western quebec and southern ontario - Department of Geology
western quebec and southern ontario - Department of Geology
western quebec and southern ontario - Department of Geology
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
CHAPTER 1INTRODUCTION1.1 IntroductionEastern Canada is part <strong>of</strong> the stable interior <strong>of</strong> the North American plate. Our knowledge<strong>of</strong> the cause <strong>of</strong> seismic activity in Eastern Canada is far from complete. Regionalseismicity plays an important role in the study <strong>of</strong> tectonic processes <strong>and</strong> can contribute tothe underst<strong>and</strong>ing <strong>of</strong> the nature <strong>of</strong> these processes <strong>and</strong> to the evaluation <strong>of</strong> the seismichazard. Accurate locations for earthquake hypocentres are important in identifyingpotential seismogenic features <strong>and</strong> developing a relationship between seismicity <strong>and</strong> thetectonic structures <strong>and</strong> features. Other source parameters such as focal mechanisms canalso provide information on the tectonic structures on which the earthquakes occur. Theearthquake source parameters also provide information about the regional <strong>and</strong> local stressdistributions within the plates, as well as the geometry <strong>and</strong> kinematics <strong>of</strong> fault slips.Accurate estimation <strong>of</strong> the magnitude <strong>of</strong> the seismic events can also provide insight intothe size <strong>of</strong> the active faults. Earthquakes with magnitude <strong>of</strong> m N ≤ 3 have rupture sizes inthe order <strong>of</strong> 1-100 metres with slips <strong>of</strong> less than a few centimetres, while earthquakeswith larger magnitudes (m N > 5) may have rupture dimensions at the scale <strong>of</strong> kilometres(e.g. Johnston, 1993).1