Coseismic slip distribution of the 2005 off Miyagi earthquake (M7.2) estimated by inversion of teleseismic and regional seismograms

  • Yaginuma Tadashi
    Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University
  • Okada Tomomi
    Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University
  • Yagi Yuji
    Graduate School of Life and Environmental Sciences,University of Tsukuba
  • Matsuzawa Toru
    Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University
  • Umino Norihito
    Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University
  • Hasegawa Akira
    Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University

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Description

A large earthquake (M7.2) occurred along the plate boundary offMiyagi Prefecture (Miyagi-Oki), northeastern Japan, on August 16, 2005. In this area, large earthquakes (-M7.5) have occurred repeatedly at intervals of about 37 years, and more than 27 years have passed since the last event occurred. To estimate the relationship between this earthquake and the previous events, we determined coseismic slip distribution by this 2005 Miyagi-Oki earthquake by adopting the seismic waveform inversion method of Yagi et al. (2004) and compared it with that of the previous 1978 Miyagi-Oki earthquake. We performed two cases of the inversions; inversion using only far-field seismograms and that using far-field seismograms and local seismograms simultaneously. Both results show that a large slip occurred near the hypocenter and rupture extended to the westward deeper portion. Considering that the rupture area of the 2005 event partly overlapped with the southeastern part of that of the 1978 event, suggests this result the possibility that plural asperities exist which cause the sequence of Miyagi-Oki earthquakes and that the 2005 event ruptured one of such asperities, although the previous 1978 event ruptured all the asperities at one time.

Journal

  • Earth, Planets and Space

    Earth, Planets and Space 58 (12), 1549-1554, 2006

    Society of Geomagnetism and Earth, Planetary and Space Sciences, The Seismological Society of Japan, The Volcanological Society of Japan , The Geodetic Society of Japan , The Japanese Society for Planetary Sciences

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