Title page
Acceptance form
Abstract
Résumé
Acknowledgments
Original Contribution
Table of Contents
List of Tables
List of Figures
List of Appendixes
Chapter 1
The Charlevoix Seismic Zone: overview of the earthquake activity and the geological environment
Chapter 2
Thermal and rheological constraints on the spatial distribution of CSZ
earthquakes
Chapter 3
Geological faults in the CSZ and their correlation with earthquakes
Chapter 4
Seismicity patterns from focal mechanisms, earthquake clusters,
multiplet analysis, and the search for surface fault ruptures
Chapter 5
Determination of the CSZ velocity structure from local earthquake data
Chapter 6
Summary and discussion
Table 1.1 Estimated first year of complete reporting of magnitude levels in the CSZ
Table 1.2 Number and yearly rate of located CSZ events by magnitude range
Table 2.1 Creep parameters of rocks used in this study
Table 2.2: Thickness and thermal parameters of crustal layers in the Charlevoix
region
Table 3.1: Rock Densities
Table 3.2 Seismic profiles of the CSZ
Table 3.3 Fault dimensions for stable continental earthquakes
Table 4.1 Factors defining the nature of the potential ruptures
Table 4.2 Rating scheme of the focal mechanism
Table 4.3: Focal mechanisms of earthquakes of magnitude 3.0 and larger
Table 4.4: Focal mechanisms of earthquakes recorded during the 1996 summer field
survey
Table 4.5 Other mechanisms. (1974; 1979 + events near La Malbaie)
Table 4.6 Statistics of the various sub-zones
Table 4.7 Aftershocks of the 19971028 event
Table 5.1: Station corrections to be used with the standard velocity model
Table 5.2 Velocities used to model the north and the south shore
Table 5.3 Range of P-wave velocities used in the 2-D velocity analysis
Table 5.4 Velocity model that minimizes the RMS
Table 5.5 Velocity model for the Laurentides Park region
Figure 1.1 Earthquakes in eastern Canada.
Figure 1.2 Boundaries of the Charlevoix Seismic Zone (CSZ)
Figure 1.3 Elevation in meters and earthquake hypocentres of the CSZ
Figure 1.4 CSZ hypocentres of the period October 1977 to May 1983
Figure 1.5 Topography of the CSZ with elevation in meters.
Figure 1.6 Scenes of the Charlevoix Seismic Zone.
Figure 1.7 Main geological features of the CSZ
Figure 1.8 Time-history of the Charlevoix network between 1970 and 1998
Figure 1.9 Location of the permanent seismograph stations in the CSZ
Figure 1.10 Examples of how arrival times have been picked over the years
Figure 1.11 Regional stations surrounding the CSZ
Figure 1.12 Seismograph stations in the CSZ
Figure 1.13 Correlation between mN and ML magnitudes
Figure 1.14 Distribution of located earthquakes for the period October 1977 -
December 1997
Figure 1.15 Number of events for various magnitude thresholds
Figure 1.16 Sub-zones around earthquake clusters with similar depth distribution
Figure 1.17 Time-history of the activity of the various sub-zones of Figure 1.16
Figure 1.18 A 30 day histogram of located earthquakes in the CSZ
Figure 1.19 Magnitude-recurrence curves for the CSZ
Figure 1.20 Focal depth distribution of the Charlevoix earthquakes for the period
October 1977 - December 1997
Figure 1.21 CSZ hypocentres and stations
Figure 1.22 CSZ hypocentres
Figure 1.23 Hypocentres by magnitude ranges
Figure 1.24 Lower hemisphere focal mechanisms in the CSZ
Links to Chapter 2 Figures
Figure 2.1 Focal depth distribution of the Charlevoix earthquakes for the period
October 1977 to December 1997
Figure 2.2 Sketch representing the various factors intervening in fault reactivation
Figure 2.3 Distribution of inferred maximum stress differences
Figure 2.4 Distribution of heat flow measurements in the Grenville Province
Figure 2.5 Computed geotherms for the Grenville region
Figure 2.6 Geotherms calculated with a surface heat flow of 60 mW/m
Figure 2.7 Crustal strength as a function of depth
Figure 2.8 Crustal strength as a function of depth
Figure 2.9 Stress difference (MPa) necessary to reactivate a fault located at a depth of
20 km
Figure 2.10 Map of the relation between pore-fluid pressure, coefficient of friction and
reactivation angle
Figure 2.11 Example of the impact of a change in fracture type for the rheological
profile
Figure 2.12 Synoptic model of the factors controlling the earthquake occurrences in the
CSZ
Links to Chapter 3 Figures
Figure 3.1 Location map of the CSZ surroundings and geographic entities mentioned
in the text
Figure 3.2 Principle of the side-looking radar system
Figure 3.3 Remote sensing radar images of the CSZ
Figure 3.4 CSZ total magnetic field
