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Title A Bernstein polynomial model in Bayesian inversion of surface-wave dispersion for earthquake site response in British Columbia, Canada
AuthorGosselin, J M; Cassidy, J F; Dosso, S E
Alt SeriesEarth Sciences Sector, Contribution Series 20160031
PublisherInternational Association of Earthquake Engineers
Meeting16th World Conference on Earthquake Engineering; Santiago; CL; January 9-13, 2017
Documentserial
Lang.English
Mediapaper
ProvinceBritish Columbia
NTS103H; 103I
AreaKitimat
Lat/Long WENS-131.5000 -126.0000 55.0000 52.0000
Subjectstectonics; s waves; wave propagation; velocity surveys; seismic velocities; earthquakes; earthquake studies; modelling; Bayesian inversion; Bernstein polynomial basis; earthquake response
Illustrationslocation maps; graphs; histograms
ProgramWestern Canada Geohazards Project, Public Safety Geoscience
AbstractKnowledge of near-surface properties of the soil column, in particular, the shear-wave velocity (Vs) profile over the upper 10s of meters, is important for characterizing the expected ground response to earthquake shaking at a specific site. Non-invasive and passive methods based on recording ambient seismic noise are increasingly popular for estimating Vs structure with minimal cost and site disruption. This paper applies a fully nonlinear Bayesian inversion methodology, based on parallel tempering, to estimate Vs profiles and uncertainties using surface-wave dispersion data processed from passive seismic array recordings. In the inversion, the Vs profile is parameterized using a Bernstein polynomial basis, which efficiently characterizes general depth-dependent Vs gradients in the soil column. Bernstein polynomials provide a stable parameterization in that small perturbations to the model parameters (basis function coefficients) result in only small perturbations to the Vs profile. Shear-wave velocity profiles and uncertainties are obtained from the velocity-depth marginal posterior probability density. This methodology is applied to passive seismic array recordings collected at several sites in Kitimat, British Columbia, Canada, a region where earthquake site response is of significant interest. The probabilistic Vs profile results ultimately provide probabilistic estimates of site response factors such as peak ground velocity/acceleration and Vs30.
Summary(Plain Language Summary, not published)
Knowledge of near-surface properties of the soil column, in particular, the shear-wave velocity (Vs) profile over the upper 10's of metres, are important for characterizing the expected ground response to earthquake shaking. In this study we improve upon non-invasive and passive techniques that use recordings of ambient seismic noise (and so are low-cost, fast and minimise site disruption). We apply an advanced inversion methodology to estimate Vs structure and uncertainties from surface-wave recordings made on a seismic array. This new methodology is applied to passive seismic array recordings collected at five sites in Kitimat, British Columbia, Canada and we compare our inversion results from several sites to active-source reflection data collected nearby.
GEOSCAN ID298723