메뉴 건너뛰기




Volumn 274, Issue 5294, 1996, Pages 1891-1894

Tomography of the source area of the 1995 Kobe earthquake: Evidence for fluids at the hypocenter?

Author keywords

[No Author keywords available]

Indexed keywords

ARTICLE; EARTHQUAKE; JAPAN; PRIORITY JOURNAL; TOMOGRAPHY;

EID: 0030429595     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.274.5294.1891     Document Type: Article
Times cited : (365)

References (47)
  • 2
    • 84980310830 scopus 로고
    • H. Kanamori, Seismol. Res. Lett. 66, 6 (1995); P. Somerville, Eos 76, 49 (1995).
    • (1995) Eos , vol.76 , pp. 49
    • Somerville, P.1
  • 3
    • 12644259457 scopus 로고
    • Kashima Press, Tokyo
    • T. Hagiwara, Ed., Earthquakes in the Japan Islands: Seismotectonics and Structure (Kashima Press, Tokyo, 1990). The Kobe epicenter is about 200 km north of the Nankai Trough (the major plate boundary between the Philippine Sea plate and the Eurasian plate, Fig. 1C), and about 40 km from the Median Tectonic Line, which is a large strike-slip fault zone in southwestern Japan. Numerous active Quaternary faults exist in the region. In the past century, four major intraplate earthquakes have occurred in central to western Japan: the 1891 Nobi (M = 8), 1927 Tango (M = 7.3), 1943 Tottori (M = 7.2), and 1948 Fukui (M = 7.1) earthquakes. Two historical earthquakes occurred in the vicinity of the Kobe earthquake, M > 7 in 868, and M > 6 in 1916.
    • (1990) Earthquakes in the Japan Islands: Seismotectonics and Structure
    • Hagiwara, T.1
  • 4
    • 0000104613 scopus 로고
    • S. Tsuboi et al., J. Seismol. Soc. Japan 42, 277 (1989). More than 90 permanent seismic stations are operated in southwestern Japan by Kyoto University, Nagoya University, Kochi University, Kyushu University, and the University of Tokyo, which are used to detect and record micro-earthquakes in this region. Among the 37 stations used in this study (Fig. 1 B), 33 are equipped with three-component seismographs and four with one-component seismometers. All the P- and S-wave arrival times were double-checked by the analysts of the permanent networks.
    • (1989) J. Seismol. Soc. Japan , vol.42 , pp. 277
    • Tsuboi, S.1
  • 5
    • 12644304848 scopus 로고
    • S. Ohmi, Progr. Abstr. Fall Meet. Seismol. Soc. Japan, A39 (1995); Y. Umeda, Proc. 1996 Japan Earth Planet. Sci. Meet., 36 (1996); N. Hirata and the Urgent Observation Group (GROUP-95) for the 1995 Hyogo-Ken Nanbu Earthquake, J. Phys. Earth, in press. All 30 portable stations are equipped with three-component seismometers. All the P- and S-wave arrival times were double-checked by the GROUP-95 analysts and the present authors. More than 98% of the P- and S-wave data used in this study was generated by the Kobe aftershocks and local micro-earthquakes with M < 3. The dominant frequency was 8 to 10 Hz for P waves and 5 to 8 Hz for S waves, and the Fresnel zones did not exceed 0.8 km, which is much smaller than the grid spacing we adopted in this study.
    • (1995) Progr. Abstr. Fall Meet. Seismol. Soc. Japan
    • Ohmi, S.1
  • 6
    • 12644293775 scopus 로고    scopus 로고
    • S. Ohmi, Progr. Abstr. Fall Meet. Seismol. Soc. Japan, A39 (1995); Y. Umeda, Proc. 1996 Japan Earth Planet. Sci. Meet., 36 (1996); N. Hirata and the Urgent Observation Group (GROUP-95) for the 1995 Hyogo-Ken Nanbu Earthquake, J. Phys. Earth, in press. All 30 portable stations are equipped with three-component seismometers. All the P- and S-wave arrival times were double-checked by the GROUP-95 analysts and the present authors. More than 98% of the P- and S-wave data used in this study was generated by the Kobe aftershocks and local micro-earthquakes with M < 3. The dominant frequency was 8 to 10 Hz for P waves and 5 to 8 Hz for S waves, and the Fresnel zones did not exceed 0.8 km, which is much smaller than the grid spacing we adopted in this study.
