Earth Planets Space, Vol. 63 (No. 7), pp. 731-735, 2011
Takeo Ishibe, Kunihiko Shimazaki, Kenji Satake, and Hiroshi Tsuruoka
Earthquake Research Institute, the University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
(Received April 8, 2011; Revised May 28, 2011; Accepted June 2, 2011; Online published September 27, 2011)
Static changes in the Coulomb Failure Function (ΔCFF) forecast an increase in seismicity in and around the Tokyo metropolis after the 2011 off the Pacific coast of Tohoku Earthquake (magnitude 9.0). Among the 30,694 previous events in this region with various depth and focal mechanism, almost 19,000 indicate a significant increase of the ΔCFF, while less than 6,000 indicate a significant decrease. An increase in seismicity is predicted in southwestern Ibaraki and northern Chiba prefectures where intermediate-depth earthquakes occur, and in the shallow crust of the Izu and Hakone regions. A comparison of seismicity before and after the 2011 event reveals that the seismicity in the above regions indeed increased as predicted from the ΔCFF.
Key words: 2011 off the Pacific coast of Tohoku Earthquake, static change in the Coulomb Failure Function (ΔCFF), Tokyo metropolitan area, seismicity.