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Coseismic subsidence in the 1700 great Cascadia earthquake: Coastal estimates versus elastic dislocation models

2004; Geological Society of America; Volume: 116; Issue: 5 Linguagem: Inglês

10.1130/b25369.1

1943-2674

Lucinda J. Leonard, R. D. Hyndman, S. Mazzotti,

Geological and Geochemical Analysis

Research Article| May 01, 2004 Coseismic subsidence in the 1700 great Cascadia earthquake: Coastal estimates versus elastic dislocation models Lucinda J. Leonard; Lucinda J. Leonard 1School of Earth and Ocean Sciences, University of Victoria, Post Office Box 3055 STN CSC, Victoria, British Columbia V8W 3P6, Canada and Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, British Columbia V8L 4B2, Canada Search for other works by this author on: GSW Google Scholar Roy D. Hyndman; Roy D. Hyndman 2Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, British Columbia V8L 4B2, Canada, and School of Earth and Ocean Sciences, University of Victoria, Post Office Box 3055 STN CSC, Victoria, British Columbia V8W 3P6, Canada Search for other works by this author on: GSW Google Scholar Stéphane Mazzotti Stéphane Mazzotti 3Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, British Columbia V8L 4B2, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Lucinda J. Leonard 1School of Earth and Ocean Sciences, University of Victoria, Post Office Box 3055 STN CSC, Victoria, British Columbia V8W 3P6, Canada and Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, British Columbia V8L 4B2, Canada Roy D. Hyndman 2Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, British Columbia V8L 4B2, Canada, and School of Earth and Ocean Sciences, University of Victoria, Post Office Box 3055 STN CSC, Victoria, British Columbia V8W 3P6, Canada Stéphane Mazzotti 3Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, British Columbia V8L 4B2, Canada Publisher: Geological Society of America Received: 28 Mar 2003 Revision Received: 30 Jul 2003 Accepted: 10 Sep 2003 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2004) 116 (5-6): 655–670. https://doi.org/10.1130/B25369.1 Article history Received: 28 Mar 2003 Revision Received: 30 Jul 2003 Accepted: 10 Sep 2003 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Lucinda J. Leonard, Roy D. Hyndman, Stéphane Mazzotti; Coseismic subsidence in the 1700 great Cascadia earthquake: Coastal estimates versus elastic dislocation models. GSA Bulletin 2004;; 116 (5-6): 655–670. doi: https://doi.org/10.1130/B25369.1 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 SocietyGSA Bulletin Search Advanced Search Abstract Seismic hazard assessments for a Cascadia subduction zone earthquake are largely based on the rupture area predictions of dislocation models constrained by geodetic and geothermal data; this paper tests the consistency of the models for the 1700 great Cascadia earthquake with compiled coastal coseismic subsidence as estimated from paleoelevation studies. Coastal estimates have large uncertainties but show a consistent pattern. Greatest coseismic subsidence (∼1–2 m) occurred in northern Oregon/ southern Washington; subsidence elsewhere was ∼0–1 m. Elastic dislocation models constrained by interseismic geodetic and thermal data are used to predict the coseismic subsidence for two likely strain accumulation periods of (i) 800 and (ii) 550 yr of plate convergence and for uniform megathrust slip of 10, 20, 30, and 50 m. The former two models provide a better and equally good fit; predicted subsidence is in broad agreement with marsh estimates. Discrepancies exist, however, at the ends of the subduction zone. In the south, misfit may be due to breakup of the Gorda plate. The discrepancy in the north may be explained if the 1700 event released only part of the accumulated strain there, consistent with long-term net uplift in excess of eustatic sea-level rise. The coseismic slip magnitude, estimated by comparing uniform slip model predictions with marsh coseismic subsidence estimates, is consistent with the M 9 earthquake indicated by Japanese tsunami records. The coseismic slip was greatest in northern Oregon/southern Washington, declining to the north and south. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.