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TitleRegional centroid-moment-tensor analysis for earthquakes in Canada and adjacent regions: an update
AuthorKao, H; Shan, S -J; Bent, A; Woodgold, C; Rogers, G; Cassidy, J F; Ristau, J
SourceSeismological Research Letters vol. 83, no. 3, 2012 p. 505-515, https://doi.org/10.1785/gssrl.83.3.505
Year2012
Alt SeriesEarth Sciences Sector, Contribution Series 20110279
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
ProvinceBritish Columbia; Alberta; Saskatchewan; Manitoba; Ontario; Quebec; New Brunswick; Nova Scotia; Prince Edward Island; Newfoundland and Labrador; Northwest Territories; Yukon; Nunavut
NTS1; 2; 3; 10; 11; 12; 13; 14; 15; 16; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 52; 53; 54; 55; 56; 57; 58; 59; 62; 63; 64; 65; 66; 67; 68; 69; 72; 73; 74; 75; 76; 77; 78; 79; 82; 83; 84; 85; 86; 87; 88; 89; 92; 93; 94; 95; 96; 97; 98; 99; 102; 103; 104; 105; 106; 107; 114O; 114P; 115; 116; 117; 120; 340; 560
Lat/Long WENS-141.0000 -50.0000 90.0000 41.7500
Subjectsgeophysics; earthquakes; earthquake studies; earthquake foci; seismographs; seismicity; seismic velocities
Illustrationslocation maps; graphs; plots; tables
ProgramNational-Scale Geohazard Assessments, Public Safety Geoscience
Abstract(unpublished)
Regional centroid-moment-tensor (CMT) inversion for earthquakes in western Canada was first established nearly a decade ago. Since then, the practice of regional CMT analysis and the Canadian National Seismograph Network (CNSN), the primary source of seismic waveform data, have undergone constant improvements. One specific new feature is the utilization of a two-tier weighting scheme in the inversion to adequately differentiate the influence of data quality and station distribution. The inversion also allows different velocity models for different source-station paths that pass through complex tectonic regimes. A total of 706 regional CMT solutions have been obtained for earthquakes in and around Canada dated between 1995 and 2011 (up to mid-June). About 40% of them have moment magnitude (Mw) in the 4.0¿4.5 range, with another third in 4.5¿5.0. Geographically, the Revere-Dellwood-Wilson Fault Zone offshore west of northern Vancouver Island has the highest number of events. For western Canada, a significant discrepancy between Mw and local magnitude (ML) exists for regions where local tectonic settings are complicated by the existence of oceanic/subducting plates, but the difference becomes negligible for crustal events within the continental interior. For eastern Canada, the magnitude difference (Mw-MN) is estimated to be -0.6. The overall relationship between earthquake occurrence rate and size follows the well-known b-value=1 line between Mw=4.5 and 6.0, suggesting that the completeness of CNSN regional CMT database deteriorates for Mw<4.5.
GEOSCAN ID289589