Mapping Seismic Hazard and Structural Reliability for Canadian Sites Considering Spatially Smoothed Seismicity Model

The estimated seismic hazard based on the delineated seismic source model is used as the basis to assign the seismic design loads in Canadian design codes such as in the National Building Code of Canada and the Canadian Highway Bridge Design Code. An alternative approach to estimate and map the seismic hazard is to use the seismicity model obtained based on the historical earthquake catalogue and spatial smoothing techniques. However, quantification of differences in the Canadian seismic hazard maps (CanSHMs) obtained based on the delineated seismic source model and smoothed seismic source model is unavailable. The quantification is valuable to identify epistemic uncertainty in the estimated seismic hazard and the degree of uncertainty in the mapped CanSHMs. In the present study, we develop seismic source models based on spatial smoothing and historical earthquake catalogue. We carry out systematic quantification of the differences in the estimated and mapped Canadian seismic hazard by considering the delineated source model and spatially smoothed source models. For the development of the spatially smoothed seismic source models, we consider both spatial kernel smoothing techniques with or without adaptive bandwidth. The results indicate that the use of the delineated seismic source model could lead to under or over-estimation of the seismic hazard as compared to those estimated based on spatially smoothed seismic source models. This suggests that an epistemic uncertainty caused by the seismic source model should be considered to estimate and map the seismic hazard, which can be done by expanding the logic tree that includes multiple seismic source models to evaluate the seismic hazard. Furthermore, the implication of using one or the other approach in mapping seismic hazard on structural reliability is investigated by using an equivalent nonlinear inelastic single-degree-of-freedom system.