JDR Vol.4 No.2 pp. 83-93
doi: 10.20965/jdr.2009.p0083


Underground Structural Anomalies and Slow Earthquake Activities Around Seismogenic Megathrust Earthquake Zone as Revealed by Inland Seismic Observations

Kazushige Obara and Katsuhiko Shiomi

National Research Institute for Earth Science and Disaster Prevention, 3-1 Tennodai, Tsukuba, Ibaraki 305-0006, Japan

December 11, 2008
January 24, 2009
April 1, 2009
Nankai Trough, megathrust earthquake, plate boundary, segmentation, slow earthquake
Seismogenic zones of interplate megathrust earthquakes along the Nankai Trough can be subdivided into several segments. At each segment, seismic rupture has occurred at a recurrence interval of about one century. In many cases, some neighboring segments ruptured simultaneously or sequentially after a short interval. One of the factors that controls the properties of such seismic ruptures is the underground structure, including the plate configuration and heterogeneity around the subducting plate (slab) interface. To clarify the mechanism of megathrust earthquakes, detailed surveys and analyses of the underground structures are required. Moreover, the detection of seismic phenomena on the plate interface is important in discussing interplate coupling and interactions between such events and megathrust earthquakes. More and better knowledge of the underground structure around the plate interface has been accumulated by analyses of high-quality data from high-density seismograph networks in inland areas and from joint seismic explorations of the sea and land. Moreover, knowledge regarding a wide variety of newly detected slow earthquakes has contributed toward our understanding of the subducting plate interface. Additional information about underground structures, such as slab segmentations, is expected to provide a better understanding of the occurrence of megathrust earthquakes.
Cite this article as:
K. Obara and K. Shiomi, “Underground Structural Anomalies and Slow Earthquake Activities Around Seismogenic Megathrust Earthquake Zone as Revealed by Inland Seismic Observations,” J. Disaster Res., Vol.4 No.2, pp. 83-93, 2009.
Data files:
  1. [1] M. Ando, “Source mechanism and tectonic significance of historical earthquakes along the Nankai Trough, Japan,” Tectonophysics, 27, pp. 119-140, 1975.
  2. [2] K. Ishibashi and K. Satake, “Problems on forecasting great earthquakes in the subduction zones around Japan by means of paleoseismology,” J. Seismol. Soc. Jpn. Ser. 2, 50 sep., pp. 1-21, 1998 (in Japanese with English abstract).
  3. [3] The Earthquake Research Committee of the Headquarters for Earthquake Research Promotion, “National seismic hazard maps for Japan (2008),” 2008 (in Japanese).
  4. [4] M. Kikuchi, M. Nakamura, and K. Yoshikawa, “Source rupture processes of the 1944 Tonankai earthquake and the 1945 Mikawa earthquake derived from low-gain seismograms,” Earth Planets Space, 55, pp. 159-172, 2003.
  5. [5] T. Murotani, “Source process of the 1946 Nankai earthquake estimated from seismic waveforms and leveling data,” PhD thesis, Univ. of Tokyo, 2007.
  6. [6] T. Baba, Y. Tanioka, P. R. Cummins, and K. Uhira, “The slip distribution of the 1946 Nankai earthquake estimated from tsunami inversion using a new plate model,” Phys. Earth planet. Inter., 132, pp. 59-73, 2002.
  7. [7] T. Baba and P. R. Cummins, “Contiguous rupture areas of two Nankai Trough earthquakes revealed by high-resolution tsunami waveform inversion,” Geophys. Res. Lett., 32, L08305, doi:10.1029/2004GL022320, 2005.
  8. [8] S. Kodaira, N. Takahashi, A. Nakanishi, S. Miura, and Y. Kaneda, “Subducted seamount imaged in the rupture zone of the 1946 Nankaido earthquake,” Science, 289, pp. 104-106, 2000.
