Seismic site amplification assessment in the Dakwäkäda (Haines Junction) area of Yukon, Canada, from probabilistic inference of passive seismic measurements

The Dakwäkäda (Haines Junction) area is in a tectonically active region of Yukon, Canada, with significant natural hazard potential. Despite this, little knowledge exists about local site properties, which influence earthquake shaking intensity and duration (site effects). This work constrains sediment properties to quantify these effects. Passive seismic recordings at 14 sites are used to extract dispersion measurements and probabilistically infer 1D subsurface shear-wave velocity ( V S ), including rigorous model uncertainty quantification. The V S models are used to classify sites according to proxies for site rigidity. Results, including uncertainties, are propagated into estimates of linear site amplification factors for earthquake ground motion determination. Our results indicate much of the area can be characterized by site class C and modest amplification potential. Spatial variability in our results is predominantly attributed to hydrologic and cryospheric processes. The presence of permafrost in the area may currently mitigate amplification of earthquake shaking. Our results point to the need to understand seasonal and long-term changes in site effects, particularly in response to permafrost thaw within the warming climate. Results from this work can contribute to strategic community planning that mitigates natural hazards in the Dakwäkäda area, and other seismically active areas throughout the global North.