Table of Contents

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

References






List of Tables



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



List of Figures



Links to Chapter 1 Figures

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




List of Appendixes



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