Abstract

Along the northern Kuril trench, a great interplate earthquake occurred in November 2006 followed by an outer-rise normal fault event in January 2007. Surface wave magnitudes (MS 7.8 and 8.2) indicate that the 2007 event was larger, while the Global CMT solutions (Mw 8.3 and 8.1) indicate that the 2006 event was larger. Tsunamis from both events were recorded at tide gauge stations in Japan, Russia, and the United States, as well as deep-ocean assessment and reporting of tsunamis (DART) systems and cabled tsunami sensors installed on deep-ocean bottom. Inversion of 52 tsunami waveforms indicates that the 2006 tsunami source was about 200 km long, extending from the epicenter to northeast. The largest slips of 4–7 m are estimated on the northeastern subfaults. For the 2007 event, inversion of 32 waveforms shows that the tsunami source was about 120 km long with the largest slip of 3.5 m on the northeastern subfault. The agreements between the observed and synthetic tsunami waveforms are generally good for both events, not only within the inversion time windows but also for the later phases, which were not used in inversions. The slip distributions yield the seismic moment of forumla (Mw 8.1) for the 2006 event and forumla (Mw 7.9) for the 2007 event. The seismic moment of the 2006 event was larger than the 2007 event, from comparison of tsunami data, regardless of fault model.

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