Thesis Format
Integrated Article
Degree
Doctor of Philosophy
Program
Geophysics
Collaborative Specialization
Hazards, Risks, and Resilience
Supervisor
Molnar, Sheri
2nd Supervisor
Wang, Jinfei
Co-Supervisor
Abstract
Metro Vancouver faces a significant earthquake hazard due to its proximity to the Cascadia subduction zone. As Metro Vancouver has a high population density, the region's heterogeneous geology which includes uneven, glacially eroded bedrock overlain by thick Quaternary deposits contributes significantly to the heightened seismic risk. Geodata plays an essential role in seismic microzonation mapping. A comprehensive geodatabase specific to western Metro Vancouver is developed from open-source and proprietary sources in combination with field geodata collection to achieve regional seismic microzonation mapping. This geodatabase enabled development of an empirical relationship between standard penetration resistance and shear-wave velocity of Holocene post-glacial sediments, and 3D seismic geology and shear-wave velocity models of Metro Vancouver. The potential impact of a comprehensive regional database of seismic site conditions within Metro Vancouver to seismic hazard assessment is examined in terms of reducing seismic design ground motions of the 2020 National Building Code of Canada based on in situ shear-wave velocity measurements of the top 30 meters. We explore the variability in key seismic site characterization measures most often used for seismic microzonation mapping to evaluate the impact on mapping and communication of seismic microzonation of Metro Vancouver. We find that the seismic microzonation of Metro Vancouver depends on the chosen seismic site parameter and that classification schemes with greater class divisions are beneficial to communicating the great variability in seismic site conditions in Metro Vancouver.
Summary for Lay Audience
Metro Vancouver faces a significant earthquake hazard due to its proximity to the Cascadia subduction zone. The area's diverse ground or site conditions are characterized by uneven, glacially eroded bedrock covered by younger thick sediment deposits that contribute greatly to the heightened seismic hazard. To evaluate this hazard accurately, it is crucial to understand the variability in ground conditions across Metro Vancouver. The act of defining areas or zones of ground conditions that will behave similarly during earthquake shaking is known as seismic microzonation mapping. This type of earthquake hazard mapping is essential to identify regions that are more susceptible to earthquake ground shaking, liquefaction, or landslides. Seismic microzonation maps aid in designing resistant structures, planning safer communities, and preparing our emergency response to future earthquake shaking. To impact seismic microzonation mapping of Metro Vancouver, a comprehensive database of geological, geophysical, and geotechnical measurements at over 15,000 locations across Metro Vancouver is compiled from a variety of data sources. The great effort in generating this geodatabase is worthwhile because it enables improvement in the prediction of subsurface material properties as well as development of regional-scale models of these subsurface material properties that are important to seismic hazard prediction for the Metro Vancouver region. The impact of this study’s improvement in understanding seismic site conditions across Metro Vancouver are demonstrated in terms of the potential reduction to seismic design ground motions of the 2020 Canadian building code as well as trial seismic microzonation mapping.
Recommended Citation
Adhikari, Sujan Raj, "Development of a Regional Geodatabase and 3D Models of Metro Vancouver and Their Use and Impact to Regional Seismic Hazard Mapping" (2024). Electronic Thesis and Dissertation Repository. 9949.
https://ir.lib.uwo.ca/etd/9949
Creative Commons License
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