Earthquake Ground Motion and 3D Georgia Basin Amplification in Southwest British Columbia: Deep Juan de Fuca Plate Scenario Earthquakes

Abstract

Research Article| January 21, 2014 Earthquake Ground Motion and 3D Georgia Basin Amplification in Southwest British Columbia: Deep Juan de Fuca Plate Scenario Earthquakes Sheri Molnar; Sheri Molnar aUniversity of Victoria, School of Earth and Ocean Sciences, 3800 Finnerty Road , Victoria, British Columbia V8P 5C2smolnar@uvic.casdosso@uvic.ca *Also at Natural Resources Canada, P.O. Box 6000, Sidney, British Columbia V8L 4B2; and now at Department of Civil Engineering, University of British Columbia, 6250 Applied Science Lane, Vancouver, British Columbia V6K 1C1; semolnar@mail.ubc.ca. Search for other works by this author on: GSW Google Scholar John F. Cassidy; John F. Cassidy bNatural Resources Canada, P.O. Box 6000, Sidney, British Columbia V8L 4B2jcassidy@nrcan.gc.cajhe@nrcan.gc.ca †Also at School of Earth and Ocean Sciences, University of Victoria, 3800 Finnerty Road, Victoria, British Columbia, V8P 5C2. Search for other works by this author on: GSW Google Scholar Kim B. Olsen; Kim B. Olsen cSan Diego State University, Department of Geological Sciences, GMCS 231A, 5500 Campanile Dr, San Diego, California 92182‐1020kbolsen@mail.sdsu.edu Search for other works by this author on: GSW Google Scholar Stan E. Dosso; Stan E. Dosso aUniversity of Victoria, School of Earth and Ocean Sciences, 3800 Finnerty Road , Victoria, British Columbia V8P 5C2smolnar@uvic.casdosso@uvic.ca Search for other works by this author on: GSW Google Scholar Jiangheng He Jiangheng He bNatural Resources Canada, P.O. Box 6000, Sidney, British Columbia V8L 4B2jcassidy@nrcan.gc.cajhe@nrcan.gc.ca Search for other works by this author on: GSW Google Scholar Bulletin of the Seismological Society of America (2014) 104 (1): 301–320. https://doi.org/10.1785/0120110277 Article history first online: 14 Jul 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Sheri Molnar, John F. Cassidy, Kim B. Olsen, Stan E. Dosso, Jiangheng He; Earthquake Ground Motion and 3D Georgia Basin Amplification in Southwest British Columbia: Deep Juan de Fuca Plate Scenario Earthquakes. Bulletin of the Seismological Society of America 2014;; 104 (1): 301–320. doi: https://doi.org/10.1785/0120110277 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyBulletin of the Seismological Society of America Search Advanced Search Abstract Finite‐difference modeling of 3D long‐period (>2 s) ground motions for large (Mw 6.8) scenario earthquakes is conducted to investigate effects of the Georgia basin structure on ground shaking in Greater Vancouver, British Columbia, Canada. Scenario earthquakes include deep (>40 km) subducting Juan de Fuca (JdF) plate earthquakes, simulated in locations congruent with known seismicity. Two sets of simulations are performed for a given scenario earthquake using models with and without Georgia basin sediments. The chosen peak motion metric is the geometric mean of the two orthogonal horizontal components of motion. The ratio between predicted peak ground velocity (PGV) for the two simulations is applied here as a quantitative measure of amplification due to 3D basin structure. A total of 10 deep subducting JdF plate earthquakes are simulated within 100 km of Greater Vancouver. Simulations are calibrated using records from the 2001 Mw 6.8 Nisqually earthquake. On average, the predicted level of average PGV at stiff soil sites across Greater Vancouver for an Mw 6.8 JdF plate earthquake is 3.2 cm/s (modified Mercalli intensity IV–V). The average increase in PGV due to basin structure across Greater Vancouver is 3.1. Focusing of north‐northeast‐propagating surface waves by shallow (<1 km) basin structure increases ground motion in a localized region of south Greater Vancouver; hence, scenario JdF plate earthquakes located ≥80 km south‐southwest of Vancouver are potentially the most hazardous.Online Material: Depth slices of 3D velocity model, peak ground velocity maps, and snapshots and videos of wave propagation. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.