    • (1996) Proc. 1996 Japan Earth Planet. Sci. Meet. , pp. 36
    • Umeda, Y.1
  • 7
    • 12644312155 scopus 로고    scopus 로고
    • in press
    • S. Ohmi, Progr. Abstr. Fall Meet. Seismol. Soc. Japan, A39 (1995); Y. Umeda, Proc. 1996 Japan Earth Planet. Sci. Meet., 36 (1996); N. Hirata and the Urgent Observation Group (GROUP-95) for the 1995 Hyogo-Ken Nanbu Earthquake, J. Phys. Earth, in press. All 30 portable stations are equipped with three-component seismometers. All the P- and S-wave arrival times were double-checked by the GROUP-95 analysts and the present authors. More than 98% of the P- and S-wave data used in this study was generated by the Kobe aftershocks and local micro-earthquakes with M < 3. The dominant frequency was 8 to 10 Hz for P waves and 5 to 8 Hz for S waves, and the Fresnel zones did not exceed 0.8 km, which is much smaller than the grid spacing we adopted in this study.
    • J. Phys. Earth
    • Hirata, N.1
  • 8
    • 0025627950 scopus 로고
    • J. M. Lees, Geophys. Res. Lett. 17, 1433 (1990); J. M. Lees and C. E. Nicholson, Geology 21, 387 (1993); W. Foxall, A. Michelini, T. V. McEvilly, J. Geophys. Res. 98, 17691 (1993); D. Zhao and H. Kanamori, Geophys. Res. Lett. 20, 1083 (1993); ibid 22, 763 (1995).
    • (1990) Geophys. Res. Lett. , vol.17 , pp. 1433
    • Lees, J.M.1
  • 9
    • 84879890890 scopus 로고
    • J. M. Lees, Geophys. Res. Lett. 17, 1433 (1990); J. M. Lees and C. E. Nicholson, Geology 21, 387 (1993); W. Foxall, A. Michelini, T. V. McEvilly, J. Geophys. Res. 98, 17691 (1993); D. Zhao and H. Kanamori, Geophys. Res. Lett. 20, 1083 (1993); ibid 22, 763 (1995).
    • (1993) Geology , vol.21 , pp. 387
    • Lees, J.M.1    Nicholson, C.E.2
  • 10
    • 12644289254 scopus 로고
    • J. M. Lees, Geophys. Res. Lett. 17, 1433 (1990); J. M. Lees and C. E. Nicholson, Geology 21, 387 (1993); W. Foxall, A. Michelini, T. V. McEvilly, J. Geophys. Res. 98, 17691 (1993); D. Zhao and H. Kanamori, Geophys. Res. Lett. 20, 1083 (1993); ibid 22, 763 (1995).
    • (1993) J. Geophys. Res. , vol.98 , pp. 17691
    • Foxall, W.1    Michelini, A.2    McEvilly, T.V.3
  • 11
    • 0027386346 scopus 로고
    • J. M. Lees, Geophys. Res. Lett. 17, 1433 (1990); J. M. Lees and C. E. Nicholson, Geology 21, 387 (1993); W. Foxall, A. Michelini, T. V. McEvilly, J. Geophys. Res. 98, 17691 (1993); D. Zhao and H. Kanamori, Geophys. Res. Lett. 20, 1083 (1993); ibid 22, 763 (1995).
    • (1993) Geophys. Res. Lett. , vol.20 , pp. 1083
    • Zhao, D.1    Kanamori, H.2
  • 12
    • 0029510767 scopus 로고
    • J. M. Lees, Geophys. Res. Lett. 17, 1433 (1990); J. M. Lees and C. E. Nicholson, Geology 21, 387 (1993); W. Foxall, A. Michelini, T. V. McEvilly, J. Geophys. Res. 98, 17691 (1993); D. Zhao and H. Kanamori, Geophys. Res. Lett. 20, 1083 (1993); ibid 22, 763 (1995).
