western quebec and southern ontario - Department of Geology
western quebec and southern ontario - Department of Geology
western quebec and southern ontario - Department of Geology
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CHAPTER 5ANALYSIS AND DISCUSSION5.1 IntroductionPrevious studies have attempted to discern trends in seismicity <strong>and</strong> relate them to regionalgeology or tectonics, which led to increased efforts to map basement fault zones <strong>and</strong> tore-evaluate seismic hazard in many areas <strong>of</strong> Eastern North America which were formerlyregarded as low risk areas (Barosh, 1986; Jacobi <strong>and</strong> Fountain, 1993; Seeber <strong>and</strong>Armbruster, 1993; Talwani, 1999). Sbar <strong>and</strong> Sykes (1973) proposed that earthquakes inEastern North America occur in areas <strong>of</strong> high stress along existing fault zones <strong>of</strong> latePaleozoic or younger age. Yang <strong>and</strong> Aggarwal (1981) distinguished two seismogenicprovinces, that is, the Adirondack–<strong>western</strong> Quebec province <strong>and</strong> the Appalachianprovince, using the locations <strong>of</strong> 364 earthquakes <strong>of</strong> magnitude 2 to 5, <strong>and</strong> 22 focalmechanism solutions. Adams <strong>and</strong> Basham (1989) defined four seismic zones insoutheastern Canada <strong>and</strong> argued that most <strong>of</strong> the events were associated with thereactivation <strong>of</strong> late Proterozoic to Paleozoic rift system along the St. Lawrence <strong>and</strong>Ottawa Rivers. In this chapter seismic source parameters (focal depth strike orientation,plunging angle P-axes <strong>and</strong> T-axes) determined in the present study are combined with the59
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