Rates and uncertainties on seismic moment and deformation in eastern Canada

Abstract

On the basis of earthquake statistics from the Canadian earthquake hazard model, we estimate the rates of seismic moment and deformation in seismic zones of eastern Canada. We use a logic tree approach to derive median values and 66% confidence intervals for models based on earthquake cluster distributions and geological and tectonic structures. Typical moment rates are low, (0.1–1) × 1017 N m yr−1, equivalent to a magnitude Mw = 7 earthquake every 350–3500 years in each seismic zone. In a few zones, such as Baffin Bay, moment rates reach (2–10) × 1017 N m yr−1. Expressed in terms of relative velocity between zone boundaries, seismic deformation rates are typically 0.2–0.5 mm yr−1. For a few regions of high seismicity, such as Baffin Bay, Charlevoix, or Grand Banks, the relative velocities reach 1–2 mm yr−1. Strain rates are typical of the intraplate environment (10−13–10−10 yr−1), with values locally as high as 10−8 yr−1. These rates give some insight into geodynamic aspects of the northeastern North America plate. Assuming that the seismic deformation rates represent long‐term deformation of the lithosphere, they provide some constraint to the amplitude and variability of intraplate strain. On a shorter timescale, seismic strain rates can be compared with postglacial rebound predictions and might help constrain some aspects of these models. Because they reflect the seismic energy released over the last few hundred years, our estimates, in combination with geodetic measurements, can also help constrain models of earthquake dynamics in eastern North America.