Why are there so many earthquakes in western Canada?

1 ANSWERS

1. Guest6590
   

   Western Canada is the most seismically active region in Canada. It consists of several discrete areas of intense earthquake activity, each corresponding to a particular plate tectonic regime. The most seismic of these regions is offshore, west of Vancouver Island. More than 100 earthquakes with a magnitude of 5 or greater have occurred here in the past 70 years. Most of the seismicity occurs in areas of fractured oceanic crust, which mark boundaries of small plates known as the Explorer and Juan de Fuca plates.
   Earthquake activity is also high in the Cascadia Subduction Zone. Here, the Juan de Fuca Plate dips below the easterly neighbouring North American plate. Thus, both deep (dipping plate) and shallow (overriding plate) earthquakes occur in this zone, though no earthquakes occur at the interface of the plates. Another region of high seismicity is defined by a zone of plate breakage or "faulting" immediately west of the Queen Charlotte Islands ("the Queen Charlotte fault"). Earthquakes of magnitude 7 occurred here in May of 1929 and June of 1970.
   The St. Elias Mountains, southwest Yukon Territory and the extreme northwest of B.C., too, is a highly seismic region. This is because of plate margin deformation between two converging plates in the area (the "Pacific" to the west and "North American" to the east.)
   Finally, the Canadian Cordillera typically shows intense seismicity north of 60 degrees in a broad zone through the Mackenzie and Richardson Mountains. The largest earthquake recorded here, with magnitude of 6.9, occured in the Mackenzie Mountains in December, 1985. South of 60 N, seismicity drops off markedly away from the coast to a low level through much of the Cordillera, though it is slightly higher in the Coast Mountains from southern British Columbia to the Yukon Border.

   Report (0) (0)  |   12 years, 8 month(s) ago