Figure 3.5 Solutions of the Euler deconvolution (N=0) of the magnetic field
Figure 3.6 Photos taken during the August 1994 gravity survey
Figure 3.7 Gravity and density data
Figure 3.8 Location map of the SOQUIP seismic reflection lines in the CSZ
Figure 3.9 Euler solutions of the magnetic field in the Quebec City region
Figure 3.10 Location of the four geophysical profiles discussed in text
Figure 3.11 Geophysical profile near Ile-aux-Coudres
Figure 3.12 Crater profile
Figure 3.13 Line 13 profile
Figure 3.14 Ile-aux-Lièvres profile
Figure 3.15 The three main sub-regions discussed in text
Figure 3.16 Interpreted structures of the CSZ
Figure 3.17 Major faults of the CSZ
Figure 3.18 SOQUIP seismic line 22
Figure 3.19 SOQUIP seismic line A
Figure 3.20 Geological faults and CSZ hypocentres
Figure 3.21 Cross-section across the 1979 M5 earthquake zone
Links to Chapter 4 Figures
Figure 4.1 Schematic cross-section of the type of rupture expected in the CSZ
Figure 4.2 Example of a seismic section (SOQUIP line 22)
Figure 4.3 Location map of the seismic lines acquired by SOQUIP and by their
partners
Figure 4.4 Seismic profiles that show the Quaternary sequence
Figure 4.5 Lower hemisphere focal mechanisms of the 12 quality A and B focal
mechanisms for events of magnitude mN 3.0
Figure 4.6. Focal mechanisms of the 8 quality A and B focal mechanisms for 1996
summer events
Figure 4.7 The two well-constrained focal mechanisms for the 1974 field survey
Figure 4.8 Focal mechanisms of the 1979 mN 5.0 earthquake
Figure 4.9 Revised focal mechanisms of Figure 1.26
Figure 4.10 Focal mechanisms of quality "A" and "B"
Figure 4.11 Results from the quality "A" and "B" of Figure 4.8
Figure 4.12 Method of defining earthquake groups
Figure 4.13 Hypocentre groups with 10 events or more
Figure 4.14 Cross-sections across the largest group of hypocentres
Figure 4.15 Earthquake groups (1.5 km distance) with a focal mechanism
Figure 4.16 Traces of a nine-tuplet (earthquake swarm)
Figure 4.17 Characteristics of the events of multiplets
Figure 4.18 CSZ Multiplets of the period November 1988 to August 1997
Figure 4.19 Earthquake hypocentres and sub-zones
Figure 4.20 Focal depth distribution for the various sub-zones
Figure 4.21 Hypocentres of the A61 sub-zone
Figure 4.22 Compared depth distributions
Figure 4.23 Vertical seismic traces of three quarry blasts
Figure 4.24 Airborne Synthetic Aperture Radar (SAR) image of the A61 Sub-zone
Figure 4.25 The 19971028 aftershock sequence
Figure 4.26 Hypocentres of the DNE sub-zone
Links to Chapter 5 Figures
Figure 5.1 P-wave velocity models of the Charlevoix and the Saguenay regions
Figure 5.2 Absolute time differences between the Pg and Sg arrivals
Figure 5.3 Characteristics of the events selected for the velocity inversion
Figure 5.4 Wadati plot for the events selected
Figure 5.5 RMS values for various combinations of Vp and Vs
Figure 5.6 Residuals for the various CSZ stations
Figure 5.7 RMS values, as in Figure 5.5
Figure 5.8 P-wave residuals
Figure 5.9 Best RMS obtained as a function of P-wave velocity
Figure 5.10 Number of residuals grouped in 0.05 s classes for the CSZ stations
Figure 5.11 Shifts between original event locations (X = Y = 0) and locations computed
with the best layered model
Figure 5.12 Epicentral map showing shift between original (yellow) and the relocated
(red) epicentres
Figure 5.13 CSZ events recorded at station DAQ
Figure 5.14 Wadati plot for the CSZ events recorded on DAQ
Figure 5.15 Vp-Vs tests for the DAQ data with RMS values in seconds
Figure 5.16 Best RMS for DAQ data obtained for given P-wave velocities and depth of
layers
Figure 5.17 Number of DAQ residuals for P and S waves grouped by 0.05 s classes
Figure 5.18 Distribution of the P and S residuals
Figure 5.19 Wadati plot for CSZ events recorded on DAQ
Figure 5.20 RMS calculated for crustal P and S velocities with CSZ events
Figure 5.21 Best RMS values at given depth and P velocities
Figure 5.22 P and S residuals computed with the best layered velocity model
Figure 5.23 Comparison of the computed 1-D velocity models with other models of the
Charlevoix and Saguenay regions
Links to Chapter 6 Figures
Figure 6.1 Mohr diagram representing relationship between stresses and failure
parameters
Figure 6.2 Factors that can lead to earthquakes in the CSZ
Figure 6.3 Schematic model of the CSZ earthquakes
Appendix 1
Example of a focal mechanism calculation and plots
Appendix 2
List of earthquake multiplets by sub-zone
Appendix 3
Recommendations for future monitoring of the CSZ