Earth Planets Space, Vol. 58 (No. 1), pp. 57-62, 2006LETTER
Reiji Kobayashi, Shin'ichi Miyazaki, and Kazuki Koketsu
Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
(Received August 24, 2005; Revised November 23, 2005; Accepted November 28, 2005; Online published January 27, 2006)
We simultaneously inverted strong motion and 1-Hz GPS data recorded during the 2005 west off Fukuoka prefecture earthquake (MJMA 7.0) for its source process. The data at a GPS station near the source region provided strong constraint on the fault geometry and asperity area. The resultant slip distribution suggests a single asperity close to the Genkai island, where many houses were severely damaged. The maximum slip is 1.4 m, and the total seismic moment is 1.0 × 1019 Nm (MW 6.6). We also inverted strong motion data recorded during the largest aftershock (MJMA 5.8). The resultant slip distribution shows two asperities on the fault plane. The maximum slip in the major asperity is 0.12 m and the total seismic moment is 2.0 × 1017 Nm (MW 5.5). The main shock and largest aftershock may cause stress change on the Kego fault, which is a major fault running through the city of Fukuoka.
Key words: The 2005 west off Fukuoka prefecture earthquake, source process, strong motion, 1-Hz GPS data, joint inversion.