Seismic tomography and anisotropy in the source area of the 2008 Iwate-Miyagi earthquake (M 7.2)

Bin Cheng, Dapeng Zhao, Guowei Zhang

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)

Abstract

In order to understand the generation mechanism of the Iwate-Miyagi earthquake (M 7.2) that occurred on 14 June 2008 in Northeast Japan, we determined high-resolution 3D seismic velocity (Vp, Vs) and Poisson's ratio (σ) structures as well as P-wave azimuthal anisotropy in and around the source area using 246,623 P-wave and 189,153 S-wave high-quality arrival times from 1941 aftershocks of the 2008 Iwate-Miyagi earthquake as well as 4878 shallow and intermediate-depth earthquakes in this area recorded by the dense High-Sensitivity Seismic Network (Hi-net) and the seismic stations of Tohoku University. Our results show that hypocenters of the mainshock and three large aftershocks are located in a boundary zone where both seismic velocity and Poisson's ratio change drastically in a short distance. A zone with pronounced low-velocity and high Poisson's ratio is revealed in the lower crust and uppermost mantle under the source area, which may reflect the arc magma and fluids ascending from the upper-mantle wedge. The P-wave azimuthal anisotropy is complex under the study area, which may also indicate the complex crustal structure there. These results indicate that the generation of the 2008 Iwate-Miyagi earthquake was influenced by the ascending arc magma and fluids associated with the dehydration reactions of the subducting Pacific slab under Northeast Japan.

Original languageEnglish
Pages (from-to)172-185
Number of pages14
JournalPhysics of the Earth and Planetary Interiors
Volume184
Issue number3-4
DOIs
Publication statusPublished - 2011 Feb

Keywords

  • Crustal earthquake
  • Magma and fluids
  • Seismic anisotropy
  • Seismic tomography
  • Slab dehydration
  • The 2008 iwate-Miyagi earthquake

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Geophysics
  • Physics and Astronomy (miscellaneous)
  • Space and Planetary Science

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