Earth Planets Space, Vol. 60 (No. 2), pp. 133-138, 2008LETTER
Ikuo Abe1, Kazuhisa Goto1, Fumihiko Imamura1, and Katsuyoshi Shimizu2
1Disaster Control Research Center, Graduate School of Engineering, Tohoku University, Aoba 06-6-11-1106, Aramaki, Sendai 980-8579, Japan
2Marine Information Division, Port and Airport Research Institute, 3-1-1 Nagase, Yokosuka 239-0826, Japan
(Received June 30, 2007; Revised September 18, 2007; Accepted October 4, 2007; Online published February 19, 2008)
We conducted a numerical analysis of the tsunami generated by the 2007 Noto Hanto Earthquake (Mj = 6.9) that occurred on 25 March 2007 near the Noto Peninsula on the northwest coast of Honshu Island, Japan. Our numerical simulation reproduced well the behaviors of the tsunami as recorded at the Wajima tidal observatory and showed that the computed tsunami arrived in Toyama Bay more than 1 h after the earthquake. However, a crew of a small boat in the bay felt the shock and, despite calm weather conditions, their boat capsized just 3 min after the earthquake. Although abnormal tidal surges were recorded at several locations around Toyama Bay, the timing of these is inconsistent with the surges being a direct result of the tsunami generated at the source area of the earthquake. We used "backward wave propagation analysis" to estimate the likely source area of the abnormal tidal surges in the bay and carried out the a simulation of landslide-induced tsunami. Our conclusion is that these abnormal tidal surges were likely caused by a submarine landslide on the steep sea floor on the western side of Toyama Bay.
Key words: The 2007 Noto Hanto Earthquake, tsunami, Toyama Bay, abnormal wave.