PROBABILITIES OF SIGNIFICANT EARTHQUAKE SHAKING IN COMMUNITIES ACROSS CANADA

Seismic hazard in Canada is well studied and extensively discussed within scientific and engineering communities. However, much of this information is presented in forums not readily accessible by those outside these communities, and in formats not easily understood by the “non-engineering” community. To address this, earthquake shaking probabilities were calculated for over 600 communities across Canada at each of three intensity levels (MMI V – widely-felt; MMI VI – threshold for non-structural damage; and, MMI VII – threshold of structural damage) and over 10, 50, and 100 year periods. This paper presents a subset of these calculations for 25 communities. While the dominant tectonic features affecting seismicity in western Canada are the Cascadia Subduction Zone and the Queen Charlotte Strike-Slip Fault Zone along the active western margin of the North America Plate, the most active seismic zone in eastern Canada is the Charlevoix-Kamouraska seismic zone of paleo-rift faults along the St. Lawrence River. Shaking probabilities for all earthquakes are based on the probabilistic seismic hazard models developed by the Geological Survey of Canada and adopted in the National Building Code of Canada. Results presented in this paper are intended to enable officials and the public to better identify and understand the earthquake threat in their communities. This information is offered to encourage and facilitate informed discussion on earthquake threat in Canada, and enable reasoned, defendable seismic funding decisions.