CGRG Bibliography of Canadian Geomorphology
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Author : Bird, A.L.; and Rogers, G.C.
Date : 2002.
Title : Earthquakes of the Queen Charlotte Islands Region, British Columbia.
Publication : Seismological Society of America 2002, Annual Meeting 17-19 April 2002. Victoria Conference Centre, Victoria, British Columbia
Issue :
Page(s) :
Abstract
The Queen Charlotte Fault is a seismically active, transpressional boundary between the Pacific and North American Plates. It's tectonics comprise a region of high seismicity and is the location of Canada's largest instrumentally recorded earthquake; a magnitude 8.1 in 1949. The earthquakes in this area and their associated hazard have come under considerable scrutiny, as southern Queen Charlotte Basin contains a potentially significant source of hydrocarbons. In recent months, there has been interest in the possible lifting of the current moratorium on the exploration for such resources. Despite the occurrence of several large magnitude earthquakes along the Queen Charlotte Fault in the past century, until the mid 1980's little was known of the distribution of smaller earthquakes in the region. A significant improvement in the level of earthquake detection came about with the inception of the Queen Charlotte seismic network in 1982. Analysis of data from this network reveals a more extensive earthquake pattern than that associated directly with the Queen Charlotte Fault. In particular, considerable seismicity occurs east of the fault, in the Queen Charlotte Basin (on Graham Island and in Hecate Strait). With the possible exception of a magnitude 5.3 event in northeastern Hecate Strait in 1990, none of the inland activity appears to be associated with mapped faults. Neither does the distribution of earthquakes, nor the analysis of focal mechanisms, support that events are occurring on any major unmapped faults. To the contrary, the results strongly suggest seismic activity off the main transform fault is occurring on small random faults. For the wide band of earthquakes along the Queen Charlotte Fault, the distribution of events and the diversity of focal mechanisms implies that most earthquakes are not occurring on the main transform fault, but on a system of subsidiary faults. Although fault rupture orientation varies significantly throughout the region, a consistent stress regime of north-northeast compression is revealed, as would be expected in this transpressional environment.
Bibliography of Canadian Geomorphology