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TitleCrustal structure of eastern and central Canada from a Neighborhood Algorithm inversion
AuthorBent, A L; Kao, H
SourceGeological Survey of Canada, Open File 7833, 2015, 68 pages,
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
File formatpdf
ProvinceManitoba; Ontario; Quebec
NTS1; 2; 3; 10; 11; 12; 13; 14; 20; 21; 22; 23; 24; 30; 31; 32; 33; 34; 42; 43; 44; 52; 53; 54
Lat/Long WENS-96.0000 -52.0000 60.0000 44.0000
Subjectsgeophysics; mathematical and computational geology; earthquakes; earthquake studies; earthquake foci; seismographs; seismicity; seismic velocities; remote sensing; geological hazards
Illustrationslocation maps; graphs; plots; profiles
ProgramWestern Canada Geohazards Project, Public Safety Geoscience
Released2015 07 21
AbstractTeleseismic receiver functions created from waveforms of large earthquakes recorded by twenty-one broadband stations of the Canadian National Seismograph Network in eastern and central Canada were analyzed to determine the shear wave velocity structure of the crust and uppermost mantle beneath these stations. Preliminary models were obtained from a simple, linear inversion and then an improved Neighborhood Algorithm was employed to enable a larger number of models to be tested and to provide robust uncertainty estimates of the models. Common features are observed at stations falling within the same geological provinces. While azimuthal variations in receiver functions may be an indication of dipping structure, most stations in this study showing an azimuthal dependence are located near the boundaries of two or more geological provinces. The receiver functions at some azimuths and the structure obtained by modeling them may more closely resemble that of a neighboring province through which the waves propagated for a significant portion of their path. The goal of structural modeling is to provide improved models for use in earthquake location and focal mechanism determination, which in turn should improve our understanding of regional seismotectonics and seismic hazard. A test case using the aftershock sequence of a moderate earthquake shows some clear advantages of using a local velocity model over a generic one.
Summary(Plain Language Summary, not published)
The crustal structure beneath twenty-one seismograph stations in eastern and central Canada is determined by modeling receiver functions derived from earthquakes recorded at teleseismic distances. A Neighborhood Algorithm method is used to test a large number of models and rank their relative fits to the data. Improved velocity models lead to improved earthquake locations and eventually to improved hazard estimates. An example showing the advantages of using a regional model over a continental-scale model is shown using a suite of aftershocks.