On the Depth Extent of Coseismic Rupture

Research Article| February 13, 2018 On the Depth Extent of Coseismic Rupture N. M. Beeler; N. M. Beeler aU.S. Geological Survey, Cascades Observatory, 1300 Cardinal Court, Building 10, Suite 100, Vancouver, Washington 98683, nbeeler@usgs.gov Search for other works by this author on: GSW Google Scholar G. Hirth; G. Hirth bDepartment of Earth, Environmental and Planetary Sciences, Brown University, 324 Brook Street, Providence, Rhode Island 02912 Search for other works by this author on: GSW Google Scholar T. E. Tullis; T. E. Tullis bDepartment of Earth, Environmental and Planetary Sciences, Brown University, 324 Brook Street, Providence, Rhode Island 02912 Search for other works by this author on: GSW Google Scholar C. H. Webb C. H. Webb bDepartment of Earth, Environmental and Planetary Sciences, Brown University, 324 Brook Street, Providence, Rhode Island 02912cNow at Department of Earth and Planetary Sciences, University of California Davis, One Shields Avenue, Davis, California 95616. Search for other works by this author on: GSW Google Scholar Author and Article Information N. M. Beeler aU.S. Geological Survey, Cascades Observatory, 1300 Cardinal Court, Building 10, Suite 100, Vancouver, Washington 98683, nbeeler@usgs.gov G. Hirth bDepartment of Earth, Environmental and Planetary Sciences, Brown University, 324 Brook Street, Providence, Rhode Island 02912 T. E. Tullis bDepartment of Earth, Environmental and Planetary Sciences, Brown University, 324 Brook Street, Providence, Rhode Island 02912 C. H. Webb bDepartment of Earth, Environmental and Planetary Sciences, Brown University, 324 Brook Street, Providence, Rhode Island 02912cNow at Department of Earth and Planetary Sciences, University of California Davis, One Shields Avenue, Davis, California 95616. Publisher: Seismological Society of America First Online: 13 Feb 2018 Online Issn: 1943-3573 Print Issn: 0037-1106 © Seismological Society of America Bulletin of the Seismological Society of America (2018) 108 (2): 761–780. https://doi.org/10.1785/0120160295 Article history First Online: 13 Feb 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation N. M. Beeler, G. Hirth, T. E. Tullis, C. H. Webb; On the Depth Extent of Coseismic Rupture. Bulletin of the Seismological Society of America 2018;; 108 (2): 761–780. doi: https://doi.org/10.1785/0120160295 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 We investigate the implications of deformation experiments for the coseismic down‐dip extent of rupture in quasi‐dynamic, whole‐cycle earthquake models of a fault for which the depth of the transition between seismic and aseisimic fault slip depends on strain rate. The calculations use a dislocation fault model from Tse and Rice (1986) with a vertical strike‐slip orientation, mode III rupture, and variable along‐strike length. Our reference calculation is the original rheological representation of Tse and Rice with a strain‐rate‐independent transition. The primary calculations use two different representations of a strain‐rate‐dependent transition: (1) between rate‐weakening friction and dislocation creep and (2) between rate‐weakening and rate‐strengthening frictions. For both these cases, when fault strength is high (friction between 0.5 and 0.6) and the transition is sharp, coseismic slip extends a small distance (1–2 km) below the fixed temperature (depth) that is commonly used to define the rheological transition at the plate‐motion rate. Thus, coseismic slip occurs below the depth assumed in seismic hazard models using microseismicity or a chosen fixed‐temperature contour. Though significant coseismic slip occurs below the plate‐rate transition depth, the added moment is <10% of the total. The deep extension is a region that is rheologically distinct; for example, deep coseismic slip can produce a stress increase rather than a stress drop. If friction is smaller, the deepening effect and its contribution to moment are larger. For all representations of the transition, average and surface slip increase with the along‐strike rupture length in a manner consistent with the limited data from natural observations. However, this property is not controlled by the assumed fault rheology; instead, it arises because the stiffness of the fault decreases weakly with fault length, an intrinsic and unrealistic property of the particular crustal scale fault model used. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.