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TitleAssessment of ground-motion models for use in the British Columbia North Coast region, Canada
AuthorAllen, T I; Brillon, C
SourceBulletin of the Seismological Society of America vol. 105, no. 2B, 2015 p. 1193-1205,
Alt SeriesEarth Sciences Sector, Contribution Series 20150109
PublisherSeismological Society of America (SSA)
Mediapaper; on-line; digital
File formatpdf
ProvinceBritish Columbia
NTS102O/10; 102O/11; 102O/12; 102O/13; 102O/14; 102O/15; 103B/02; 103B/03; 103B/04; 103B/05; 103B/06; 103B/07; 103B/10; 103B/11; 103B/12; 103B/13; 103B/14; 103B/15; 103C; 103F; 103G/02; 103G/03; 103G/04; 103G/05; 103G/06; 103G/07; 103G/10; 103G/11; 103G/12; 103G/13; 103G/14; 103G/15; 103J/02; 103J/03; 103J/04; 103J/05; 103J/06; 103J/07; 103K/01; 103K/02; 103K/03; 103K/04; 103K/05; 103K/06; 103K/07; 103K/08
AreaBCNC; Haida Gwaii
Lat/Long WENS-134.0000 -130.5000 54.5000 51.5000
Subjectsgeophysics; earthquakes; earthquake risk; earthquake studies; earthquake magnitudes; seismic risk; seismic surveys
Illustrationstables; bar graphs; charts; location maps; seismic maps; graphs
ProgramMarine Geohazards Mapping & Monitoring (MGMM)
Released2015 04 14
AbstractThe MW 7.8 28 October 2012 Haida Gwaii earthquake was the second largest earthquake recorded in Canada's territory in historic times and was strongly felt across the North Coast British Columbia (NCBC) region. Data from the Haida Gwaii sequence and other events in the region are compiled for 57 earthquakes between MW 4.6 and 7.8 that occurred between 1996 and 2014. Pseudo spectral accelerations at 5% damping are calculated and are compared against several modern ground-motion models (GMMs) using different binning criteria (e.g. distance, magnitude, mechanism, source-to-site azimuth, and time of occurrence). Overall, no one model is found to be appropriate for the NCBC region, with GMMs generally overestimating recorded near source (i.e. less than 100 km) ground motions by factors of two or more across most of the spectral period range.
Earthquake motions recorded prior to and including the 2012 MW 7.8 earthquake were generally more comparable with GMMs at longer spectral periods, but still possessed significant biases based on residual analyses. Additionally, earthquakes with normal mechanisms were found to be deficient in short-to-mid period motions relative to strike- and reverse-slip events.
Summary(Plain Language Summary, not published)
The North Coast region of British Columbia is emerging as a region of high strategic importance to Canada's economy. With its location near the Pacific/North America plate boundary, this region is vulnerable to the negative impacts of earthquakes. Natural Resources Canada is mandated to develop National Seismic Hazard Models, which underpin the National Building Code of Canada. The production of these models requires assumptions on the use of Ground Motion Models (GMMs), often with little empirical evidence to guide their selection. Using recorded ground-motion data from 1996 to 2014, including from the MW 7.8 2012 Haida Gwaii earthquake sequence, we evaluate several modern GMMs commonly used in seismic hazard analyses. The GMMs generally overestimate recorded near source (i.e. less than 100 km) ground motions by factors of two or more across most of the spectral period range. These results suggest that the GMMs used in the BC North Coast region may not be appropriate and should be re-evaluated in light of these new data.

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