Changes in seismicity before and after the 2011 Tohoku earthquake around its southern limit revealed by dense ocean bottom seismic array data

Yukihiro Nakatani, Kimihiro Mochizuki, Masanao Shinohara, Tomoaki Yamada, Ryota Hino, Yoshihiro Ito, Yoshio Murai, Toshinori Sato

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

The southern limit of the 2011 Tohoku earthquake is considered to be located around off Ibaraki. However, it is not well constrained how far south the large slip extended. To give better constraints, we investigated seismicity including small earthquakes before and after the Tohoku earthquake around off Ibaraki using dense ocean bottom seismic array data. We automatically identified epicenters by backprojecting semblance values resulting in a considerable increase in the number of detected events compared with those listed in the catalog based on onshore observation. The results revealed a couple of seismicity-activated region. The largest aftershock also occurred ~30 min after the main shock. Our detailed results suggest that this highly activated seismicity was initiated by the largest aftershock instead of the main shock. It, then, suggests that the large coseismic slip zone of the Tohoku earthquake may not have extended off Ibaraki.

Original languageEnglish
Pages (from-to)1384-1389
Number of pages6
JournalGeophysical Research Letters
Volume42
Issue number5
DOIs
Publication statusPublished - 2015 Mar 16

Keywords

  • OBS
  • backprojection
  • seismicity
  • subducting seamount
  • the 2011 Tohoku earthquake

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

Fingerprint Dive into the research topics of 'Changes in seismicity before and after the 2011 Tohoku earthquake around its southern limit revealed by dense ocean bottom seismic array data'. Together they form a unique fingerprint.

Cite this