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TitleSeismic attenuation in northeast British Columbia using the coda Q method
AuthorFarahbod, A M; Cassidy, J FORCID logo; Kao, HORCID logo
SourceCanadian Society of Exploration Geophysicists, Recorder vol. 44, issue 7, 2019 p. 1-14 Open Access logo Open Access
LinksOnline - En ligne
Alt SeriesNatural Resources Canada, Contribution Series 20190300
PublisherCanadian Society of Exploration Geophysicists
Mediapaper; on-line; digital
File formatpdf; html
ProvinceBritish Columbia
NTS93N; 93O; 93P; 94A; 94B; 94C; 94F; 94G; 94H; 94I; 94J; 94K; 94N; 94O; 94P
AreaFort Nelson; Fort St. John; Dawson Creek
Lat/Long WENS-125.0000 -120.0000 60.0000 55.0000
Subjectsgeophysics; tectonics; fossil fuels; Nature and Environment; Science and Technology; Economics and Industry; seismology; seismological network; earthquakes; earthquake magnitudes; seismic waves; s waves; attenuation; crustal studies; lithosphere; models; petroleum industry; hydrocarbon recovery; hydraulic fracturing; tectonic setting; tectonic history; miogeosynclines; Canadian Cordillera; North American Craton; Canadian National Seismic Network; Stikinia Terrane; Quesnellia Terrane; Foreland Belt; Cassiar Platform; Cassiar Terrane; Rocky Mountain Platform; Kechika Trench; Rocky Mountain; Windermere High; Omineca Belt; Intermontane Belt; Horn River Basin; Montney Formation; Data processing
Illustrationslocation maps; geoscientific sketch maps; seismograms; tables; photographs
ProgramPublic Safety Geoscience Assessing Earthquake Geohazards
Released2019 12 01
AbstractCoda-wave attenuation is an important criterion for the study of elastic properties of the lithosphere. In this article, attenuation is measured in northeast British Columbia using records from 9 new stations of the Canadian National Seismic Network (CNSN). Our dataset is comprised of 402 earthquakes recorded between August 2013 and January 2017, with magnitudes ranging from 1.5 to 4.7, depths from 1 to 14 km and epicentral distances of 15 to 100 km. The coda-wave attenuation is measured by means of QC based on the single-backscattering model. Coda windows were selected to start at tC = 2tS (two times the travel time of the direct S wave), and were filtered at center frequencies of 2, 4, 8, 12 and 16 Hz. Our study reveals a consistent pattern in the northeast of British Columbia that shows very low Q0 values. Based on our calculations, Q0 varies between 43 and 71 over the range of a2 from 20 to 70 at the new CNSN stations (NBC4, 5, 7, 8 and NAB1) at the western edge of the continental craton. This is consistent with a previous study (Farahbod & Cassidy, 2018) that shows a low average Q0 at the FNBB and BMBC stations (46-76 over the range of a2 from 20 to 70). Those stations were deployed in a region of active hydraulic fracturing operations, suggesting that injections could be a contributing factor for low Q0 values.
Summary(Plain Language Summary, not published)
In this study we analyse small earthquakes in northeast British Columbia to examine seismic wave attenuation (one of the key factors for seismic hazard assessment). We find high seismic attenuation rates in this region - higher than expected for this region on the eastern edge of the cordillera. Possible explanations include association with fluid injections in the area or the thicker sedimentary sequence.

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