Spatiotemporal Seismic Risk Assessment of Wood-frame Houses in Victoria, Canada under M9 Megathrust Subduction Sequences

Abstract

This study assesses spatiotemporal seismic risk of a realistic portfolio of wood-frame houses in the City of Victoria, British Colombia, Canada, subjected to a M9 sequence of earthquakes originating from the Cascadia subduction zone in Pacific Northwest. Crustal aftershocks, triggered by the mega-thrust mainshock, may occur in much proximity to population and buildings, and different types of buildings may be affected due to different ground-motion characteristics. The developed time-dependent seismic risk model consists of an Epidemic Type Aftershock Sequence model, ground-motion model, and aftershock seismic fragility model. The seismic hazard model for synthetic mainshock-aftershock sequences is combined with the state-dependent fragility model to estimate time-dependent damage states of wood-frame houses. The output of the assessment is useful for making various risk management decisions more effectively.