Joint Inversion was made using teleseismic data (provided by IRIS-DMC) and Strong ground motion data (provided by NIED)
On Sep. 26, 2003 (JST), a reverse-faulting earthquake (Mjma = 6.1) occurred in off Tokachi, Hokkaido, Japan , where the Pacific plate subductes west beneath the northeastern Japan island arc at rate of about 80 mm/year. The depth of hypocenter and focal mechanism show that this earthquake is a typical inter-plate earthquake. I retrieved teleseismic body waves (P-waves) and strong ground motion data recorded at IRIS-dmc stations and K-net (NIED) via Internet, respectively.
The seismic moment Mo = 1.5 x 10**20 Nm (Mw 8.1);
The source duration T = 55 s;
(strike, dip, rake) = (249, 15, 130)
Hypocenter: (Lat. = 41.78N, Lon. = 144.08E, depth = 15 km).
[The epicenter of the main-shock was determined by JMA]
Maximum slip = 6.2(m)
(Yagi, IISEE, BRI, 2003)
Figure : Hypocenter determined by Hi-net (NIED).
Figure : Snapshots of cumulative dislocation.
Figure : (upper left) Focal mechanism; (upper right) Total moment-rate function; (lower) Distribution of coseismic slip. Star indicates the location of the initial break.
Figure : Comparison of the observed waveform (Black) with the calculated waveform (Red). The numbers below the station code indicate maximum amplitude in microns. The start time of the traces is lined-up at 10 (s) before the P-wave arrival.
Figure : Comparison of the observed waveform (Black) with the calculated waveform (Red). The numbers below the station code indicate maximum amplitude in cm/sec. The start time of the traces is lined-up at 5 (s) before the P-wave arrival.