HR: 1330h
AN: S42A-0143    [PDF]
TI: Northern Cascadia Earthquake Catalogue, 1980-Present
AU: * Mulder, T L
EM: mulder@pgc.nrcan.gc.ca
AF: Geological Survey of Canada, Pacific Geoscience Centre, PO Box 6000, Sidney, BC V8L 4B2 Canada
AU: Rogers, G C
EM: rogers@pgc.nrcan.gc.ca
AF: Geological Survey of Canada, Pacific Geoscience Centre, PO Box 6000, Sidney, BC V8L 4B2 Canada
AB: The Cascadia subduction zone trancends the international boundary between Canada and the United States. This is where the Juan de Fuca plate subducts beneath the North America plate from Vancouver Island, British Columbia in the north and extending south through Washington, and Oregon. Seismicity catalogues exist for each side of the border: the Western Canadian Earthquake Catalogue (Geological Survey of Canada at the Pacific Geoscience Centre (PGC), Sidney, BC) and the Pacific Northwest Earthquake Catalogue (University of Washington (UW), Seattle, Washington). It is desirable for many kinds of studies and displays to have one catalogue. To this end we have merged the two catalogues together into one, which is consistent in location and magnitude. Earthquakes have been tagged as to whether they occurred in the North America plate or the Juan de Fuca plate. The northern Cascadia Earthquake Catalogue has proven extremely useful for research, plotting, and display of the seismicity patterns in this region. Cross-sections of seismicity perpendicular to the subduction front and running through Port Alberni, BC, Victoria, BC, and Seattle, Washington clearly show variations in the angle of dip of the subducting plate. Magnitude comparison between the two networks required a magnitude correction for the smallest events. For UW magnitudes less than 2.6, M$_{L}$(PGC) = M$_{C}$(UW) - 0.1; for UW magnitudes greater than or equal to 2.6, M$_{L}$(PGC) = M$_{C}$(UW).
DE: 7230 Seismicity and seismotectonics
SC: Seismology [S]
MN: 2003 Fall Meeting