Ground Motion and Intraevent Variability from 3D Deterministic Broadband (0–7.5 Hz) Simulations along a Nonplanar Strike‐Slip Fault

Research Article| November 13, 2018 Ground Motion and Intraevent Variability from 3D Deterministic Broadband (0–7.5 Hz) Simulations along a Nonplanar Strike‐Slip Fault Kyle B. Withers; Kyle B. Withers aDepartment of Geological Science, 5500 Campanile Drive, San Diego State University, San Diego, California 92182, kwithers@usgs.govkbolsen@mail.sdsu.edusday@mail.sdsu.eduzshi@mail.sdsu.edubNow at U.S. Geological Survey, Geologic Hazards Science Center, 1711 Illinois Street, Golden, Colorado 80401.cAlso at Institute of Geophysics and Planetary Physics, 9500 Gilman Drive, University of California, San Diego, La Jolla, California 92093. Search for other works by this author on: GSW Google Scholar Kim B. Olsen; Kim B. Olsen aDepartment of Geological Science, 5500 Campanile Drive, San Diego State University, San Diego, California 92182, kwithers@usgs.govkbolsen@mail.sdsu.edusday@mail.sdsu.eduzshi@mail.sdsu.edu Search for other works by this author on: GSW Google Scholar Steven M. Day; Steven M. Day aDepartment of Geological Science, 5500 Campanile Drive, San Diego State University, San Diego, California 92182, kwithers@usgs.govkbolsen@mail.sdsu.edusday@mail.sdsu.eduzshi@mail.sdsu.edu Search for other works by this author on: GSW Google Scholar Zheqiang Shi Zheqiang Shi aDepartment of Geological Science, 5500 Campanile Drive, San Diego State University, San Diego, California 92182, kwithers@usgs.govkbolsen@mail.sdsu.edusday@mail.sdsu.eduzshi@mail.sdsu.edudNow at Tokio Marine Technologies, LLC, 2160 Satellite Boulevard 400, Duluth, Georgia 30097. Search for other works by this author on: GSW Google Scholar Author and Article Information Kyle B. Withers aDepartment of Geological Science, 5500 Campanile Drive, San Diego State University, San Diego, California 92182, kwithers@usgs.govkbolsen@mail.sdsu.edusday@mail.sdsu.eduzshi@mail.sdsu.edubNow at U.S. Geological Survey, Geologic Hazards Science Center, 1711 Illinois Street, Golden, Colorado 80401.cAlso at Institute of Geophysics and Planetary Physics, 9500 Gilman Drive, University of California, San Diego, La Jolla, California 92093. Kim B. Olsen aDepartment of Geological Science, 5500 Campanile Drive, San Diego State University, San Diego, California 92182, kwithers@usgs.govkbolsen@mail.sdsu.edusday@mail.sdsu.eduzshi@mail.sdsu.edu Steven M. Day aDepartment of Geological Science, 5500 Campanile Drive, San Diego State University, San Diego, California 92182, kwithers@usgs.govkbolsen@mail.sdsu.edusday@mail.sdsu.eduzshi@mail.sdsu.edu Zheqiang Shi aDepartment of Geological Science, 5500 Campanile Drive, San Diego State University, San Diego, California 92182, kwithers@usgs.govkbolsen@mail.sdsu.edusday@mail.sdsu.eduzshi@mail.sdsu.edudNow at Tokio Marine Technologies, LLC, 2160 Satellite Boulevard 400, Duluth, Georgia 30097. Publisher: Seismological Society of America First Online: 13 Nov 2018 Online Issn: 1943-3573 Print Issn: 0037-1106 © Seismological Society of America Bulletin of the Seismological Society of America (2019) 109 (1): 229–250. https://doi.org/10.1785/0120180006 Article history First Online: 13 Nov 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Kyle B. Withers, Kim B. Olsen, Steven M. Day, Zheqiang Shi; Ground Motion and Intraevent Variability from 3D Deterministic Broadband (0–7.5 Hz) Simulations along a Nonplanar Strike‐Slip Fault. Bulletin of the Seismological Society of America 2018;; 109 (1): 229–250. doi: https://doi.org/10.1785/0120180006 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 model deterministic broadband (0–7.5 Hz) ground motion from an Mw 7.1 bilateral strike‐slip earthquake scenario with dynamic rupture propagation along a rough‐fault topography embedded in a medium including small‐scale velocity and density perturbations. Spectral accelerations (SAs) at periods 0.2–3 s and Arias intensity durations show a similar distance decay (at the level of 1–2 interevent standard deviations above the median) when compared to Next Generation Attenuation‐West2 (NGA)‐West2 ground‐motion prediction equations (GMPEs) using a Q(f ) power‐law exponent of 0.6–0.8 above 1 Hz in models with a minimum VS of 750 m/s⁠. With a trade‐off from Q(f )⁠, the median ground motion is slightly increased by scattering from statistical models of small‐scale heterogeneity with standard deviation (⁠σ⁠) of the perturbations at the lower end of the observed range (5%) but reduced by scattering attenuation at the upper end (10%) when using a realistic 3D background velocity model. The ground‐motion variability is strongly affected by the addition of small‐scale media heterogeneity, reducing otherwise large values of intraevent standard deviation closer to those of empirical observations. These simulations generally have intraevent standard deviations for SAs lower than the GMPEs for the modeled bandwidth, with an increasing trend with distance (most pronounced in low‐to‐moderate scattering media) near the level of observations at distances greater than 35 km from the fault. Durations for the models follow the same increasing trend with distance, in which σ ∼ 5% produces the best match to GMPE values. We find that a 3D background‐velocity model reduces the pulse period into the expected range by breaking up coherent waves from directivity, generating a lognormal distribution of ground‐motion residuals. These results indicate that a strongly heterogeneous medium is needed to produce realistic deterministic broadband ground motions. Finally, the addition of a thin surficial layer with low, frequency‐independent Q in the model (with a minimum VS of 750 m/s⁠) controls the high‐frequency decay in energy, as measured by the parameter κ⁠, that may be necessary to include as simulations continue to extend to higher frequencies. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.