Site‐Effects Model for Central and Eastern North America Based on Peak Frequency and Average Shear‐Wave Velocity

Abstract

Research Article| November 14, 2017 Site‐Effects Model for Central and Eastern North America Based on Peak Frequency and Average Shear‐Wave Velocity Behzad Hassani; Behzad Hassani aDepartment of Earth Sciences, Western University, 1151 Richmond Street, London, Ontario, Canada N6A 5B7, bhassan7@uwo.ca, gmatkinson@aol.com Search for other works by this author on: GSW Google Scholar Gail M. Atkinson Gail M. Atkinson aDepartment of Earth Sciences, Western University, 1151 Richmond Street, London, Ontario, Canada N6A 5B7, bhassan7@uwo.ca, gmatkinson@aol.com Search for other works by this author on: GSW Google Scholar Author and Article Information Behzad Hassani aDepartment of Earth Sciences, Western University, 1151 Richmond Street, London, Ontario, Canada N6A 5B7, bhassan7@uwo.ca, gmatkinson@aol.com Gail M. Atkinson aDepartment of Earth Sciences, Western University, 1151 Richmond Street, London, Ontario, Canada N6A 5B7, bhassan7@uwo.ca, gmatkinson@aol.com Publisher: Seismological Society of America First Online: 14 Nov 2017 Online Issn: 1943-3573 Print Issn: 0037-1106 © Seismological Society of America Bulletin of the Seismological Society of America (2018) 108 (1): 338–350. https://doi.org/10.1785/0120170061 Article history First Online: 14 Nov 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Behzad Hassani, Gail M. Atkinson; Site‐Effects Model for Central and Eastern North America Based on Peak Frequency and Average Shear‐Wave Velocity. Bulletin of the Seismological Society of America 2017;; 108 (1): 338–350. doi: https://doi.org/10.1785/0120170061 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 develop an empirical site‐amplification model for central and eastern North America (CENA) that is parameterized using two site variables: (1) the peak site frequency (⁠fpeak⁠) and (2) the time‐averaged shear‐wave velocity in the upper 30 m (⁠VS30⁠). The model is developed by first deriving empirical site‐amplification terms for seismographic sites in CENA. This is done by analyzing the residuals calculated from ground‐motion amplitude data with respect to a selected regional ground‐motion prediction equation that applies to hard‐rock reference site conditions. An amplification model is then developed that explains the residuals in terms of the two site variables (⁠fpeak and VS30⁠). We consider two alternative cases. In the first case, we assume that VS30 is the main modeling parameter and then model any remaining residual effects in terms of fpeak⁠. In this case, we obtain a frequency‐dependent VS30 scaling term that is similar in form to that obtained in previous studies for sites in western North America (WNA). However, the scaling term is less significant in amplitude for CENA in comparison to that for WNA, suggesting that VS30 is not as strongly indicative of site response. For the second alternative, assuming that fpeak is the main site‐effects parameter, a frequency‐independent VS30 scaling term is obtained for CENA, which is much smaller in amplitude compared to the VS30 scaling effect derived in the first approach. This shows that, using fpeak as the primary site‐effects modeling parameter, we remove most of the VS30 scaling effects that are implied by the data. Finally, we provide recommendations on the effective use of fpeak and VS30 to model site effects in CENA, differentiating between glaciated and nonglaciated sites. Glaciated sites show larger amplifications compared to nonglaciated sites, especially at intermediate‐to‐high frequencies, presumably due to the strong impedance contrast at the base of glaciated sites. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.