  9. [9] S. Kodaira, E. Kurashimo, J. O. Park, N. Takahashi, A. Nakanishi, S. Miura, T. Iwasaki, N. Hirata, K. Ito, and Y. Kaneda, “Structural factors controlling the rupture process of a megathrust earthquake at the Nankai trough seismogenic zone,” Geophys. J. Int., 149, pp. 815-835, 2002.
  10. [10] E. Kurashimo, M. Tokunaga, N. Hirata, T. Iwasaki, S. Kodaira, Y. Kaneda, K. Ito, R. Nishida, S. Kimura, and T. Igawa, “Geometry of the subducting Philippine Sea plate and the crustal and upper mantle structure beneath eastern Shikoku Island revealed by seismic refraction/wide-angle reflection profiling,” J. Seismol. Soc. Jpn. Ser. 2, pp. 489-505, 2002 (in Japanese with English abstract).
  11. [11] S. Kodaira, T. Hori, A. Ito, S. Miura, G. Fujie, J. -O. Park, T. Baba, H. Sakaguchi, and Y. Kaneda, “A cause of rupture segmentation and synchronization in the Nankai trough revealed by seismic imaging and numerical simulation,” J. Geophys. Res., 111, B09301, doi:10.1029/2005JB004030, 2006.
  12. [12] K. Ito, Y. Umeda, H. Sato, I. Hirose, N. Hirata, T. Kawanaka, and T. Ikawa, “Deep seismic surveys in the Kinki district: Shingu-Maizuru line,” Bull. Earthq. Res. Inst. Univ. Tokyo, 81, pp. 239-245, 2006.
  13. [13] F. Yamazaki and T. Oida, “Configuration of subducted Philippine Sea plate beneath the Chubu district, central Japan,” J. Seismol. Soc. Jpn. Ser. 2,, 38, pp. 193-201, 1985 (in Japanese with English abstract).
  14. [14] Y. Okada, K. Kasahara, S. Hori, K. Obara, S. Sekiguchi, H. Fujiwara, and A. Yamamoto, “Recent progress of seismic observation networks in Japan — Hi-net, F-net, K-NET and KiK-net,” Earth Planets Space, 56, xv-xxviii, 2004.
  15. [15] T. Miyoshi and K. Ishibashi, “Geometry of the seismic Philippine Sea slab beneath the region from Ise Bay to western Shikoku, southwest Japan,” J. Seismol. Soc. Jpn. Ser. 2, 57, pp. 139-152, 2004 (in Japanese with English abstract).
  16. [16] C. A. Langston, “Structure under Mount Rainier, Washington, inferred from teleseismic body waves,” J. Geophys. Res., 84, pp. 4749-4762, 1979.
  17. [17] C. J. Ammon, “The isolation of receiver effects from teleseismic P waveforms,” Bull. seism. Soc. Am., 81, pp. 2504-2510, 1991.
  18. [18] M. Yamauchi, K. Hirahara, and T. Shibutani, “High resolution receiver function imaging of the seismic velocity discontinuities in the crust and the uppermost mantle beneath southwest Japan,” Earth Planets Space, 55, pp. 59-64, 2003.
  19. [19] K. Shiomi, H. Sato, K. Obara, and M. Ohtake, “Configuration of subducting Philippine Sea plate beneath southwest Japan revealed from receiver function analysis based on the multivariate autoregressive model,” J. Geophys. Res., 109, B04308, doi:10.1029/2003JB002774, 2004.
  20. [20] K. Shiomi, M. Matsubara, Y. Ito, and K. Obara, “Simple relationship between seismic activity along Philippine Sea slab and geometry of oceanic Moho beneath southwest Japan,” Geophys. J. Int., 173, pp. 1018-1029, doi:10.1111/j.1365-246X.2008.03786.x, 2008.
  21. [21] K. Hirahara, “Three-dimensional seismic structure beneath southwest Japan: subducting Philippine Sea plate,” Tectonophysics, 79, pp. 1-44, 1981.
  22. [22] J. Nakajima and A. Hasegawa, “Subduction of the Philippine Sea plate beneath southwestern Japan: Slab geometry and its relationship to arc magmatism,” J. Geophys. Res., 112, B08306, doi:10.1029/2006JB004770, 2007.
  23. [23] F. Hirose, J. Nakajima, and A. Hasegawa, “Three-dimensional velocity structure in southwestern Japan and configuration of the Philippine Sea slab estimated by double-difference tomography,” J. Seismol. Soc. Jpn. Ser. 2, 60, pp. 1-20, 2007 (in Japanese with English abstract).
  24. [24] K. Shiomi and J. Park, “Structural features of the subducting slab beneath the Kii Peninsula, central Japan: Seismic evidence of slab segmentation, dehydration, and anisotropy,” J. Geophys. Res., 113, B10318, doi:10.1029/2007JB005535, 2008.
