work maps shear wave velocity, predominant period, and site amplification across the project footprint, giving structural engineers the precise Site Class and hazard parameters demanded by NBCC 2020. For sites with marginal liquefaction indicators, we often pair seismic microzonation with a CPT program to constrain cyclic resistance ratios, and when thickness of soft fill is unknown we run test pits to log stratigraphy directly before deploying surface wave arrays.
A 0.1-second shift in site period can double the spectral acceleration demand on a mid-rise structure—Surrey’s soft delta soils make microzonation a non-negotiable step.
