Rupture area and displacement of past Cascadia great earthquakes from coastal coseismic subsidence

Abstract

Research Article| November 01, 2010 Rupture area and displacement of past Cascadia great earthquakes from coastal coseismic subsidence Lucinda J. Leonard; Lucinda J. Leonard † 1Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, British Columbia V8L 4B2, Canada †E-mail: lleonard@nrcan.gc.ca Search for other works by this author on: GSW Google Scholar Claire A. Currie; Claire A. Currie 2Department of Physics, University of Alberta, Edmonton, Alberta T6G 2G7, Canada Search for other works by this author on: GSW Google Scholar Stéphane Mazzotti; Stéphane Mazzotti 1Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, British Columbia V8L 4B2, Canada3School of Earth and Ocean Sciences, University of Victoria, PO Box 3065 STN CSC, Victoria, British Columbia V8W 3V6, Canada Search for other works by this author on: GSW Google Scholar Roy D. Hyndman Roy D. Hyndman 1Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, British Columbia V8L 4B2, Canada3School of Earth and Ocean Sciences, University of Victoria, PO Box 3065 STN CSC, Victoria, British Columbia V8W 3V6, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Lucinda J. Leonard † 1Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, British Columbia V8L 4B2, Canada Claire A. Currie 2Department of Physics, University of Alberta, Edmonton, Alberta T6G 2G7, Canada Stéphane Mazzotti 1Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, British Columbia V8L 4B2, Canada3School of Earth and Ocean Sciences, University of Victoria, PO Box 3065 STN CSC, Victoria, British Columbia V8W 3V6, Canada Roy D. Hyndman 1Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, British Columbia V8L 4B2, Canada3School of Earth and Ocean Sciences, University of Victoria, PO Box 3065 STN CSC, Victoria, British Columbia V8W 3V6, Canada †E-mail: lleonard@nrcan.gc.ca Publisher: Geological Society of America Received: 18 Jun 2009 Revision Received: 19 Sep 2009 Accepted: 14 Oct 2009 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2010 Geological Society of America GSA Bulletin (2010) 122 (11-12): 2079–2096. https://doi.org/10.1130/B30108.1 Article history Received: 18 Jun 2009 Revision Received: 19 Sep 2009 Accepted: 14 Oct 2009 First Online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Lucinda J. Leonard, Claire A. Currie, Stéphane Mazzotti, Roy D. Hyndman; Rupture area and displacement of past Cascadia great earthquakes from coastal coseismic subsidence. GSA Bulletin 2010;; 122 (11-12): 2079–2096. doi: https://doi.org/10.1130/B30108.1 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 Coastal marshes record a 6500 yr history of coseismic displacements in great earthquakes at the Cascadia subduction zone. We compiled estimates of coseismic displacement for past megathrust events based on correlations with megathrust-triggered turbidites, and estimated megathrust slip based on comparisons of marsh displacements with dislocation model predictions. Age-correlated marsh data are compatible with event rupture extents defined by the published turbidite record, and a 6500 yr mean recurrence interval that increases northward from ∼230 to ∼480 yr. Within the constraints of the marsh data, the width of the coseismic rupture zone generally agrees with the downdip width of the interseismic locked zone inferred from geodetic and thermal data. In southernmost Cascadia, where the model does not include the complex deformation near the Mendocino triple junction, the coastal data may be better fit by a model with an ∼25% narrower rupture than that inferred from regional geophysical data. At each coastal marsh site, coseismic displacements are roughly similar from event to event, independent of the time since the previous event. Slip in the A.D. 1700 earthquake was consistent with the preceding interval of strain accumulation (∼200 yr) only at the northern and southern ends of the margin, but it was apparently much higher in southern Washington and northern Oregon, possibly indicating postseismic contamination and/or catch-up coseismic slip to make up for a deficit in the preceding event. Overall agreement between the dislocation models and the marsh data for most of the margin implies that such models can be usefully applied to rupture and ground shaking predictions. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.