Bends and Ends of Surface Ruptures

Abstract

Research Article| October 10, 2017 Bends and Ends of Surface Ruptures Glenn P. Biasi; Glenn P. Biasi aUniversity of Nevada, Reno, Nevada Seismological Laboratory, MS‐174, Reno, Nevada 89557, [e-mail]@unr.edu Search for other works by this author on: GSW Google Scholar Steven G. Wesnousky Steven G. Wesnousky bUniversity of Nevada, Reno, Center for Neotectonic Studies, MS‐169, Reno, Nevada 89557cAlso at University of Nevada, Reno, Nevada Seismological Laboratory, MS‐174, Reno, Nevada 89557. Search for other works by this author on: GSW Google Scholar Author and Article Information Glenn P. Biasi aUniversity of Nevada, Reno, Nevada Seismological Laboratory, MS‐174, Reno, Nevada 89557, [e-mail]@unr.edu Steven G. Wesnousky bUniversity of Nevada, Reno, Center for Neotectonic Studies, MS‐169, Reno, Nevada 89557cAlso at University of Nevada, Reno, Nevada Seismological Laboratory, MS‐174, Reno, Nevada 89557. Publisher: Seismological Society of America First Online: 10 Oct 2017 Online Issn: 1943-3573 Print Issn: 0037-1106 Bulletin of the Seismological Society of America (2017) 107 (6): 2543–2560. https://doi.org/10.1785/0120160292 Article history First Online: 10 Oct 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Glenn P. Biasi, Steven G. Wesnousky; Bends and Ends of Surface Ruptures. Bulletin of the Seismological Society of America 2017;; 107 (6): 2543–2560. doi: https://doi.org/10.1785/0120160292 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 To improve the empirical basis for estimating the likely length of future earthquake ruptures on mapped active faults, we measure map‐scale complexities including fault bends, discontinuous rupture, overlaps, and fault‐to‐fault rupture from 67 historical ruptures and analyze the measurements for statistical relationships relevant to seismic hazard analysis. We observe that angles of bends at the ends of surface ruptures on strike‐slip faults are systematically larger than interior bends (IBs), whereas corresponding interior and ending populations are similar for dip‐slip events. The probability of a strike‐slip rupture passing a bend decreases systematically with increasing bend angle roughly as PR=3.1−0.083×A⁠, in which PR is the passing ratio and A is the bend angle, with values ranging between 5° and 30°. The regression shows the likelihood of a strike‐slip rupture propagating through a bend of 25° is about 50%. The maximum IB angles through which ruptures propagate, and the net orientation differences of fault segments at the end of ruptures, may be explained to first order by changes in frictional resistance due to changes in fault strike in a locally constant orientation of regional stress. The average curvature of a fault rupture is defined by dividing the sum of absolute values of bends in the rupture by rupture length. Median and 95% curvatures of strike‐slip ruptures are 0.5°/km and 1.5°/km⁠, respectively; corresponding values for dip‐slip ruptures are 1.6°/km and 5.6°/km⁠, respectively. We find that most fault‐to‐fault rupture connections jump to a fault of like mechanism, such as strike slip to strike slip. Only two strike‐slip ruptures out of a total of 42 jump to reverse structures and continue for a significant distance. Results here provide empirical data to support study of the dynamics of fault rupture and to improve rupture‐length estimates for use in seismic hazard assessment. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.