Lamontagne, M. et Graham, D. 1994. A GIS and Remote Sensing Analysis of the Charlevoix Seismic Zone, Quebec, Canada, American Geophysical Union (AGU) meeting, Baltimore, May 1994.
Located some 150 km downstream from Quebec City, the Charlevoix seismic zone is the most seismically active area of Eastern Canada. Five earthquakes in the magnitude 6-7 range have occurred there in historical times. In addition, continuous micro-earthquake activity is recorded (about 1500 events of magnitude -0.5 to 5.0 since 1977). This analysis examines possible correlations between the micro-earthquakes and lineaments evidenced in remotely sensed data such as LANDSAT TM, Airborne Synthetic Aperture Radar (SAR) and the aeromagnetic field. In addition, bathymetric, gravimetric, topographic and shock metamorphism data are integrated into a Geographic Information System (GIS) database.
GIS tools allow earthquake epicentre concentrations to be emphasized. The clusters of enhanced activity show various linear trends, with a major one along the axis of the St. Lawrence River. Three main sub-areas separated by aseismic regions exist. Two of the clusters correlate with the St. Lawrence fault, a major normal fault created during early Paleozoic rifting events and reactivated by a Devonian meteor impact. This fault is evident in SAR images, as well as in the magnetic and gravimetric fields. The other cluster is located under the St. Lawrence river where the correlation with bathymetric and magnetic data is less evident, due to the thick (up to 8 km) aseismic sedimentary rock cover. The impact crater faults in the exposed portion of the 56 km diameter crater show vividly on SAR images.