    • (1995) Geophys. Res. Lett. , vol.22 , pp. 763
  • 13
    • 0027801885 scopus 로고
    • D. Eberhart-Phillips and A. J. Michael, J. Geophys. Res. 98, 15737 (1993); P. A. Johnson and T. V. McEvilly, ibid. 100, 12937 (1995); G. S. Fuis et al., Eos 77, 173 (1996).
    • (1993) J. Geophys. Res. , vol.98 , pp. 15737
    • Eberhart-Phillips, D.1    Michael, A.J.2
  • 14
    • 0029486398 scopus 로고
    • D. Eberhart-Phillips and A. J. Michael, J. Geophys. Res. 98, 15737 (1993); P. A. Johnson and T. V. McEvilly, ibid. 100, 12937 (1995); G. S. Fuis et al., Eos 77, 173 (1996).
    • (1995) J. Geophys. Res. , vol.100 , pp. 12937
    • Johnson, P.A.1    McEvilly, T.V.2
  • 15
    • 0344333190 scopus 로고    scopus 로고
    • D. Eberhart-Phillips and A. J. Michael, J. Geophys. Res. 98, 15737 (1993); P. A. Johnson and T. V. McEvilly, ibid. 100, 12937 (1995); G. S. Fuis et al., Eos 77, 173 (1996).
    • (1996) Eos , vol.77 , pp. 173
    • Fuis, G.S.1
  • 16
    • 0030159361 scopus 로고    scopus 로고
    • H. K. Gupta, S. V. S. Sarma, T. Harinarayana, G. Virupakshi, Geophys. Res. Lett. 23, 1569 (1996). Seismologio and magnetotelluric studies revealed a low-velocity, high conductive anomaly near the hypocenter of the 1993 Latur earthquake in India. The anomaly was interpreted as a fluid-filled, fractured rock matrix that may have contributed to the nucleation of the Latur earthquake.
    • (1996) Geophys. Res. Lett. , vol.23 , pp. 1569
    • Gupta, H.K.1    Sarma, S.V.S.2    Harinarayana, T.3    Virupakshi, G.4
  • 17
    • 0027044743 scopus 로고
    • S ratio is 1.73. The Conrad discontinuity is at a depth of 15 to 17 km, and the Moho is at a depth of 34 to 35 km in the Kobe area (D. Zhao. S. Horiuchi, A. Hasegawa, Tectonophysics 212, 289 (1992)). We have taken into account the Conrad and Moho depth changes in the tomographic inversions and found that the velocity changes due to the Conrad and Moho depth variations are less than 0.5% in the tomographic images (Figs. 2 through 4).
    • (1992) J. Geophys. Res. , vol.97 , pp. 19909
    • Zhao, D.1    Hasegawa, A.2    Horiuchi, S.3
  • 19
    • 0023481167 scopus 로고
    • Fault zones are typically less than 1 km wide and composed of highly fractured material, fault gouge, and fluids; see C. H. Scholz, Geology 15, 493 (1987); S. Cox and C. H. Scholz, J. Struct. Geol. 10, 413 (1988); and C. B. Forster and J. P. Evans, Geophys. Res. Lett. 18, 979 (1991). Since the spacing of grid nodes used in our tomographic inversion is 4 to 5 km, the Kobe earthquake fault zone was imaged as a low-velocity zone not narrower than 4 km.
    • (1987) Geology , vol.15 , pp. 493
    • Scholz, C.H.1
  • 20
    • 0023822874 scopus 로고
    • Fault zones are typically less than 1 km wide and composed of highly fractured material, fault gouge, and fluids; see C. H. Scholz, Geology 15, 493 (1987); S. Cox and C. H. Scholz, J. Struct. Geol. 10, 413 (1988); and C. B. Forster and J. P. Evans, Geophys. Res. Lett. 18, 979 (1991). Since the spacing of grid nodes used in our tomographic inversion is 4 to 5 km, the Kobe earthquake fault zone was imaged as a low-velocity zone not narrower than 4 km.
