Rupture process of the 2011 Tohoku‐oki earthquake and absolute elastic strain release

[1] On 11 March 2011, the Tohoku-oki earthquake in eastern Japan and the devastating tsunami that followed it caused severe damage and numerous deaths. To clarify the rupture process of the earthquake, we inverted teleseismic P-wave data applying a novel formulation that takes into account the uncertainty of Green's function, which has been a major error source in waveform inversion. The estimated seismic moment is 5.7 × 1022 Nm (Mw = 9.1), associated with a fault rupture 440 km long and 180 km wide along the plate interface. The source process is characterized by asymmetric bilateral rupture propagation, but we also found continuous slips up-dip from the hypocenter, which led to a large maximum slip (50 m), long slip duration (90 s), and a large stress drop (20 MPa). The long slip duration, large stress drop, extensional (normal faulting) aftershocks in a previously compressional stress regime, and low-angle normal slips at approximately the depth of the plate interface suggest that the earthquake released roughly all of the accumulated elastic strain on the plate interface owing to exceptional weakening of the fault. The stress accumulated on the plate interface was about 20 MPa near the trench and 0–10 MPa in the down-dip source region.

[1]  S. Uyeda,et al.  Thermal state under the Tohoko arc with consideration of crustal heat generation , 1989 .

[2]  Masayuki Kikuchi,et al.  Inversion of complex body waves , 1982 .

[3]  Richard G. Gordon,et al.  Current plate motions , 1990 .

[4]  J. Nocquet,et al.  Slip distribution of the February 27, 2010 Mw = 8.8 Maule Earthquake, central Chile, from static and high‐rate GPS, InSAR, and broadband teleseismic data , 2010 .

[5]  Masaya Matsuura,et al.  Geodetic data inversion using a Bayesian information criterion for spatial distribution of fault slip , 1992 .

[6]  F. Imamura,et al.  The 869 Jogan tsunami deposit and recurrence interval of large-scale tsunami on the Pacific coast of northeast Japan , 2001 .

[7]  T. Seno.  Determination of the pore fluid pressure ratio at seismogenic megathrusts in subduction zones: Implications for strength of asperities and Andean‐type mountain building , 2009 .

[8]  Gregory C. Beroza,et al.  Shallow Dynamic Overshoot and Energetic Deep Rupture in the 2011 Mw 9.0 Tohoku-Oki Earthquake , 2011, Science.

[9]  Robert J. Geller,et al.  Scaling relations for earthquake source parameters and magnitudes , 1976 .

[10]  H. Kanamori.  Mechanics of Earthquakes , 1994 .

[11]  C. Wibberley,et al.  Earthquake slip weakening and asperities explained by thermal pressurization , 2005, Nature.

[12]  H. Ueno,et al.  Source process of the 2011 off the Pacific coast of Tohoku Earthquake with the combination of teleseismic and strong motion data , 2011 .

[13]  Igor A. Beresnev,et al.  Uncertainties in Finite-Fault Slip Inversions: To What Extent to Believe? (A Critical Review) , 2003 .

[14]  Mitsuhiro Matsu'ura,et al.  The 3‐D tectonic stress fields in and around Japan inverted from centroid moment tensor data of seismic events , 2010 .

[15]  Yuji Yagi,et al.  Introduction of uncertainty of Green's function into waveform inversion for seismic source processes , 2011 .

[16]  H. Kanamori.  Focal mechanism of the Tokachi-Oki earthquake of may 16, 1968: Contortion of the lithosphere at a junction of two trenches , 1971 .

[17]  E. Okal,et al.  Evaluation of Tsunami Risk from Regional Earthquakes at Pisco, Peru , 2006 .

[18]  Akira Hasegawa,et al.  Nearly complete stress drop in the 2011 Mw 9.0 off the Pacific coast of Tohoku Earthquake , 2011 .

[19]  Christopher H. Scholz,et al.  Evidence for a strong San Andreas fault , 2000 .

[20]  M. Ando.  Source mechanisms and tectonic significance of historical earthquakes along the nankai trough, Japan , 1975 .

[21]  Hirotugu Akaike,et al.  Likelihood and the Bayes procedure , 1980 .

[22]  D. L. Anderson,et al.  Theoretical Basis of Some Empirical Relations in Seismology by Hiroo Kanamori And , 1975 .

[23]  A. Hasegawa,et al.  Pre- and post-seismic slow slip on the plate boundary off Sanriku, NE Japan associated with three interplate earthquakes as estimated from small repeating earthquake data , 2004 .

[24]  H. Suito,et al.  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 , 2011 .

[25]  M. Vallée,et al.  Imaging coseismic rupture in far field by slip patches , 2004 .

[26]  R. Sibson.  Implications of fault-valve behaviour for rupture nucleation and recurrence , 1992 .

[27]  Sarah E. Minson,et al.  The 2011 Magnitude 9.0 Tohoku-Oki Earthquake: Mosaicking the Megathrust from Seconds to Centuries , 2011, Science.

[28]  Tomowo Hirasawa,et al.  Temporal change of interplate coupling in northeastern Japan during 1995–2002 estimated from continuous GPS observations , 2004 .

[29]  Chihiro Hashimoto,et al.  Interplate seismogenic zones along the Kuril–Japan trench inferred from GPS data inversion , 2009 .

[30]  K. Satake,et al.  Aperiodic recurrence of geologically recorded tsunamis during the past 5500 years in eastern Hokkaido, Japan , 2009 .

[31]  A. Cisternas,et al.  Assessment of the size of large and great historical earthquakes in Peru , 1990 .

[32]  Narumi Takahashi,et al.  Structural characteristics off Miyagi forearc region, the Japan Trench seismogenic zone, deduced from a wide-angle reflection and refraction study , 2005 .

[33]  J. Nakajima,et al.  Revisiting the three M~7 Miyagi-oki earthquakes in the 1930s: possible seismogenic slip on asperities that were re-ruptured during the 1978 M=7.4 Miyagi-oki earthquake , 2006 .

[34]  M. Zoback,et al.  Evidence for a weak interplate thrust fault along the northern Japan subduction zone and implications for the mechanics of thrust faulting and fluid expulsion , 1993 .