The Case for Mean Rupture Distance in Ground‐Motion Estimation

Research Article| August 07, 2018 The Case for Mean Rupture Distance in Ground‐Motion Estimation Eric M. Thompson; Eric M. Thompson aU.S. Geological Survey, Denver Federal Center, P.O. Box 25046, MS966, Denver, Colorado 80225, emthompson@usgs.gov Search for other works by this author on: GSW Google Scholar Annemarie S. Baltay Annemarie S. Baltay bU.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar Author and Article Information Eric M. Thompson aU.S. Geological Survey, Denver Federal Center, P.O. Box 25046, MS966, Denver, Colorado 80225, emthompson@usgs.gov Annemarie S. Baltay bU.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Publisher: Seismological Society of America First Online: 07 Aug 2018 Online Issn: 1943-3573 Print Issn: 0037-1106 © Seismological Society of America Bulletin of the Seismological Society of America (2018) 108 (5A): 2462–2477. https://doi.org/10.1785/0120170306 Article history First Online: 07 Aug 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Eric M. Thompson, Annemarie S. Baltay; The Case for Mean Rupture Distance in Ground‐Motion Estimation. Bulletin of the Seismological Society of America 2018;; 108 (5A): 2462–2477. doi: https://doi.org/10.1785/0120170306 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 This article advocates for the use of mean rupture distances that we contend are more physically representative of the distance to an earthquake and are simpler than minimum distances. Many current ground‐motion models (GMMs) rely on numerous modifications of minimum rupture distances to accurately model near‐source ground motions. These modifications, that include additional distance definitions and saturation terms, result in complicated functional forms and are often not easily understood on a seismological basis, such as the magnitude‐dependent near‐fault saturation term. The use of mean distance represents the location of a station in relation to the entire rupture plane and results in a simpler, more physically meaningful GMM that models near‐source ground motion as accurately as other GMMs that have more inputs and more complex functional forms. We demonstrate the use of mean distance by developing a GMM for shallow‐crustal earthquakes with the Next Generation Attenuation‐West2 (NGA‐West2) project database. Specifically, we use the generalized mean distance, also known as the power mean, in which the power varies with frequency. We show that this new GMM fits the NGA‐West2 database as well as the NGA‐West2 GMMs and exhibits similar near‐source amplitude scaling. An additional benefit of mean distance is that it can provide a mechanism to account for spatially variable slip. We prospectively validate this GMM against the 2016 M 7.8 Kaikōura, New Zealand, earthquake, which was not used in model development. To better understand the magnitude dependence of geometrical spreading, we employ a simple conceptual model based on fundamental principles to show that the GMM is consistent with common seismological understanding. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.