- Open Access
Coseismic slip distribution of the 1946 Nankai earthquake and aseismic slips caused by the earthquake
Earth, Planets and Space volume 53, pages235–241(2001)
Coseismic slip distribution on the fault plane of the 1946 Nankai earthquake (Mw 8.3) was estimated from inversion of tsunami waveforms. The following three improvements from the previous study (Satake, 1993) were made. (1) Larger number of smaller subfaults is used; (2) the subfaults fit better to the slab geometry; and (3) more detailed bathymetry data are used. The inversion result shows that the agreement between observed and synthetic waveforms is greatly improved from the previous study. In the western half of the source region off Shikoku, a large slip of about 6 m occurred near the down-dip end of the locked zone. The slip on the up-dip or shallow part was very small, indicating a weak seismic coupling in that region. In the eastern half of the source region off Kii peninsula, a large slip of about 3 m extended over the entire locked zone. Large slips on the splay faults in the upper plate estimated from geodetic data (Sagiya and Thatcher, 1999) were not required to explain the tsunami waveforms, suggesting that the large slips were aseismic. Two slip distributions on the down-dip end of the plate interface, one from geodetic data and the other from tsunami waveforms, agree well except for slip beneath Cape Muroto in Shikoku. This suggests that aseismic slip also occurred on the plate interface beneath Cape Muroto.
Aida, I., Numerical experiments for the tsunamis generated off the coast of Nankaido district, Bull. Earthq. Res. Inst., Univ. Tokyo, 56, 713–730, 1981 (in Japanese).
Ando, M., Source mechanisms and tectonic significance of historical earthquakes along the Nankai trough, Japan, Tectonophys., 27, 119–140, 1975.
Ando, M., A fault model of the 1946 Nankaido earthquake derived from tsunami data, Phys. Earth Planet. Inter., 28, 320–336, 1982.
Fitch, T. J. and C. H. Scholz, Mechanism underthrusting in southwest Japan: a model of convergent plate interactions, J. Geophys. Res., 76, 7260–7292, 1971.
Heki, K., S. Miyazaki, and H. Tsuji, Silent fault slip following an interplate thrust earthquake at the Japan Trench, Nature, 386, 595–598, 1997.
Hyndman, R. D., K. Wang, and M. Yamano, Thermal constraints on the seismogenic portion of the southwestern Japan subduction thrust, J. Geophys. Res., 100, 15373–15392, 1995.
Ishibashi, K. and K. Satake, Problems on forecasting great earthquakes in the subduction zones around Japan by means of paleoseismology, Zisin, J. Seism. Soc. Japan, 50, supplement, 1–21, 1998 (in Japanese).
Ito, K., Seismic activity and tectonics in southwestern Japan, Zisin, J. Seism. Soc. Japan, 43, 555–569, 1990 (in Japanese).
Kanamori, H., Tectonic implications of the 1944 Tonankai and the 1946 Nankaido earthquakes, Phys. Earth Planet. Inter., 5, 129–139, 1972.
Mizoue, M., M. Nakamura, N. Seto, Y. Ishiketa, and T. Yokota, Three-layered distribution of microearthquakes in relation to focal mechanism variation in the Kii peninsula, southwestern Honshu, Japan, Bull. Earthq. Res. Inst., Univ. Tokyo, 58, 287–310, 1983.
Okada, Y., Surface deformation duetoshear and tensile faultsinahalf-space, Bull. Seismol. Soc. Am., 75, 1135–1154, 1985.
Okano, K., S. Kimura, T. Konomi, and M. Nakamura, The focal distribution of earthquakes in Shikoku and its surrounding regions, Zisin, J. Seism. Soc. Japan, 38, 93–103, 1985 (in Japanese).
Sagiya, T. and W. Thatcher, Coseismic slip resolution along aplate boundary megathrust: The Nankai Trough, southwest Japan, J. Geophys. Res., 104, 1111–1129, 1999.
Satake, K., Depth distribution of coseismic slip along the Nankai Trough, Japan, from joint inversion of geodetic and tsunami data, J. Geophys. Res., 98, 4553–4565, 1993.
Satake, K., Linear and nonlinear computations for the 1992 Nicaragua earthquake tsunami, Pure and Applied Geophysics, 144, 455–470, 1995.
Tichelaar, B. W. and L. J. Ruff, How good are our best model? Jackknifing, bootstrapping, and earthquake depth, EOS, 70, 593, 605–606, 1989.
Yabuki, T. and M. Matsuura, Geodetic data inversion using a Bayesian information criterion for spatial distribution of fault slip, Geophys. J. Int., 109, 363–375, 1992.
Yamazaki, F. and T. Ooida, Configuration of subducted Philippine Sea plate beneath the Chubu district, central Japan, Zisin, J. Seism. Soc. Japan, 38, 193–201, 1985 (in Japanese).
About this article
Cite this article
Tanioka, Y., Satake, K. Coseismic slip distribution of the 1946 Nankai earthquake and aseismic slips caused by the earthquake. Earth Planet Sp 53, 235–241 (2001). https://doi.org/10.1186/BF03352380
- Slip Distribution
- Geodetic Data
- Plate Interface
- Nankai Trough
- Large Slip