Slow Slip Transients Before the 2011 Tohoku-Oki Earthquake
*Earthquake and Volcano Research Center, Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
*Earthquake Research Institute, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
I review a spatiotemporal evolution of slow-slip transients on the plate interface of the subducting Pacific plate that happened in and around the mainshock rupture area prior to the 2011 Tohoku-Oki earthquake. Based on foreshock activity before the mainshock, two sequences of slow-slip transients were identified by earthquake migrations toward the initiation point of the mainshock rupture. These two slow-slip transients were also detected by geodetic measurement. The second sequence of slow-slip transients, which involved large slip rates, may have caused significant stress loading onto the hypocenter of the mainshock and prompted the initiation of unstable dynamic rupture. In addition, decadal slip-behavior on the plate interface revealed by geodetic measurement and small repeating earthquakes show that slow-slip transients occurred in the down-dip and up-dip portions of the mainshock rupture area. These slow-slip transients imply the reduction of coupling between the subducting and overlying plates, that could be interpreted as the late stage of mega-thrust earthquake cycle, although this notion remains conjectural.
-  H. Dragert, K. Wang, and T. S. James, “A silent slip event on the deeper Cascadia subduction interface,” Science, Vol.292, pp. 1525-1528, doi:10.1126/science.1060152, 2001.
-  S. Ide, G. C. Beroza, D. R. Shelly, and T. Uchide, “A scaling law for slow earthquakes,” Nature, Vol.447, pp. 76-79, doi:10.1038/nature05780, 2007.
-  H. Kanamori, “Earthquake physics and real-time seismology,” Nature, Vol.451, pp. 271-273, 2008.
-  K. Obara, “Phenomenology of deep slow earthquake family in southwest Japan: Spatiotemporal characteristics and segmentation,” J. Geophys. Res., Vol.115, B00A25, doi:10.1029/2008JB006048, 2010.
-  Z. Peng and J. Gomberg, “An integrated perspective of the continuum between earthquakes and slow-slip phenomena,” Nat. Geosci., Vol.3, pp. 599-607, doi:10.1038/ngeo940, 2010.
-  K. Heki, S. Miyazaki, and H. Tsuji, “Silent fault slip following an interplate thrust earthquake at the Japan Trench,” Nature, Vol.386, pp. 595-598, 1997.
-  S. Miura, I. Iinuma, S. Yui, N. Uchida, T. Sato, K. Tachibana, and A. Hasegawa, “Co- and post-seismic slip associated with the 2005 Miyagioki earthquake (M7.2) as inferred from GPS data,” Earth Planets Space, Vol.58, pp. 1567-1572, 2006.
-  Y. Ito et al., “Episodic slow slip events in the Japan subduction zone before the 2011 Tohoku-Oki earthquake, Tectonophysics,” Vol.600, pp. 14-26, doi:10.1016/j.tecto.2012.08.022, 2013.
-  T. Igarashi, T. Matsuzawa, and A. Hasegawa, “Repeating earthquakes and interplate aseismic slip in the northeastern Japan subduction zone,” J. Geophys. Res., Vol.108, No.B5, pp. 2249, doi:10.1029/2002JB001920, 2003.
-  N. Uchida, T. Matsuzawa, S. Hirahara, and A. Hasegawa, “Small repeating earthquakes and interplate creep around the 2005 Miyagioki earthquake (M7.2),” Earth Planets Space, Vol.58, pp. 1577-1580, 2006.
-  G. Beroza and S. Ide, “Deep tremors and slow quakes,” Science, Vol.324, pp. 1025-1026, doi:10.1126/science.1171231, 2009.
-  M. Bouchon, H. Karabulut, M. Aktar, S. Özalaybey, J. Schmittbuhl, and M. P. Bouin, “Extended nucleation of the 1999 Mw7.6 Izmit earthquake,” Science, Vol.331, pp. 877-880, doi:10.1126/science.1197341, 2011.
-  A. Kato, K. Obara, T. Igarashi, H. Tsuruoka, S. Nakagawa, and N. Hirata, “Propagation of slow slip leading up to the 2011 Mw 9.0 Tohoku-Oki earthquake,” Science, Vol.335, pp. 705-708, doi:10.1126/science.1215141, 2012.
-  Y. Fujii, K. Satake, S. Sakai, M. Shinohara, and T. Kanazawa, “Tsunami source of the 2011 off the Pacific coast of Tohoku earthquake,” Earth Planets Space, Vol.63, No.7, pp. 815-820, doi:10.5047/eps.2011.06.010, 2011.
-  H. Yue and T. Lay, “Inversion of highrate (1 sps) GPS data for rupture process of the 11 March 2011 Tohoku earthquake (Mw9.1),” Geophys. Res. Lett., Vol.38, L00G09, doi:10.1029/2011GL048700, 2011.
-  T. Iinuma et al., “Coseismic slip distribution of the 2011 off the Pacific coast of Tohoku earthquake (M9.0) refined by means of seafloor geodetic data,” J. Geophys. Res., Vol.117, B07409, doi:10.1029/2012JB009186, 2012.
-  F. Hirose, K. Miyaoka, N. Hayashimoto, T. Yamazaki, and M. Nakamura, “Outline of the 2011 off the Pacific coast of Tohoku earthquake (Mw9.0) – seismicity: Foreshocks, main shock, aftershocks and induced activity,” Earth Planets Space, Vol.63, No.7, pp. 513-518, 2011.
