western quebec and southern ontario - Department of Geology

Figure 3.2: Number of stations used versus frequency of the events and their cumulativenumber.Figure 3.3 shows the map distribution of the studied events (N=50) from 1992 to2010. The events are not uniformly distributed, but instead appear to be concentrated inseveral discrete areas. Among the 50 events studied here only 12 events (m>3.5) occurredin southern Ontario, and 38 of them occurred in western Quebec. Most of the earthquakesin western Quebec are concentrated along the Ottawa River and Montreal-Maniwakiregion with a strong NNW-NW trend, transverse to the Appalachians and the St.Lawrence River valley. There is no obvious concentration of earthquake epicentres in thenorthwestern part of the western Quebec (Figure 3.3). A similar relative absence ofearthquakes is also present in the historical data (Chapter 2, Figure 2.3). In southernOntario the earthquakes are concentrated either south of Lake Erie or in western LakeOntario and there is only one event in Georgian Bay (Figure 3.3).28