    • (1988) J. Struct. Geol. , vol.10 , pp. 413
    • Cox, S.1    Scholz, C.H.2
  • 21
    • 0026018378 scopus 로고
    • Fault zones are typically less than 1 km wide and composed of highly fractured material, fault gouge, and fluids; see C. H. Scholz, Geology 15, 493 (1987); S. Cox and C. H. Scholz, J. Struct. Geol. 10, 413 (1988); and C. B. Forster and J. P. Evans, Geophys. Res. Lett. 18, 979 (1991). Since the spacing of grid nodes used in our tomographic inversion is 4 to 5 km, the Kobe earthquake fault zone was imaged as a low-velocity zone not narrower than 4 km.
    • (1991) Geophys. Res. Lett. , vol.18 , pp. 979
    • Forster, C.B.1    Evans, J.P.2
  • 24
    • 85082764540 scopus 로고
    • R. J. O'Connell and B. Budiansky, J. Geophys. Res. 79, 5412 (1974); M. N. Toksoz, C. H. Cheng, A. Timur, Geophysics 41, 621 (1976); D. Moos and M. D. Zoback, J. Geophys. Res. 88, 2345 (1983).
    • (1974) J. Geophys. Res. , vol.79 , pp. 5412
    • O'Connell, R.J.1    Budiansky, B.2
  • 25
    • 85082764540 scopus 로고
    • R. J. O'Connell and B. Budiansky, J. Geophys. Res. 79, 5412 (1974); M. N. Toksoz, C. H. Cheng, A. Timur, Geophysics 41, 621 (1976); D. Moos and M. D. Zoback, J. Geophys. Res. 88, 2345 (1983).
    • (1976) Geophysics , vol.41 , pp. 621
    • Toksoz, M.N.1    Cheng, C.H.2    Timur, A.3
  • 26
    • 0020642396 scopus 로고
    • R. J. O'Connell and B. Budiansky, J. Geophys. Res. 79, 5412 (1974); M. N. Toksoz, C. H. Cheng, A. Timur, Geophysics 41, 621 (1976); D. Moos and M. D. Zoback, J. Geophys. Res. 88, 2345 (1983).
    • (1983) J. Geophys. Res. , vol.88 , pp. 2345
    • Moos, D.1    Zoback, M.D.2
  • 27
    • 12644255656 scopus 로고    scopus 로고
    • note
    • To make a checkerboard, we assigned positive and negative velocity anomalies to the 3D grid nodes. Synthetic data are calculated for the check-erboard model. Then we added random errors of 0.05 to 0.15 s to the synthetic data and inverted them with the same algorithm as we did for the observed data. The inverted image of the checker-board suggests where the resolution is good and where it is poor.
  • 29
    • 12644302155 scopus 로고    scopus 로고
    • E. Fukuyama, ibid., p. A87; K. Tadokoro, Y. Umeda, M. Ando, Proc. 1996 Japan Earth Planet. Sci. Meet., 44 (1996). The direction of the fastest S waves is generally oriented east-west in the Nojima fault zone. The time difference between the two splitting S waves is generally 0.1 s and does not exceed 0.15 s. This means that the effect of S-wave splitting on the accuracy of S-wave arrival-time data is not larger than 0.15 s.
    • Progr. Abstr. Fall Meet. Seismol. Soc. Japan
    • Fukuyama, E.1
  • 30
    • 84905416663 scopus 로고    scopus 로고
    • E. Fukuyama, ibid., p. A87; K. Tadokoro, Y. Umeda, M. Ando, Proc. 1996 Japan Earth Planet. Sci. Meet., 44 (1996). The direction of the fastest S waves is generally oriented east-west in the Nojima fault zone. The time difference between the two splitting S waves is generally 0.1 s and does not exceed 0.15 s. This means that the effect of S-wave splitting on the accuracy of S-wave arrival-time data is not larger than 0.15 s.
    • (1996) Proc. 1996 Japan Earth Planet. Sci. Meet. , pp. 44
    • Tadokoro, K.1    Umeda, Y.2    Ando, M.3
  • 36
    • 0022265821 scopus 로고
    • S. N. Chatterjee, A. M. Pitt, H. M. Iyer, J. Volcanol. Geotherm. Res. 26, 213 (1985); M. C. Walck, J. Geophys. Res. 93, 2047 (1988); A. Hasegawa and D. Zhao, in Magmatic Systems, M. P. Ryan, Ed. (Academic Press, San Diego, 1994), pp. 179-195.
