Earth Planets Space, Vol. 60 (No. 2), pp. 123-125, 2008LETTER
Institute of Seismology and Volcanology, Hokkaido University, N10W8 Kita-Ku, Sapporo 080-0610, Japan
(Received June 30, 2007; Revised November 2, 2007; Accepted November 13, 2007; Online published February 19, 2008)
The 2007 Noto Hanto earthquake generated a small tsunami that was recorded at several tide gauge stations along the coast of the Japan Sea. The most important feature of this tsunami is that two waveforms recorded at the Wajima and Noto tide gauge stations, which are located 30 km apart, showed very different later phases—the large later phases recorded at Noto were not observed at Wajima. Numerical simulation of the tsunami indicated that the difference was caused by the shallow water bathymetry around the Noto peninsula. The large tsunami that was amplified at a few tens of kilometers off the north coast of the Noto peninsula propagated towards the Noto tide gauge station, but not towards the Wajima station. This study indicates that the propagation of a tsunami caused by a shallow earthquake beneath a coastal area is significantly affected by the local bathymetry. A comparison of the observed and computed tsunami waveforms indicated that the slip amount of the fault was 0.8 m. The seismic moment of the Noto Hanto earthquake was calculated to be 0.94 × 1019 N m (Mw 6.6).
Key words: 2007 Noto Hanto earthquake, tsunami numerical simulation.