Earth Planets Space, Vol. 56 (No. 3), pp. 373-376, 2004LETTER
Yuichiro Tanioka1, Kenji Hirata2, Ryota Hino3, and Toshihiko Kanazawa4
1Institute of Seismology and Volcanology, Hokkaido University, N10W8 Kita-ku, Sapporo 060-0810, Japan
2Deep Sea Research Department, Japan Marine Science and Technology Center, 2-15 Natsuhima-cho, Yokosuka 237-0061, Japan
3Research Center for Prediction of Earthquakes and Volcanic Eruptions, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
4Earthquake Research Institute, The University of Tokyo, 1-1-1 Yayoi, Bunkyou-ku, Tokyo 113-0032, Japan
(Received December 3, 2003; Revised February 17, 2004; Accepted February 29, 2004)
The slip distribution of the 2003 Tokachi-oki earthquake is estimated from the 11 tsunami waveforms recorded at 9 tide gauges in the southern Hokkaido and eastern Tohoku coasts and two ocean bottom tsunami-meters (pressure gauges) off Kamaishi, Tohoku. The largest slip of 4.3 m is estimated on the subfault located off Hiroo. A large slip of 2.1 m is also estimated on the subfault located near Kushiro. The total seismic moment of the 2003 Tokachi-oki earthquake is 1.0 1021 Nm. The slip distribution estimated from the tsunami waveform inversion is similar to the slip distribution deduced by Yamanaka and Kikuchi (2003) from the inversion of the teleseismic body waves. The rupture area of the 2003 Tokachi-oki earthquake is similar to the western part of the rupture area of the 1952 Tokachi-oki earthquake estimated by Hirata et al. (2003).
Key words: The 2003 Tokachi-oki earthquake, slip distribution, tsunami waveform inversion.