- Article
- Published:
Rupture process of the July 2003 northern Miyagi earthquake sequence, NE Japan, estimated from double-difference hypocenter locations
Earth, Planets and Space volume 55, pages 741–750 (2003)
Abstract
A shallow M6.4 inland earthquake occurred on July 26, 2003 in the northern part of Miyagi Prefecture, northeastern Japan. We precisely located hypocenters of this event, its foreshocks and aftershocks by applying the double-difference method to data from temporal seismic stations and the seismic stations of Tohoku Univ., JMA and Hi-net. Aftershocks thus located are distributed in an area with about 15 km × 15 km and their depths range from 2 to 13 km. They are distributed along a curved plane dipping westward to north-westward with a dip of about 50 degrees. Its strike is about N-S in the northern part and about NNE-SSW in the southern part. The M5.6 foreshock, which occurred 7 hours before the main shock, is located near the center of the whole aftershock area at which the strike of the aftershock alignment changes abruptly. Aftershocks for the M5.6 foreshock are distributed in the southern part of the whole aftershock area. The main shock is located in the southern part of the aftershock area. It occurred near the edge of the area of aftershocks for the M5.6 foreshock. Aftershocks following the main shock are mainly distributed in the northern part of the aftershock area. The largest aftershock (M5.5) is located at the northern end of the whole aftershock area. After the occurrence of the main shock, few aftershocks occurred in the area of aftershocks for the M5.6 foreshock. We also determined fault plane solutions for the events that occurred during the sequence from the M5.6 foreshock to the largest (M5.5) aftershock. The spatial variation of focal mechanism is consistent with the curved geometry of the fault plane estimated from the aftershock distribution.
References
Dreger, D. S. and D. V. Helmberger, Determination of source parameters at regional distances with single station or sparse network data, Journal of Geophysical Research, 98, 8107–8125, 1993.
Fukuyama, E., M. Ishida, D. S. Dreger, and H. Kawai, Automated seismic moment tensor determination by using on-line broad band seismic waveforms, J. Seism. Soc. Japan (Zisin), 51, 149–156, 1998 (in Japanese with English abstract).
Geological Survey of Japan, Geological map—off Kinkasan—, Geological Survey of Japan, Tsukuba, 1990.
Geological Survey of Japan, Geological Map—Ishinomaki, second edition, Geological Survey of Japan, Tsukuba, 1992.
Hasegawa, A., N. Umino, and A. Takagi, Double-planed structure of the deep seismic zone in the northeastern Japan arc, Tectonophysics, 47, 43–58, 1978.
Hasegawa, A., A. Yamamoto, N. Umino, S. Miura, S. Horiuchi, D. Zhao, and H. Sato, Seismic activity and deformation process of the crust within the overriding plate in the northeastern Japan subduction zone, Tectonophysics, 319, 225–239, 2000.
Mendoza, C. and S. H. Hartzell, Aftershock patterns and main shock faulting, Bulletin of Seismological Society of America, 78, 1438–1449, 1988.
Okada, T., N. Umino, Y. Ito, T. Matsuzawa, A. Hasegawa, and M. Kamiyama, Source processes of 15 September 1998 M5.0 Sendai, NE Japan, earthquake and its M3.8 foreshock by waveform inversion, Bulletin of Seismological Society of America, 91, 1607–1618, 2001a.
Okada, T., T. Yamashita, T. Nakayama, T. Matsuzawa, A. Hasegawa, and F. Tajima, Determination of moment tensors using Tohoku University’s broad-band seismic network, Programme and Abstracts for Fall meeting of Seismlogical Society of Japan, P105, 2001b (in Japanese).
Okada, T., T. Matsuzawa, and A. Hasegawa, Comparison of source areas of M4.8 +/− 0.1 repeating earthquakes off Kamaishi, NE Japan—Are asperities persistent features?, Earth and Planetary Science Letters, 213, 361–374, 2003.
Saikia, C. K., Modified frequency-wavenumber algorithm for regional seismograms using Filon’s quadrature: modeling of Lg waves in eastern North America, Geophysical Journal International, 118, 142–158, 1994.
Sato, H., T. Imaizumi, T. Yoshida, H. Ito, and A. Hasegawa, Tectonic evolution and deep to shallow geometry of Nagamachi-Rifu Active Fault System, NE Japan, Earth Planets Space, 54, 1039–1043, 2002.
Tajima, F. and H. Kanamori, Global survey of aftershock area expansion patterns, Physics of Earth and Planerary Interiors, 40, 77–134, 1985.
Umino, N., T. Okada, J. Nakajima, S. Hori, T. Kono, T. Nakayama, N. Uchida, J. Shimizu, J. Suganomata, G. Shantha, K. Nida, Y Yabe, K. Sakoda, N. Sato, M. Ito, A. Hasegawa, Y. Asano, A. Hasemi, T. Demachi, and Y. Yajima, Hypocenter and focal mechanism distribution of aftershocks of July 26, 2003, M6.2 northern Miyagi earthquake revealed by temporary observations, J. Seism. Soc. Japan (Zisin), 2003 (in press) (in Japanese with English abstract).
Waldhauser, F., HypoDD: A computer program to compute double-difference hypocenter locations, US Geol Surv Open File Rep, 01–113, 25 pp., 2001.
Waldhauser, F. and W. L. Ellsworth, A double-difference earthquake location algorithm: method and application to the Northern Hayward fault, Bulletin of Seismological Society of America, 90, 1353–1368, 2000.
Yagi, Y., Y. Ito, Y. Asano, and S. Sekine, Fore-shock, Main-shock and the largest aftershock associated with the July 26 2003 Miyagi-ken-hokubu, Japan, earthquake, Abstract for the 2003 Fall Meeting of Seismological Society of Japan, A086, 2003.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Okada, T., Umino, N. & Hasegawa, A. Rupture process of the July 2003 northern Miyagi earthquake sequence, NE Japan, estimated from double-difference hypocenter locations. Earth Planet Sp 55, 741–750 (2003). https://doi.org/10.1186/BF03352483
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1186/BF03352483