  25. [25] S. Hori, H. Inoue, Y. Fukao, and M. Ukawa, “Seismic detection of the untransformed ‘basaltic’ oceanic crust subducting into the mantle,” Geophys. J. R. Astron. Soc., 83, pp. 169-197, 1985.
  26. [26] T. Ohkura, “Structure of the upper part of the Philippine Sea plate estimated by later phases of upper mantle earthquakes in and around Shikoku, Japan,” Tectonophysics, 321, pp. 17-36, 2000.
  27. [27] T. Miyoshi, “Geometry of the subducted Philippine Sea plate beneath southwest Japan inferred from Hypocentral distribution of earthquakes and seismogram interpretation,” PhD thesis, Kobe University, 2007.
  28. [28] T. Seno, D. Zhao, Y. Kobayashi, and M. Nakamura, “Dehydration of serpentinized slab mantle: Seismic evidence from southwest Japan,” Earth Planets Space, 53, pp. 861-871, 2001.
  29. [29] T. Yamashita, T. Danhara, H. Iwano, H. Hoshi, Y. Kawakami, T. Sumii, H. Shinjoe, and Y. Wada, “Correlation of the Muro Pyroclastic Flow Deposit and the adjacent tuffs in northern Kii Peninsula, southwest Japan, and their source: an approach from mode analysis using refractive index of light minerals,” J. Geol. Soc. Japan, 113, pp. 340-352, 2007 (in Japanese with English abstract).
  30. [30] T. Matsumoto, T. Kawabata, J. Matsuda, K. Yamamoto, and K. Mimura, “3He/4 He ratios in well gasses in the Kinki district, SW Japan: Surface appearance of slab-derived fluids in a non-volcanic area in Kii Peninsula,” Earth Planet. Sci. Lett., 216, pp. 221-230, 2003.
  31. [31] J. Nakajima and A. Hasegawa, “Tomographic evidence for the mantle upwelling beneath southwestern Japan and its implications for arc magmatism,” Earth Planet. Sci. Lett., 254, pp. 90-105, 2007.
  32. [32] H. Shinjoe, T. Sumii, Y. Orihashi, Near trench igneous activities in Middle Miocene Southwest Japan Arc: Connection between magmatism and subduction of hot Shikoku Basin,” Monthly Chikyu extra, 43, pp. 31-38, 2003 (in Japanese).
  33. [33] R. D. Hyndman, M. Yamano, and D. A. Oleskevich, “The seismogenic zone of subduction thrust faults,” Island Arc, 6, pp. 244-260, 1997.
  34. [34] Y. Ishihara, “Major existence of very low frequency earthquakes in background seismicity along subduction zone of south-western Japan,” Eos Trans. AGU, 84(46), 2003.
  35. [35] K. Obara and Y. Ito, “Very low frequency earthquake excited by the 2004 off the Kii peninsula earthquake: A dynamic deformation process in the large accretionary prism,” Earth Planets Space, 57, pp. 321-326, 2005.
  36. [36] K. Obara, K. Kasahara, S. Hori, and Y. Okada, “A densely distributed high-sensitivity seismograph network in Japan: Hi-net by National Research Institute for Earth Science and Disaster Prevention,” Rev. Sci. Instrum., 76, 021301, doi:10.1063/1.1854197, 2005.
  37. [37] K. Shiomi, K. Obara, S. Aoi, and K. Kasahara, “Estimation on the azimuth of the Hi-net and KiK-net borehole seismometers,” J. Seismol. Soc. Jpn., Ser. 2, 56, pp. 99-110, 2003 (in Japanese).
  38. [38] Y. Ito and K. Obara, “Dynamic deformation of the accretionary prism excites very low frequency earthquakes,” Geophys. Res. Lett., 33, L02312, doi:10.1029/2005GL024711, 2006a.
  39. [39] J. O. Park, T. Tsuru, S. Kodaira, P. R. Cummins, and Y. Kaneda, “Splay fault branching along the Nankai subduction zone,” Science, 297, pp. 1157-1160, doi:0.1126/science.1074111, 2002.
  40. [40] Y. Asano, K. Obara, and Y. Ito, “Spatiotemporal distribution of very-low frequency earthquakes in Tokachi-oki near the junction of the Kuril and Japan trenches revealed by using array signal processing,” Earth, Planets and Space, 60, pp. 871-875, 2008.
  41. [41] K. Obara, Y. Haryu, Y. Ito, and K. Shiomi, “Low frequency events occurred during the sequence of aftershock activity of the 2003 Tokachi-Oki earthquake; a dynamic process of the tectonic erosion by subducted seamount,” Earth, Planets and Space, 56, pp. 347-351, 2004a.