-  R. Ando and K. Imanishi, “Possibility of Mw9.0 main shock triggered by diffusional propagation of after-slip from Mw7.3 foreshock,” Earth Planets Space, Vol.63, No.7, pp. 767-771, 2011.
-  Y. Ohta et al., “Geodetic constraints on afterslip characteristics following the March 9, 2011, Sanriku-oki earthquake, Japan,” Geophys. Res. Lett., Vol.39, L16304, doi:10.1029/2012GL052430, 2012.
-  T. Igarashi, “Spatial changes of interplate coupling inferred from sequences of small repeating earthquakes in Japan,” Geophys. Res. Lett., Vol.37, L20304, doi:10.1029/2010GL044609, 2010.
-  S. Miyazaki, P. Segall, J. Fukuda, and T. Kato, “Space time distribution of afterslip following the 2003 Tokachi-oki earthquake: Implications for variations in fault zone frictional properties,” Geophys. Res. Lett., Vol.31, L06623, doi:10.1029/2003GL019410, 2004.
-  S. Miyazaki, J. J. McGuire, and P. Segall, “Seismic and aseismic fault slip before and during the 2011 Tohoku earthquake,” Earth Planets Space, Vol.63, No.7, pp. 637-642, 2011.
-  M. Ohnaka and L. F. Shen, “Scaling of the shear rupture process from nucleation to dynamic propagation: Implications of geometric irregularity of the rupturing surfaces,” J. Geophys. Res., Vol.104, No.B1, pp. 817-884, 1999.
-  A. M. Rubin and J. P. Ampuero, “Earthquake nucleation on (aging) rate and state faults,” J. Geophys. Res., Vol.110, B11312, doi:10.1029/2005JB003686, 2005.
-  S. Latour, A. Schubnel, S. Nielsen, R. Madariaga, and S. Vinciguerra, “Characterization of nucleation during laboratory earthquakes,” Geophys. Res. Lett., Vol.40, pp. 5064-5069, doi:10.1002/grl.50974, 2013.
-  H. Suito, T. Nishimura, M. Tobita, T. Imakiire, and S. Ozawa, “Interplate fault slip along the Japan Trench before the occurrence of the 2011 off the Pacific coast of Tohoku Earthquake as inferred from GPS data,” Earth Planets Space, Vol.63, pp. 615-619, doi:10.5047/eps.2011.06.053, 2011.
-  S. Ozawa, T. Nishimura, H. Munekane, H. Suito, T. Kobayashi, M. Tobita, and T. Imakiire, “Preceding, coseismic, and postseismic slips of the 2011 Tohoku earthquake, Japan,” J. Geophys. Res., Vol.117, B07404, doi:10.1029/2011JB009120, 2012.
-  K. Z. Nanjo, N. Hirata, K. Obara, and K. Kasahara, “Decadescale decrease in b value prior to the M9-class 2011 Tohoku and 2004 Sumatra quakes,” Geophys. Res. Lett., Vol.39, L20304, doi:10.1029/2012GL052997, 2012.
-  S. Tanaka, “Tidal triggering of earthquakes prior to the 2011 Tohoku-Oki earthquake (Mw9.1),” Geophys. Res. Lett., Vo.39, L00G26, doi:10.1029/2012GL051179, 2012.
-  T. Nagao, Y. Orihara, and M. Kamogawa, “Precursory Phenomena Possibly related to the 2011 M9.0 off the Pacific Coast of Tohoku Earthquake,” J. Disaster Res., Vol.9, No.3, pp. 303-310, 2014 (this issue).
-  N. Uchida and T. Matsuzawa, “Pre- and post-seismic slow slip surrounding the 2011 Tohoku-oki earthquake rupture,” Earth Planet. Sci. Lett., Vol.374, pp. 81-91, 10.1016/j.epsl.2013.05.021, 2013.
-  M. Bouchon, V. Durand, D. Marsan, H Karabulut, and J. Schmittbuhl, “The long precursory phase of most large interplate earthquakes,” Nat. Geosci., Vol.6, pp. 299-302, 2013.
-  T. Chen and N. Lapusta, “Scaling of small repeating earthquakes explained by interaction of seismic and aseismic slip in a rate and state fault model,” J. Geophys. Res., Vol.114, B01311, doi:10.1029/2008JB005749, 2009.
-  T. Hori and S. Miyazaki, “A possible mechanism of M9 earthquake generation cycles in the area of repeating M7-8 earthquakes surrounded by aseismic sliding,” Earth Planets Space, Vol.63, pp. 773-777, doi:10.5047/eps.2011.06.022, 2011.
-  K. Minoura, F. Imamura, D. Sugawara, Y. Kono, and T. Iwashita, “The 869 Jogan tsunami deposit and recurrence interval of largescale tsunami on the Pacific coast of northeast Japan,” J. Nat. Disaster Sci., Vol.23, pp. 83-88, 2001.
-  Y. Sawai, Y. Namegaya, Y. Okamura, K. Satake, and M. Shishikura, “Challenges of anticipating the 2011 Tohoku earthquake and tsunami using coastal geology,” Geophys. Res. Lett., Vol.39, L21309, doi:10.1029/2012GL053692, 2012.
-  K. Obara, “Contribution of Slow Earthquake Study for Assessing the Occurrence Potential of Megathrust Earthquakes,” J. Disaster Res., Vol.9, No.3, pp. 317-329, 2014 (this issue).