Decomposing Leftovers: Event, Path, and Site Residuals for a Small‐Magnitude Anza Region GMPE

Abstract

Research Article| July 24, 2018 Decomposing Leftovers: Event, Path, and Site Residuals for a Small‐Magnitude Anza Region GMPE Valerie Sahakian; Valerie Sahakian aEarthquake Science Center, U.S. Geological Survey, 345 Middlefield Road, MS 977, Menlo Park, California 94025, vjs@uoregon.edu Search for other works by this author on: GSW Google Scholar Annemarie Baltay; Annemarie Baltay aEarthquake Science Center, U.S. Geological Survey, 345 Middlefield Road, MS 977, Menlo Park, California 94025, vjs@uoregon.edu Search for other works by this author on: GSW Google Scholar Tom Hanks; Tom Hanks aEarthquake Science Center, U.S. Geological Survey, 345 Middlefield Road, MS 977, Menlo Park, California 94025, vjs@uoregon.edu Search for other works by this author on: GSW Google Scholar Janine Buehler; Janine Buehler bScripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92039 Search for other works by this author on: GSW Google Scholar Frank Vernon; Frank Vernon bScripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92039 Search for other works by this author on: GSW Google Scholar Debi Kilb; Debi Kilb bScripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92039 Search for other works by this author on: GSW Google Scholar Norman Abrahamson Norman Abrahamson cCivil and Environmental Engineering, UC Berkeley, 447 Davis Hall, Berkeley, California 94720 Search for other works by this author on: GSW Google Scholar Author and Article Information Valerie Sahakian aEarthquake Science Center, U.S. Geological Survey, 345 Middlefield Road, MS 977, Menlo Park, California 94025, vjs@uoregon.edu Annemarie Baltay aEarthquake Science Center, U.S. Geological Survey, 345 Middlefield Road, MS 977, Menlo Park, California 94025, vjs@uoregon.edu Tom Hanks aEarthquake Science Center, U.S. Geological Survey, 345 Middlefield Road, MS 977, Menlo Park, California 94025, vjs@uoregon.edu Janine Buehler bScripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92039 Frank Vernon bScripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92039 Debi Kilb bScripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92039 Norman Abrahamson cCivil and Environmental Engineering, UC Berkeley, 447 Davis Hall, Berkeley, California 94720 Publisher: Seismological Society of America First Online: 24 Jul 2018 Online Issn: 1943-3573 Print Issn: 0037-1106 © Seismological Society of America Bulletin of the Seismological Society of America (2018) 108 (5A): 2478–2492. https://doi.org/10.1785/0120170376 Article history First Online: 24 Jul 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Valerie Sahakian, Annemarie Baltay, Tom Hanks, Janine Buehler, Frank Vernon, Debi Kilb, Norman Abrahamson; Decomposing Leftovers: Event, Path, and Site Residuals for a Small‐Magnitude Anza Region GMPE. Bulletin of the Seismological Society of America 2018;; 108 (5A): 2478–2492. doi: https://doi.org/10.1785/0120170376 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 Ground‐motion prediction equations (GMPEs) are critical elements of probabilistic seismic hazard analysis (PSHA), as well as for other applications of ground motions. To isolate the path component for the purpose of building nonergodic GMPEs, we compute a regional GMPE using a large dataset of peak ground accelerations (PGAs) from small‐magnitude earthquakes (⁠0.5≤M≤4.5 with >10,000 events, yielding ∼120,000 recordings) that occurred in 2013 centered around the ANZA seismic network (hypocentral distances ≤180 km⁠) in southern California. We examine two separate methods of obtaining residuals from the observed and predicted ground motions: a pooled ordinary least‐squares model and a mixed‐effects maximum‐likelihood model. Whereas the former is often used by the broader seismological community, the latter is widely used by the ground‐motion and engineering seismology community. We confirm that mixed‐effects models are the preferred and most statistically robust method to obtain event, path, and site residuals and discuss the reasoning behind this. Our results show that these methods yield different consequences for the uncertainty of the residuals, particularly for the event residuals. Finally, our results show no correlation (correlation coefficient [CC] <0.03⁠) between site residuals and the classic site‐characterization term VS30⁠, the time‐averaged shear‐wave velocity in the top 30 m at a site. We propose that this is due to the relative homogeneity of the site response in the region and perhaps due to shortcomings in the formulation of VS30 and suggest applying the provided PGA site correction terms to future ground‐motion studies for increased accuracy. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.