Special Issue: Special Section for the 2004 off the Kii peninsula earthquakes (1)
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Tsunami source of the 2004 off the Kii Peninsula earthquakes inferred from offshore tsunami and coastal tide gauges
Earth, Planets and Space volume 57, pages 173–178 (2005)
Tsunamis from the 2004 off the Kii Peninsula earthquakes (M 7.1 and 7.4) were recorded on offshore tsunami gauges, a GPS tsunami gauge and eight bottom-pressure gauges, as well as coastal tide gauges located south of Honshu and Shikoku. The maximum amplitudes on the GPS and bottom-pressure gauges were several to ten cm, while those on tide gauges were up to 0.9 m. We first computed tsunami waveforms from the earthquake source models proposed Yamanaka (2004) and Yagi (2004) from seismic waveform analysis, and compared them with the observed waveforms. For the first event (foreshock), both models produce similar waveforms with the observations. For the second event (mainshock), the waveforms computed from the Yamanaka model is closer to the observed waveforms, but there are still discrepancies between the observed and computed waveforms. We then performed tsunami waveform inversions to estimate the water height distributions in the source area. The foreshock source is ≈1600 km2 with the maximum water height of 0.2 m. The estimated tsunami source area for the mainshock, ≈3600 km2 with the maximum of 0.6 m, extends ≈60 km toward northwest and ≈40 km southwest from the epicenter along the aftershock distribution, suggesting that multiple faulting was involved in the mainshock.
Aida, I. Numerical estimation of a tsunami source, Zisin (J. Seism. Soc. Jpn) ser 2, 25, 343–352, 1972.
Baba, T., P. R. Cummins, and T. Hori, Compound fault rupture during the 2004 off the Kii Peninsula earthquake (M 7.4) inferred from highly resolved coseismic sea-surface deformation, Earth Planets Space, 57, this issue, 167–172, 2005.
Eguchi, T., Y. Fujinawa, E. Fujita, S. I. Iwasaki, I. Watabe, and H. Fujiwara, A real-time observation network of ocean-bottom-seismometers deployed at the Sagami trough subduction zone, central Japan, Marine Geophys. Res., 20, 73–94, 1998.
Hara, T., Change of the source mechanism of the main shock of the 2004 off the Kii peninsula earthquakes inferred from long period body wave data, Earth Planets Space, 57, this issue, 179–183, 2005.
Iwasaki, S. I., T. Eguchi, Y. Fujinawa, E. Fujita, I. Watabe, E. Fukuyama, H. Fujiwara, and K. Hishiki, Precise tsunami observation system in the deep ocean by an ocean bottom cable network for the prediction of earthquakes and tsunamis, in Perspectives on Tsunami Hazard Reduction, edited by G. Hebenstreit, 47–66, Kluwer Academic Pub., 1997.
Kato, T., Y. Terada, M. Kinoshita, H. Kakimoto, H. Isshiki, M. Matsuishi, A. Yokoyama, and T. Tanno, Real-time observation tsunami by RTK-GPS, Earth Planets Space, 52, 841–845, 2000.
Matsumoto, H. and H. Mikada, Fault geometry of the 2004 off the Kii peninsula earthquake inferred from offshore pressure waveforms, Earth Planets Space, 57, this issue, 161–166, 2005.
Monma, H., N. Fujiwara, R. Iwase, K. Kawaguchi, S. Suzuki, and H. Kinoshita, Monitoring system for submarine earthquakes and deep sea environment, Proc. MTS/IEEE OCEANS ’97, 2, 1453–1459, 1997.
Okada, Y., Surface deformation de to shear and tensile faults in a half-space, Bull. Seism. Soc. Am., 75, 1135–1154, 1985.
Satake, K., Inversion of tsunami waveforms for the estimation of a fault heterogeneity: method and numerical experiments, J. Phys. Earth, 35, 241–254, 1987.
Satake, K., Tsunamis, in International Handbook of Earthquake and Engineering Seismology, 81A, edited by W. H. K. Lee, H. Kanamori, P. C. Jennings, and C. Kisslinger, 437–451, 2002.
Shearer, P. M., Introduction to seismology, Cambridge Univ. Press, 260 pp.
Tichelaar, B. W. and L. J. Ruff, How good are our best models? Jackknifing, Bootstrapping, and earthquake depth, Eos Trans. AGU, 70, 593 and 605–606, 1989.
Yagi, Y., Source model of the Off Kii-Peninsula earthquake, http://iisee.kenken.go.jp/staff/yagi/eq/Japan20040905/Japan200409051.html, 2004.
Yamanaka, Y., Source process of the 2004 Off Kii-Peninsula earthquakes determined from teleseismic body waves, http://www.eri.u-tokyo.ac.jp/sanchu/SeismoNote/2004/EIC153.html, 2004.
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Satake, K., Baba, T., Hirata, K. et al. Tsunami source of the 2004 off the Kii Peninsula earthquakes inferred from offshore tsunami and coastal tide gauges. Earth Planet Sp 57, 173–178 (2005). https://doi.org/10.1186/BF03351811
- Slip Distribution
- Tsunami Source
- Water Height
- Aftershock Distribution
- Tsunami Waveform