Abstract
We analyzed the far-field co-seismic response of the M W 9.0 Tohoku-Oki earthquake, which occurred on March 11th 2011 at the Japan Trench plate boundary. Our analysis indicates that the far-field co-seismic displacement was very sensitive to the magnitude of this event, and that a significant co-seismic surface displacement from earthquakes in the Japan Trench region can be observed in Eurasia only for events of M W ≥ 8.0. We also analyzed the temporal characteristics of the near-field post-seismic deformation caused by the afterslip and the viscoelastic relaxation following the Japan earthquake. Next, we performed a simulation to analyze the influence of the two post-seismic effects previously mentioned on the far-field post-seismic crustal deformation. The simulation results help explain the post-seismic crustal deformation observed on the Chinese mainland 1.5 years after the event. Fitting results revealed that after the M W 9.0 Tohoku-Oki earthquake, the afterslip decayed exponentially, and may eventually disappear after 4 years. The far-field post-seismic displacement in Eurasia caused by the viscoelastic relaxation following this earthquake will reach the same magnitude as the co-seismic displacement in approximately 10 years. In addition, the co- and post-seismic Coulomb stress on several NE-trending faults in the northeastern and northern regions of the Chinese mainland were significantly enhanced because of the M W 9.0 earthquake, especially on the Yilan-Yitong and the Dunhua-Mishan faults (the northern section of the Tan-Lu fault zone) as well as the Yalujiang and the Fuyu-Zhaodong faults.
Highlights
On March 11th, 2011, the MW 9.0 Tohoku-Oki earthquake ruptured the plate boundary northeast of Japan
What is noteworthy was that the co-seismic response was instantaneous, and the duration of afterslip was not very long, but the contributions of the post-seismic viscoelastic relaxation induced by this significant earthquake will last a long time
The results show that the crustal deformation subsequent to the earthquake follows an exponential decay trend above the epicenter and that the major post-seismic deformation will occur during the first 100 years following the earthquake (Fig. 9a)
Summary
On March 11th, 2011, the MW 9.0 Tohoku-Oki earthquake ruptured the plate boundary northeast of Japan. We show that the co-seismic displacement exponentially decayed with distance from the epicenter (Fig. 2a) This exponential decay of the co-seismic displacements was observed in both the near-field measurements (collected within the Japanese islands) and the far-field data recorded in eastern China and on the Korean peninsula. Both the moment magnitude and the maximum dislocation were relatively small if only the GPSobserved near-field co-seismic displacement data are used as a constraint (DIAO et al 2011) Post-seismic Far-Field Response Following the March 11, 2011 Tohoku-Oki Earthquake
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