    • (1985) J. Volcanol. Geotherm. Res. , vol.26 , pp. 213
    • Chatterjee, S.N.1    Pitt, A.M.2    Iyer, H.M.3
  • 37
    • 0023715285 scopus 로고
    • S. N. Chatterjee, A. M. Pitt, H. M. Iyer, J. Volcanol. Geotherm. Res. 26, 213 (1985); M. C. Walck, J. Geophys. Res. 93, 2047 (1988); A. Hasegawa and D. Zhao, in Magmatic Systems, M. P. Ryan, Ed. (Academic Press, San Diego, 1994), pp. 179-195.
    • (1988) J. Geophys. Res. , vol.93 , pp. 2047
    • Walck, M.C.1
  • 38
    • 77956853760 scopus 로고
    • M. P. Ryan, Ed. Academic Press, San Diego
    • S. N. Chatterjee, A. M. Pitt, H. M. Iyer, J. Volcanol. Geotherm. Res. 26, 213 (1985); M. C. Walck, J. Geophys. Res. 93, 2047 (1988); A. Hasegawa and D. Zhao, in Magmatic Systems, M. P. Ryan, Ed. (Academic Press, San Diego, 1994), pp. 179-195.
    • (1994) Magmatic Systems , pp. 179-195
    • Hasegawa, A.1    Zhao, D.2
  • 42
    • 0019390029 scopus 로고
    • K. Hirahara, Tectonophysics 79, 1 (1981); D. Zhao, A. Hasegawa, H. Kanamori, J. Geophys. Res. 99, 22313 (1994).
    • (1981) Tectonophysics , vol.79 , pp. 1
    • Hirahara, K.1
  • 44
    • 0019368368 scopus 로고
    • D. W. Simpson, P. G. Richards, Eds. American Geophysical Union, Washington, DC
    • R. H. Sibson, in Earthquake Prediction: An International Review, Maurice Ewing Ser., vol. 4, D. W. Simpson, P. G. Richards, Eds. (American Geophysical Union, Washington, DC, 1981), pp. 593-603; R. H. Sibson, Tectonophysics 211, 283 (1992); S. Hickman, R. H. Sibson, R. Bruhn, J. Geophys. Res. 100, 12831 (1995).
    • (1981) Earthquake Prediction: An International Review, Maurice Ewing Ser. , vol.4 , pp. 593-603
    • Sibson, R.H.1
  • 45
    • 0027098529 scopus 로고
    • R. H. Sibson, in Earthquake Prediction: An International Review, Maurice Ewing Ser., vol. 4, D. W. Simpson, P. G. Richards, Eds. (American Geophysical Union, Washington, DC, 1981), pp. 593-603; R. H. Sibson, Tectonophysics 211, 283 (1992); S. Hickman, R. H. Sibson, R. Bruhn, J. Geophys. Res. 100, 12831 (1995).
    • (1992) Tectonophysics , vol.211 , pp. 283
    • Sibson, R.H.1
  • 46
    • 0019368368 scopus 로고
    • R. H. Sibson, in Earthquake Prediction: An International Review, Maurice Ewing Ser., vol. 4, D. W. Simpson, P. G. Richards, Eds. (American Geophysical Union, Washington, DC, 1981), pp. 593-603; R. H. Sibson, Tectonophysics 211, 283 (1992); S. Hickman, R. H. Sibson, R. Bruhn, J. Geophys. Res. 100, 12831 (1995).
    • (1995) J. Geophys. Res. , vol.100 , pp. 12831
    • Hickman, S.1    Sibson, R.H.2    Bruhn, R.3
  • 47
    • 12644313179 scopus 로고    scopus 로고
    • note
    • We are grateful to the members of the Urgent Observation Group for the 1995 Hyogo-Ken Nanbu Earthquake, who operated the portable stations and picked the P- and S-wave arrival times, and to the staff members of the seismic networks of Kyoto University, Nagoya University, Kochi University, Kyushu University, and the University of Tokyo for providing the data recorded by their permanent networks that were used in this study. J. Vidale and an anonymous referee provided thoughtful reviews, which improved the manuscript. This work was partially supported by a grant from the National Science Foundation (EAR-9526810) to D. Zhao. This paper is Contribution 5785, Division of Geological and Planetary Sciences, California Institute of Technology.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.