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Inverse Method for Static Stress Drop and Application to the 2011 M w 9.0 Tohoku‐Oki Earthquake
Author(s) -
Xie Zhoumin,
Cai Yongen
Publication year - 2018
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2017jb014871
Subject(s) - aftershock , trench , seismic moment , geology , seismology , slip (aerodynamics) , drop (telecommunication) , moment magnitude scale , shear stress , fault (geology) , geodesy , geometry , mechanics , materials science , physics , mathematics , engineering , composite material , thermodynamics , telecommunications , layer (electronics) , scaling
Seismic stress drop is a fundamental parameter for the investigation of earthquake mechanism. In general, it is indirectly predicted by fault slip based on the dislocation source model or seismic moment; inversion for the stress change on faults has not received the deserved attention. In this study, we propose a finite element method to invert the stress drop on fault, constrained by the observed coseismic deformation. Rupture termination and displacement on fault are automatically predicted from the model. Applying the method to the 2011 M w 9.0 Tohoku‐Oki earthquake, we find that the fault consists of two asperities with maximum shear stress drops of 11.7 and 10.1 MPa, respectively. The predicted maximum horizontal and vertical displacements on the hanging wall at the Japan Trench are 55.2 and 10.8 m, respectively, in good agreement with observation. The predicted total static moments of the mainshock and the M w 7.9 aftershock, 29 min after the mainshock, are 4.48 × 10 22 and 1.46 × 10 21 Nm, corresponding to moment magnitudes of M w 9.0 and M w 8.0, respectively, again in excellent agreement with the observationally determined M w 9.0 and M w 7.9 by the U.S. Geological Survey.