Spatial and Temporal Variations in Coda Attenuation Associated with the 2011 Off the Pacific Coast of Tohoku, Japan (Mw 9) Earthquake

Abstract

Research Article| May 01, 2013 Spatial and Temporal Variations in Coda Attenuation Associated with the 2011 Off the Pacific Coast of Tohoku, Japan (Mw 9) Earthquake Simanchal Padhy; Simanchal Padhy Earthquake Research Institute, The University of Tokyo, 1‐1‐1 Yayoi, Bunkyo‐ku, 113‐0032 Tokyo, Japanpadhy@eri.u-tokyo.ac.jpshunsuke@eri.u-tokyo.ac.jpteito@eri.u-tokyo.ac.jpmaeda@eri.u-tokyo.ac.jpfurumura@eri.u-tokyo.ac.jp *Also at Council of Scientific and Industrial Research (CSIR), National Geophysical Research Institute, Uppal Road, Hyderabad‐500007, India. †Also at Center for Integrated Disaster Information Research, Interfaculty Initiative in Information Studies, The University of Tokyo, 7‐3‐1 Hongo, Bunkyo‐ku, 113‐0033 Tokyo, Japan. Search for other works by this author on: GSW Google Scholar Shunsuke Takemura; Shunsuke Takemura Earthquake Research Institute, The University of Tokyo, 1‐1‐1 Yayoi, Bunkyo‐ku, 113‐0032 Tokyo, Japanpadhy@eri.u-tokyo.ac.jpshunsuke@eri.u-tokyo.ac.jpteito@eri.u-tokyo.ac.jpmaeda@eri.u-tokyo.ac.jpfurumura@eri.u-tokyo.ac.jp ‡Now at Earthquake Research Lab, Yokohama City University, Yokohama 236‐0027, Japan. Search for other works by this author on: GSW Google Scholar Teito Takemoto; Teito Takemoto Earthquake Research Institute, The University of Tokyo, 1‐1‐1 Yayoi, Bunkyo‐ku, 113‐0032 Tokyo, Japanpadhy@eri.u-tokyo.ac.jpshunsuke@eri.u-tokyo.ac.jpteito@eri.u-tokyo.ac.jpmaeda@eri.u-tokyo.ac.jpfurumura@eri.u-tokyo.ac.jp Search for other works by this author on: GSW Google Scholar Takuto Maeda; Takuto Maeda Earthquake Research Institute, The University of Tokyo, 1‐1‐1 Yayoi, Bunkyo‐ku, 113‐0032 Tokyo, Japanpadhy@eri.u-tokyo.ac.jpshunsuke@eri.u-tokyo.ac.jpteito@eri.u-tokyo.ac.jpmaeda@eri.u-tokyo.ac.jpfurumura@eri.u-tokyo.ac.jp †Also at Center for Integrated Disaster Information Research, Interfaculty Initiative in Information Studies, The University of Tokyo, 7‐3‐1 Hongo, Bunkyo‐ku, 113‐0033 Tokyo, Japan. Search for other works by this author on: GSW Google Scholar Takashi Furumura Takashi Furumura Earthquake Research Institute, The University of Tokyo, 1‐1‐1 Yayoi, Bunkyo‐ku, 113‐0032 Tokyo, Japanpadhy@eri.u-tokyo.ac.jpshunsuke@eri.u-tokyo.ac.jpteito@eri.u-tokyo.ac.jpmaeda@eri.u-tokyo.ac.jpfurumura@eri.u-tokyo.ac.jp †Also at Center for Integrated Disaster Information Research, Interfaculty Initiative in Information Studies, The University of Tokyo, 7‐3‐1 Hongo, Bunkyo‐ku, 113‐0033 Tokyo, Japan. Search for other works by this author on: GSW Google Scholar Bulletin of the Seismological Society of America (2013) 103 (2B): 1411–1428. https://doi.org/10.1785/0120120026 Article history first online: 14 Jul 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Simanchal Padhy, Shunsuke Takemura, Teito Takemoto, Takuto Maeda, Takashi Furumura; Spatial and Temporal Variations in Coda Attenuation Associated with the 2011 Off the Pacific Coast of Tohoku, Japan (Mw 9) Earthquake. Bulletin of the Seismological Society of America 2013;; 103 (2B): 1411–1428. doi: https://doi.org/10.1785/0120120026 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 The spatial and temporal variations of coda attenuation (⁠⁠) were studied in the source region of the 2011 Off the Pacific Coast of Tohoku, Japan (Mw 9) earthquake. The values were determined from the amplitude decay rate of the S‐wave coda in narrower overlapping frequency bands in the range f=1.0–24 Hz, based on a single isotropic scattering model for more than 400 earthquakes (MJMA 3∼6.5) in the region recorded in a period from January 2005 to August 2011, including pre‐ and postseismic period. Our estimates of the spatially averaged value, in f=1.0–24 Hz, is almost stable with small variations (<10%) during the preseismic period, which is in good agreement with that estimated by former studies in the area of northeast Japan. We found that the value of increases by about 10%–16% after the 2011 Tohoku event in f=1.25–3.5 Hz in some stations of northern Japan, which is confirmed by a statistical t‐test at 99.9% confidence level. The change in is spatially limited to the rupture zone, while other paths remain nearly unaffected, suggesting local changes of scattering properties in the vicinity of the Tohoku‐Oki source volume. This change may be attributed to an increase in the density of open microcracks in the mainshock source volume (such as due to increase in stress induced by the 2011 event) and probably the fluid content in fractures in the rocks. A model of heterogeneity due to coseismically opened cracks (dominant scale length of a=0.6–1.8 km in f=1.25–3.5 Hz) enhanced by increased stress change possibly controls the increased after the 2011 event in the source rupture region. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.