Seismic hazard site assessment in Kitimat, British Columbia, via bernstein-polynomial-based inversion of surface-wave dispersion​

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dc.contributor.authorGosselin, Jeremy M.
dc.contributor.supervisorDosso, Stan
dc.contributor.supervisorCassidy, John
dc.date.accessioned2016-12-20T21:41:10Z
dc.date.available2016-12-20T21:41:10Z
dc.date.copyright2016en_US
dc.date.issued2016-12-20
dc.degree.departmentSchool of Earth and Ocean Sciencesen_US
dc.degree.levelMaster of Science M.Sc.en_US
dc.description.abstractThis thesis applies a fully nonlinear Bayesian inversion methodology to estimate shear-wave velocity (Vs) profiles and uncertainties from surface-wave dispersion data extracted from ambient seismic noise. In the inversion, the Vs profile is parameterized using a Bernstein polynomial basis, which efficiently characterizes general depth-dependent gradients in the soil/sediment 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. The inversion solution is defined in terms of the marginal posterior probability for Vs as a function of depth, estimated using Metropolis-Hastings sampling with parallel tempering. This methodology is validated via inversion of synthetic dispersion data as well as previously-considered data inverted using different parameterizations. The approach considered here is better suited than layered modelling approaches in applications where smooth gradients in geophysical parameters are expected, and/or the observed data are diffuse and not sensitive to fine-scale discrete layering (such as surface-wave dispersion). The Bernstein polynomial representation is much more general than other gradient-based models such that the form of the gradients are determined by the data, rather than by subjective parameterization choice. The Bernstein inversion methodology is also applied to dispersion data processed from passive array recordings collected in the coastal community of Kitimat, British Columbia. The region is the proposed site of several large-scale industrial development projects and has great economic and environmental significance for Canada. The inversion results are consistent with findings from other geophysical studies in the region and are used in a site-specific seismic hazard analysis. The level of ground-motion amplification expected to occur during an earthquake due to near-surface Vs structure is probabilistically quantified, and predicted to be significant compared to reference (hard ground) sites.en_US
dc.description.scholarlevelGraduateen_US
dc.identifier.urihttp://hdl.handle.net/1828/7676
dc.languageEnglisheng
dc.language.isoenen_US
dc.rightsAvailable to the World Wide Weben_US
dc.subjectSeismic Hazarden_US
dc.subjectInverse Problemsen_US
dc.subjectPassive Seismicen_US
dc.subjectSurface Wavesen_US
dc.titleSeismic hazard site assessment in Kitimat, British Columbia, via bernstein-polynomial-based inversion of surface-wave dispersion​en_US
dc.typeThesisen_US

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