Rates and uncertainties on seismic moment and deformation in eastern Canada

Abstract

[1] 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) Â 10 17 N m yr À1 , equivalent to a magnitude M w = 7 earthquake every 350-3500 years in each seismic zone. In a few zones, such as Baffin Bay, moment rates reach (2-10) Â 10 17 N m yr À1 . Expressed in terms of relative velocity between zone boundaries, seismic deformation rates are typically 0.2-0.5 mm yr À1. For a few regions of high seismicity, such as Baffin Bay, Charlevoix, or Grand Banks, the relative velocities reach 1-2 mm yr À1 . Strain rates are typical of the intraplate environment (10 À13 -10 À10 yr À1 ), with values locally as high as 10 À8 yr À1 . 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.Citation: Mazzotti, S., and J. Adams (2005), Rates and uncertainties on seismic moment and deformation in eastern Canada,

GPS crustal strain, postglacial rebound, and seismic hazard in eastern North America: The Saint Lawrence valley example

“…The amplitude of this permanent seismic deformation can be estimated by assuming a magnitude recurrence distribution of the earthquakes and summing their moment up to a given maximum magnitude [e.g., Hyndman and Weichert , 1983]. On the basis of the statistics of a truncated Gutenberg‐Richter distribution, Mazzotti and Adams [2005] estimate that seismic strain rates in most of eastern Canada are about 10 −13 to 10 −11 yr −1 . Exceptions to these low strain rates can be found in the CSZ and LSZ.…”

Earthquake-triggered slumps (1935 Timiskaming M6.2) in Lake Kipawa, Western Quebec Seismic Zone, Canada

“…They are known to involve reactivation of Proterozoic structures such as failed rifts, now buried by younger Phanerozoic strata, as a consequence of ongoing plate movement and continued postglacial glacio-isostatic rebound (Kumarapeli, 1987;Wu, 1998;Mazzotti and Adams, 2005;Ma et al, 2008). Seismic risk analysis of intracratonic earthquakes is constrained by inadequate knowledge of seismic source zones, and lengthy recurrence intervals compared to the relatively brief duration of European settlement and short instrumental record (Basham and Adams, 1989;Johnson and Schweig, 1996;Stein and Mazzotti, 2007;Ma and Eaton, 2009).…”

Did the 6 April 2009 L'Aquila Earthquake Fill a Seismic Gap?

“…Unlike standard approaches (e.g., Anderson 1986;Mazzotti and Hyndman 2002;Mazzotti and Adams 2005), this method does not require the delineation of area or fault sources but implicitly incorporates them through the seismic catalog. More precisely, it consists of calculating moment rates M o for each cell of a homogeneous grid covering the entire study area (a homogeneous grid of 0.02° spacing in latitude and longitude is used in this application).…”