Maple Ridge grew along the Fraser River floodplain and pushed up onto the glacially overridden uplands of the Haney plateau, creating a patchwork of ground conditions that behave completely differently under earthquake shaking. In our work here, we see the direct consequence of this history: a project on the north side of Lougheed Highway can sit on dense till while one three blocks south rests on 30 meters of compressible alluvium. The National Building Code of Canada assigns a single seismic hazard value to the municipality, but site-specific seismic microzonation reveals the real story—amplification factors, fundamental period shifts, and liquefaction susceptibility that vary across short distances. We run these studies to give structural engineers ground motion parameters they can trust, not just code defaults that assume uniform soil conditions across a complex glacial-fluvial landscape.
A single NBCC hazard value cannot capture the threefold difference in short-period amplification we have measured between the bedrock uplands and the floodplain silts of Maple Ridge.
Scope of work
Area-specific notes
What we often notice in Maple Ridge is that the older commercial buildings along Dewdney Trunk Road were constructed before modern seismic detailing and, in many cases, without any deep foundation consideration for the soft soils underneath. When we run a one-dimensional site response analysis using DEEPSOIL or equivalent linear tools, the acceleration time histories at surface level show amplification in the 0.3–0.6 second range—right where many two- to three-storey structures have their fundamental period. That resonance effect can push inter-story drift well beyond what a code-level static analysis would predict. Liquefaction is not a theoretical concern here either. We have mapped loose saturated sands at depths where cyclic stress ratios exceed the cyclic resistance ratio under a 1-in-2,475-year event, particularly in the Port Haney area. A proper microzonation study identifies these zones explicitly so the structural design can incorporate Improvement, deep foundations, or both before the first shovel hits the ground. Skipping this step leaves a gap in the seismic load path that cannot be fixed with stronger beams alone.
Watch how it works
Standards used
NBCC 2020 (National Building Code of Canada, Part 4, Division B), CSA A23.3-19 (Design of concrete structures, seismic provisions), ASTM D4428/D4428M-14 (Crosshole seismic testing), ASTM D7400-19 (Downhole seismic testing), Boulanger & Idriss (2014) CPT-based liquefaction triggering procedure
Linked services
VS30 Profiling and Site Classification
Active and passive surface wave testing to measure shear wave velocity in the upper 30 m, classified per NBCC 2020 Table 4.1.8.4.A. We provide the measured VS30 and the corresponding site class for structural design input.
One-Dimensional Site Response Analysis (SHA)
Equivalent linear or nonlinear ground response modeling using input motions matched to the NBCC 2020 uniform hazard spectrum for Vancouver. Output includes surface acceleration time histories, response spectra, and amplification factors for short and long periods.
Liquefaction Hazard Mapping
CPT-based and SPT-based liquefaction triggering assessment following the Boulanger-Idriss (2014) framework. We calculate the factor of safety against liquefaction and estimate post-liquefaction settlement and lateral spreading displacement for the project footprint.
Typical parameters
Q&A
What is the typical cost range for a seismic microzonation study in Maple Ridge?
The cost for a site-specific microzonation study in Maple Ridge generally ranges from CA$5,820 to CA$24,420 depending on the number of measurement points, the depth of investigation, and whether CPT rigs or drilling equipment must be mobilized to access the site. A small lot with one MASW line and a single CPT sounding falls at the lower end, while a multi-hectare commercial development requiring several shear wave profiles, downhole testing, and a full site response analysis will be at the upper end.
How does NBCC 2020 handle site amplification in Maple Ridge?
NBCC 2020 provides tabulated amplification factors Fa and Fv based on site class and the intensity of shaking on reference rock. However, the code values are conservative averages. A site-specific microzonation study measures the actual shear wave velocity profile and runs a ground response analysis to calculate amplification factors that reflect the real stratigraphy, which often results in more accurate—and sometimes lower—design spectral accelerations than the tabulated defaults.
What ground conditions in Maple Ridge are most susceptible to liquefaction?
The loose, saturated sands and silty sands of the Fraser River floodplain deposits are the primary liquefiable units. We typically identify these in the upper 10 to 15 meters in areas south of the Lougheed Highway, particularly in the Albion and Port Haney flats. The combination of high groundwater (often within 2 meters of the surface) and poorly consolidated Holocene sediments creates the conditions where cyclic loading from a magnitude 7+ event can trigger excess pore pressure and strength loss.
How many measurement points are needed for a reliable microzonation map?
For a single building lot, one to two shear wave velocity profiles combined with a CPT or SPT sounding may suffice. For a subdivision or industrial park covering several hectares, we typically recommend a grid of measurement points at 50- to 100-meter spacing to capture lateral variability in the alluvial and glacial deposits. The density depends on how abruptly the subsurface changes—something we often see in Maple Ridge where till ridges and buried channels create sharp transitions over short distances.
Can seismic microzonation reduce foundation costs for a Maple Ridge project?
Yes. When the site-specific analysis shows stiffer conditions than the default code assumption—for example, where glacial till is within 30 meters of the surface—the design spectral accelerations often decrease. This can translate into lower seismic base shear demands and, in some cases, allows the structural engineer to avoid costly Improvement or deep foundation elements that would have been specified under a more conservative site class assumption.