Ground Shaking and Seismic Source Spectra for Large Earthquakes around the Megathrust Fault Offshore of Northeastern Honshu, Japan

Research Article| May 01, 2013 Ground Shaking and Seismic Source Spectra for Large Earthquakes around the Megathrust Fault Offshore of Northeastern Honshu, Japan Lingling Ye; Lingling Ye Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, California 95064 Search for other works by this author on: GSW Google Scholar Thorne Lay; Thorne Lay Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, California 95064 Search for other works by this author on: GSW Google Scholar Hiroo Kanamori Hiroo Kanamori Seismological Laboratory, California Institute of Technology, Pasadena, California 91125 Search for other works by this author on: GSW Google Scholar Bulletin of the Seismological Society of America (2013) 103 (2B): 1221–1241. https://doi.org/10.1785/0120120115 Article history first online: 14 Jul 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Lingling Ye, Thorne Lay, Hiroo Kanamori; Ground Shaking and Seismic Source Spectra for Large Earthquakes around the Megathrust Fault Offshore of Northeastern Honshu, Japan. Bulletin of the Seismological Society of America 2013;; 103 (2B): 1221–1241. doi: https://doi.org/10.1785/0120120115 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 Large earthquake ruptures on or near the plate boundary megathrust fault offshore of northeastern Honshu, Japan, produce variable levels of regional high‐frequency ground shaking. Analyses of 0.1–10 Hz strong ground motion recordings from K‐NET and KiK‐net stations and 0.3–3.0 Hz short‐period recordings from Hi‐net stations establish that the shaking variations result from a combination of differences in seismic source spectra and path attenuation. Eleven earthquakes with Mw 6.0–7.6 are analyzed, including interplate events at different positions on the megathrust within the rupture zone of the 11 March 2011 Tohoku (Mw 9.0) event and nearby intraplate events within the underthrusting Pacific slab. The relative ground shaking for frequencies of 5–10 Hz is strongest for the 7 April 2011 (Mw 7.2) intraslab event near the coast, followed by intraplate events beneath the outer‐trench slope. Decreasing levels of high‐frequency shaking are produced by interplate megathrust events moving from the down‐dip edge of the seismogenic zone to the up‐dip region near the trench. Differential attenuation measurements from averaged spectral ratios of strong‐motion recordings indicate that average path attenuation is lower for events deeper on the megathrust or within the slab below the coast. Empirical Green’s function analysis isolates the source spectra for the passband 0.3–3.0 Hz, indicating higher corner frequencies for intraplate events and deep megathrust events than for shallow megathrust events. Similar differences in average source spectra are found for teleseismic P waves. Depth‐varying source radiation and path attenuation thus account for the high‐frequency shaking for the 2011 Tohoku mainshock originating from the down‐dip portion of the megathrust.Online Material: Figures of spectral ratios, regression of averaged spectral ratios, and stacked spectral ratios. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.