  42. [42] Y. Ito and K. Obara, “Very low frequency earthquakes within accretionary prisms are very low stress-drop earthquakes,” Geophys. Res. Lett., 33, L09302, doi:10.1029/2006GL025883, 2006b.
  43. [43] K. Obara, “Nonvolcanic deep tremor associated with subduction in southwest Japan, Science,” 296, pp. 1679-1681, 2002.
  44. [44] Y. Ito, K. Obara, K. Shiomi, S. Sekine, and H. Hirose, “Slow earthquakes coincident with episodic tremors and slow slip events,” Science, 315, pp. 503-506, 2007.
  45. [45] K. Obara, H. Hirose, F. Yamamizu, and K. Kasahara, “Episodic slow slip events accompanied by non-volcanic tremors in southwest Japan subduction zone,” Geophys. Res. Lett., 31, L23602, doi:10.1029/2004GL020848, 2004.
  46. [46] D. R. Shelly, G. C. Beroza, S. Ide, and S. Nakamula, “Low-frequency earthquakes in Shikoku, Japan and their relationship to episodic tremor and slip,” Nature, 442, pp. 188-191, 2006.
  47. [47] S. Ide, D. R. Shelly, and G. C. Beroza, “The mechanism of deep low frequency earthquakes: Further evidence that deep non-volcanic tremor is generated by shear slip on the plate interface,” Geophys. Res. Lett., 34, L03308, doi:10.1029/2006GL028890, 2007.
  48. [48] H. Hirose, and K. Obara, “Repeating short- and long-term slow slip events with deep tremor activity around the Bungo channel region, southwest Japan,” Earth Planets Space, 57, pp. 961-972, 2005.
  49. [49] H. Hirose and K. Obara, “Short-term slow slip and correlated tremor episodes in the Tokai region, central Japan,” Geophys. Res. Lett., 33, L17311, doi:10.1029/2006GL026579, 2006.
  50. [50] K. Obara and H. Hirose, “Non-volcanic deep low-frequency tremors accompanying slow slips in the southwest Japan subduction zone,” Tectonophys., 417, pp. 33-51, 2006.
  51. [51] H. Dragert, K. Wang, and T. S. James, “A silent slip event on the deeper Cascadia subduction interface,” Science, 292, pp. 1525-1528, 2001.
  52. [52] G. Rogers and H. Dragert, “Episodic tremor and slip on the Cascadia subduction zone: The chatter of silent slip,” Science, 300, pp. 1942-1943, 2003.
  53. [53] M. Miyazawa, and J. Mori, “Evidence suggesting fluid flow beneath Japan due to periodic seismic triggering from the 2004 Sumatra-Andaman earthquake,” Geophys. Res. Lett., 33, L05303, doi:10.1029/2005GL025087, 2006.
  54. [54] J. L. Rubinstein, J. E. Vidale, J. Gomberg, P. Bodin, K. C. Creager, and S. D. Malone, “Non-volcanic tremor driven by large transient shear stresses,” Nature, 448, pp. 579-582, doi:10.1038/nature06017, 2007.
  55. [55] J. Gomberg, J. L. Rubinstein, Z. Peng, K. C. Creager, J. E. Vidale, and P. Bodin, “Widespread triggering of nonvolcanic tremor in California,” Science, 319, doi: 10.1126/science.1149164, 2008.
  56. [56] J. L. Rubinstein, M. L. Rocca, J. E. Vidale, K. C. Creager, and A. G. Wech, “Tidal modulation of nonvolcanic tremor,” Science, 319, pp. 186-189, doi:10.1126/science.1150558, 2008.
  57. [57] R. Nakata, N. Suda, and H. Tsuruoka, “Non-volcanic tremor resulting from the combined effect of Earth tides and slow slip events,” Nature Geoscience, 1, pp. 676-678, doi: 10.1038/ngeo288, 2008.
  58. [58] E. E. Davis, K. Becker, K. Wang, K. Obara, Y. Ito, and M. Kinoshita, “A discrete episode of seismic and aseismic deformation of the Nankai Trough subduction zone accretionary prism and incoming Philippine Sea plate,” Earth Planet. Sci. Lett., 242, pp. 73-84, 2006.
  59. [59] H. Dragert, K. Wang, and G. Rogers, “Geodetic and seismic signatures of episodic tremor and slip in the northern Cascadia subduction zone.” Earth Planets Space, 56, pp. 1143-1150, 2004.

Creative Commons License  This article is published under a Creative Commons Attribution 4.0 International License.

*This site is desgined based on HTML5 and CSS3 for modern browsers, e.g. Chrome, Firefox, Safari, Edge, Opera.

Last updated on Jul. 12, 2024