Seismic and geodetic evidence for extensive, long-lived fault damage zones

Abstract

Research Article| April 01, 2009 Seismic and geodetic evidence for extensive, long-lived fault damage zones Elizabeth S. Cochran; Elizabeth S. Cochran 1Department of Earth Sciences, University of California–Riverside, Riverside, California 92521, USA Search for other works by this author on: GSW Google Scholar Yong-Gang Li; Yong-Gang Li 2Department of Earth Sciences, University of Southern California, Los Angeles, California 90089, USA Search for other works by this author on: GSW Google Scholar Peter M. Shearer; Peter M. Shearer 3Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California–San Diego, La Jolla, California 92093, USA Search for other works by this author on: GSW Google Scholar Sylvain Barbot; Sylvain Barbot 3Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California–San Diego, La Jolla, California 92093, USA Search for other works by this author on: GSW Google Scholar Yuri Fialko; Yuri Fialko 3Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California–San Diego, La Jolla, California 92093, USA Search for other works by this author on: GSW Google Scholar John E. Vidale John E. Vidale 4Department of Earth and Space Sciences, University of Washington, Seattle, Washington 98195, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Elizabeth S. Cochran 1Department of Earth Sciences, University of California–Riverside, Riverside, California 92521, USA Yong-Gang Li 2Department of Earth Sciences, University of Southern California, Los Angeles, California 90089, USA Peter M. Shearer 3Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California–San Diego, La Jolla, California 92093, USA Sylvain Barbot 3Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California–San Diego, La Jolla, California 92093, USA Yuri Fialko 3Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California–San Diego, La Jolla, California 92093, USA John E. Vidale 4Department of Earth and Space Sciences, University of Washington, Seattle, Washington 98195, USA Publisher: Geological Society of America Received: 17 Jul 2008 Revision Received: 10 Nov 2008 Accepted: 16 Nov 2008 First Online: 02 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2009 Geological Society of America Geology (2009) 37 (4): 315–318. https://doi.org/10.1130/G25306A.1 Article history Received: 17 Jul 2008 Revision Received: 10 Nov 2008 Accepted: 16 Nov 2008 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Elizabeth S. Cochran, Yong-Gang Li, Peter M. Shearer, Sylvain Barbot, Yuri Fialko, John E. Vidale; Seismic and geodetic evidence for extensive, long-lived fault damage zones. Geology 2009;; 37 (4): 315–318. doi: https://doi.org/10.1130/G25306A.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 SocietyGeology Search Advanced Search Abstract During earthquakes, slip is often localized on preexisting faults, but it is not well understood how the structure of crustal faults may contribute to slip localization and energetics. Growing evidence suggests that the crust along active faults undergoes anomalous strain and damage during large earthquakes. Seismic and geodetic data from the Calico fault in the eastern California shear zone reveal a wide zone of reduced seismic velocities and effective elastic moduli. Using seismic traveltimes, trapped waves, and interferometric synthetic aperture radar observations, we document seismic velocities reduced by 40%– 50% and shear moduli reduced by 65% compared to wall rock in a 1.5-km-wide zone along the Calico fault. Observed velocity reductions likely represent the cumulative mechanical damage from past earthquake ruptures. No large earthquake has broken the Calico fault in historic time, implying that fault damage persists for hundreds or perhaps thousands of years. These findings indicate that faults can affect rock properties at substantial distances from primary fault slip surfaces, and throughout much of the seismogenic zone, a result with implications for the amount of energy expended during rupture to drive cracking and yielding of rock and development of fault systems. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.