Mapping of ground motion amplifications for the Fraser River delta in Greater Vancouver, Canada
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The Fraser River delta in Greater Vancouver, Canada consists of deep soft deposits of silts and clays, and it is well known that the deep soil deposits can amplify the low frequency contents of ground motions. This study aims to investigate the effects of deep soil deposits in the delta on ground motion amplifications by using thorough site response simulations that account for the full soil profiles and a suite of recorded ground motions that covers a wide range of intensity levels. Based on both equivalent-linear and nonlinear site response simulations, the effects of soil depth (represented by natural period of the soil, TS) on ground motion amplifications for various spectral periods are clearly demonstrated. The ground motion amplification maps for various spectral periods and rock ground motion intensity levels are also generated to be used in the regional seismic hazard assessment for infrastructure. It is found that ground motions for long periods are substantially amplified in the center of the delta, while those for short periods are de-amplified when input rock motions are large.
KeywordsFraser River delta ground motion amplification deep soil deposits site response analysis basin depth
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This research was supported by the 2018 Research Fund (1.170059.01) of UNIST (Ulsan National Institute of Science and Technology) and the National Research Foundation of Korea (NRF) with a grant from the Korean government (MSIT) (NRF-2017R1C1B5074430). The author thanks Dr. Hunter for providing the shear-wave velocity profile data, Dr. Emel Seyhan and Dr. Hamed Ashouri for their assistance in processing the shear-wave velocity profile data, and the anonymous reviewers for their detailed and insightful comments that improved the quality of the manuscript.
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