Regina sits on a deep sequence of glaciolacustrine clays and tills within the Bearpaw Formation—materials that amplify ground motion in ways generic NBCC values cannot capture. The city’s seismic hazard is modest but real, driven by intraplate events east of the Rockies. A site-specific seismic microzonation study maps the spatial variability of peak ground acceleration, spectral response, and soil fundamental period across a property. We integrate MASW surveys to measure Vs profiles down to 30 metres, then feed that data into 1D equivalent-linear site response models. The result is a set of design spectra that reflect actual stratigraphy—not just a conservative envelope. For engineers working under Part 4 of the National Building Code, this level of detail supports performance-based design and avoids overdesigning foundations or underrepresenting short-period amplification in soft clay.
A site class boundary can shift within a single lot on Regina's lake plain—microzonation catches that before the concrete does.
Local geotechnical context
Regina’s growth through the 20th century followed the rail lines and the flat prairie grid—not the subsurface. Many older commercial and institutional buildings were sited on what was convenient, not on what was geotechnically homogeneous. The risk today is that a uniform seismic design assumption applied to a variably thick clay deposit can produce two very different structural responses under the same ground motion. Short-period amplification in soft clay can increase spectral accelerations well above the NBCC’s default site class values, especially where the depth to till changes abruptly. We have seen this in post-construction reviews on the city’s east side, where clay thickness varies from 5 to 15 metres across a single block. A seismic microzonation study identifies these transitions before design locks in, allowing structural engineers to adjust base shear, drift limits, and detailing requirements per zone. Ignoring this step means the building code is being applied with incomplete site data—and the difference can show up as unexpected damage in a moderate event.
Common questions
What is the difference between a seismic hazard map and a microzonation study?
A seismic hazard map like Canada's national model provides uniform hazard spectra for reference rock conditions over a grid. A microzonation study takes that rock motion and propagates it through the actual soil column at your site, accounting for stratigraphy, Vs profile, and dynamic soil properties. The result is a site-specific spectrum that can differ significantly from the default NBCC site class values—especially in a city like Regina where clay thickness varies over short distances.
How is seismic microzonation used in structural design?
The design spectra from a microzonation study feed directly into the structural analysis. Rather than using the generic acceleration values from NBCC Table 4.1.8.4, the structural engineer applies the site-specific Sa(0.2s) and Sa(1.0s) values for each building zone. This supports more accurate base shear calculations, drift checks, and detailing under CSA A23.3, and can reduce unnecessary conservatism where soil conditions are more favourable than the default site class suggests.
What field methods do you use to measure shear-wave velocity in Regina?
Our primary tool is MASW (Multichannel Analysis of Surface Waves), which produces a continuous Vs profile down to 30 metres without drilling. On larger or more complex sites we supplement with downhole seismic testing in boreholes to verify the MASW results at depth. For sites with very soft near-surface clay, we may also run HVSR measurements to corroborate the fundamental site period. All testing follows ASTM D7400 and D4428.
What does a seismic microzonation study cost for a site in Regina?
Cost depends on site area, number of measurement points, and whether laboratory dynamic testing is included. For a typical commercial or institutional site in Regina, a complete microzonation study with MASW, site response modelling, and a design spectra report generally ranges from CA$5,130 to CA$21,750. We provide a fixed-fee proposal after reviewing your site plan and project requirements.
