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TitleMapping crustal structure of the Nechako-Chilcotin plateau using teleseismic receiver function analysis
AuthorKim, H S; Cassidy, J F; Dosso, S E; Kao, H
SourceCanadian Journal of Earth Sciences vol. 51, 2014 p. 407-417,
Alt SeriesEarth Sciences Sector, Contribution Series 20130381
PublisherNational Research Council of Canada
Mediapaper; on-line; digital
File formatpdf
ProvinceBritish Columbia
NTS92N; 92O; 93B; 93C; 93F; 93G
AreaNechako-Chilcotin plateau
Lat/Long WENS-126.0000 -122.0000 54.0000 51.0000
Subjectsgeophysics; mapping techniques; computer mapping; crustal studies; geophysical surveys; s waves; seismic waves; teleseismic surveys
Illustrationslocation maps; models; tables
ProgramTargeted Hazard Assessments in Western Canada, Public Safety Geoscience
AbstractThis paper presents results of a passive-source seismic mapping study in the Nechako-Chilcotin plateau of central British Columbia, with the ultimate goal of contributing to assessments of hydrocarbon and mineral potential of the region. For the present study, an array of nine seismic stations was deployed in 2006-2007 to sample a wide area of the Nechako-Chilcotin plateau. The specific goal was to map the thickness of the sediments and volcanic cover, and the overall crustal thickness and structural geometry beneath the study area. This study utilizes recordings of about 40 distant earthquakes from 2006 to 2008 to calculate receiver functions, and constructs S-wave velocity models for each station using the Neighbourhood Algorithm inversion. The surface sediments are found to range in thickness from about 0.8 to 2.7 km, and the underlying volcanic layer from 1.8 to 4.7 km. Both sediments and volcanic cover are thickest in the central portion of the study area. The crustal thickness ranges from 22 to 36 km, with an average crustal thickness of about 30-34 km. A consistent feature observed in this study is a low-velocity zone at the base of the crust. This study complements other recent studies in this area, including active-source seismic studies and magnetotelluric measurements, by providing site-specific images of the crustal structure down to the Moho and detailed constraints on the S-wave velocity structure.
Summary(Plain Language Summary, not published)
The Nechako Basin area of south central British Columbia has long been an area of interest for oil and gas potential. However, much of the sedimentary basin is covered with a layer of volcanic basalts, making traditional seismic exploration methodologies (seismic reflection) ineffective. We have used an innovative technique of using recordings of distant earthquakes (waves coming 'from below') to image the sediments and the overall basin geometry. Our study provides images of the basin that can be used to evaluate the oil and gas potential of the region, and also has applications for volcanic and earthquake hazard (this basin lies within the Anahim volcanic belt that experienced a swarm of thousandas of earthquakes in 2008).