Predicting earthquake ground shaking due to 1D soil layering and 3D basin structure in SW British Columbia, Canada

Simple item page
dc.contributor.authorMolnar, Sheri
dc.contributor.supervisorCassidy, John Francis
dc.contributor.supervisorDosso, Stanley Edward
dc.date.accessioned2011-07-20T22:22:51Z
dc.date.available2011-07-20T22:22:51Z
dc.date.copyright2011en_US
dc.date.issued2011-07-20
dc.degree.departmentSchool of Earth and Ocean Sciencesen_US
dc.degree.levelDoctor of Philosophy Ph.D.en_US
dc.description.abstractThis thesis develops and explores two methodologies to assess earthquake ground shaking in southwestern British Columbia based on 1D soil layering and 3D basin structure. To assess site response based on soil layering, microtremor array measurements were conducted at two sites of contrasting geology to estimate Rayleigh-wave dispersion curves. A Bayesian inversion algorithm is developed to invert the dispersion data for the shear-wave velocity (VS) profile together with quantitative uncertainty estimates, accounting rigorously for data error covariance and model parameterization selection. The recovered VS profiles are assessed for reliability by comparison with invasive VS measurements at each site with excellent agreement. Probabilistic site response analysis is conducted based on a sample of VS profiles drawn from the posterior probability density of the microtremor inversion. The quantitative uncertainty analysis shows that the rapid and inexpensive microtremor array method provides sufficient resolution of soil layering for practical characterization of earthquake ground motion. To assess the effects of 3D Georgia basin structure on long-period (> 2 s) ground motion for large scenario earthquakes, numerical 3D finite difference modelling of viscoelastic wave propagation is applied. Both deep (> 40 km) subducting Juan de Fuca plate and crustal (5 km) North America plate earthquakes are simulated in locations congruent with known seismicity. Simulations are calibrated by comparing synthetic waveforms with 36 selected strong- and weak-motion seismograms of the 2001 MW 6.8 Nisqually earthquake. The ratio between predicted peak ground motions in models with and without Georgia basin sediments is applied as a quantitative measure of basin amplification. Steep edges in the upper 1 km of the northwest and southeast extents of the basin are coincident with the appearance of surface waves. Focussing of north-to-northeast propagating surface waves by shallow (< 1 km) basin structure increases ground motion in a localized region of southern Greater Vancouver. This effect occurs for both types of earthquakes located south-southwest of Vancouver at distances greater than ~80 km. The predicted shaking level is increased up to 17 times and the duration of moderate shaking (> 3.4 cm/s) is up to 16 times longer due to the 3D Georgia basin structure.en_US
dc.description.scholarlevelGraduateen_US
dc.identifier.bibliographicCitationMolnar S, SE Dosso & JF Cassidy, 2010. Bayesian inversion of microtremor array dispersion data in southwestern British Columbia, Geophys. J. Int., 183, 923-940.en_US
dc.identifier.bibliographicCitationMolnar S, JF Cassidy, SE Dosso & KB Olsen, 2010. 3D Ground motion in the Georgia basin region of SW British Columbia for Pacific Northwest scenario earthquakes, in Proceedings 9th US National and 10th Canadian Conference on Earthquake Engineering, Toronto, Ontario, July 25-29, Paper 754.en_US
dc.identifier.bibliographicCitationMolnar S, SE Dosso & JF Cassidy, 2011. Site response probability analysis from Bayesian inversion of microtremor array dispersion data, Soil. Dyn. Earth. Eng., in review.en_US
dc.identifier.bibliographicCitationDettmer J, S Molnar, G Steininger, SE Dosso & JF Cassidy, 2011. Trans-dimensional inversion of microtremor array dispersion data with hierarchical autoregressive error models, Geophys. J. Int., in revision.en_US
dc.identifier.bibliographicCitationMolnar S, SE Dosso, & JF Cassidy, 2010. Bayesian inversion of microtremor array dispersion data for subsurface VS structure on the Fraser River delta, in Proceedings 9th US National and 10th Canadian Conference on Earthquake Engineering, Toronto, Ontario, July 25-29, Paper 762.en_US
dc.identifier.urihttp://hdl.handle.net/1828/3417
dc.languageEnglisheng
dc.language.isoenen_US
dc.rights.tempAvailable to the World Wide Weben_US
dc.subjectearthquake ground shakingen_US
dc.subjectsite responseen_US
dc.subjectamplificationen_US
dc.subjectmicrotremor array methoden_US
dc.subjectfinite difference modellingen_US
dc.subjectearthquake simulationen_US
dc.subjectambient vibrationsen_US
dc.subjectBayesian inversionen_US
dc.subjectMonte Carlo simulationen_US
dc.subjectVancouveren_US
dc.subjectVictoriaen_US
dc.subjectearthquakesen_US
dc.subjectmicrotremorsen_US
dc.titlePredicting earthquake ground shaking due to 1D soil layering and 3D basin structure in SW British Columbia, Canadaen_US
dc.typeThesisen_US

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
Molnar_Sheri_PhD_2011.pdf
Size:
22.87 MB
Format:
Adobe Portable Document Format
Download
License bundle
Now showing 1 - 1 of 1
No Thumbnail Available
Name:
license.txt
Size:
1.74 KB
Format:
Item-specific license agreed upon to submission
Description:
Download

Collections

Electronic Theses and Dissertations (ETD)
Theses (Earth and Ocean Sciences)
 
University of Victoria Libraries

We acknowledge and respect the Lək̓ʷəŋən (Songhees and Esquimalt) Peoples on whose territory the university stands, and the Lək̓ʷəŋən and W̱SÁNEĆ Peoples whose historical relationships with the land continue to this day.