The geophone array goes in at a 2-meter spacing, right across the glacial till that blankets most of Richmond Hill. We run the active MASW line first, then switch to passive arrays for deeper shear-wave velocity profiles. The Oak Ridges Moraine gives us a lot of variability here — stiff diamict at 6 meters in some areas, then 20 meters of sand and silt just a few blocks away. MASW surface wave testing provides the VS30 we need for NBCC site classification, and when the till is too thin to trust the average, we go deeper with seismic refraction to map bedrock topography beneath the overburden. What we deliver is not a generic hazard map — it is a block-by-block ground response model tied to actual borehole stratigraphy and shear-wave measurements collected on your site.
Richmond Hill sits on the Oak Ridges Moraine — site amplification here varies block by block, and a single VS30 value rarely tells the full story.
