FOURTH-GENERATION SEISMIC HAZARD MAPS FOR THE 2005NATIONAL BUILDING CODE OF CANADA

摘要

The Geological Survey of Canada's new seismic hazard model for Canada will form the basis for the seismicdesign provisions of the 2005 National Building Code of Canada (NBCC). As such it represents Canada'sfourth generation of seismic hazard maps (previous ones were in 1953, 1970, and 1985). TheCornell-McGuire method is used with two complete earthquake source models - historical andregional/geological - to represent the uncertainty in where (and why) earthquakes will happen in the future.Ground motions for a deterministic Cascadia subduction earthquake are computed for southwestern Canada,and probabilistic seismic hazard for the nearly aseismic central part of Canada is assessed based on a globalmodel. A 'robust' method is used to combine the probabilistic hazard estimates (at a probability of 2%/50years or 0.000404 p.a.) from the four source models: the mapped value is the largest of the values. Productswill include seismic hazard maps, tabulated values, uniform hazard spectra (UHS), plots of deaggregatedhazard and documentation. For the seismic provisions of the 2005 National Building Code of Canada themedian ground motion on firm soil sites for spectral acceleration at periods of 0.2, 0.5, 1.0 and 2.0 secondsand peak acceleration will be used. The four spectral parameters will allow the construction of approximateUHS for each locality, and hence improve earthquake-resistant design.