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Post-seismic deformation mechanism of the Mw 9.0 Tohoku-Oki earthquake detected by GPS and GRACE observations

Wuxing Wang, Xiaodong Zhang, Ming Liang, & Jing Zhang

Published August 13, 2018, SCEC Contribution #8466, 2018 SCEC Annual Meeting Poster #128 (PDF)

Poster Image: 
Post-seismic deformation characteristics of the Mw 9.0 Tohoku-Oki earthquake are studied by using GPS and GRACE observations. GPS continuous observations show that the regional post-seismic displacements are characterized by exponential function, and the rate of change accords with the attenuation characteristic of the Omori formula. Significant post-seismic gravity changes are detected by GRACE also, which shows that gravity rises on both sides of the seismic rupture. However, the rate of gravity change is faster on the ocean side. Here we combine the theories of afterslip and viscoelastic dislocation to simulate the post-seismic deformations and explore the comprehensive application of GPS and GRACE observations. The results demonstrate the combination of afterslip and viscoelastic relaxation theories can make a reasonable explanation for the post-seismic deformations of the Mw 9.0 Tohoku-Oki. The contribution of afterslip plays a major role in the initial stage, and it gradually weakens one or two years later, while the contribution of viscoelastic relaxation increases with time. The method of combining GPS and GRACE observations to infer regional viscous structure is formed. Firstly, inverse a preliminary regional viscous structure by post-seismic GPS observation, then modify the viscosity of the deepest layer by GRACE observation, and fine tune the viscosity of the shallower layer by synthetically using GPS and GRACE observations. Finally, determine the regional viscous structure. Based on this method, we estimated the mantle viscous structure in the region of the Mw 9.0 Tohoku-Oki earthquake by GPS and GRACE observations.

Key Words
GPS; GRACE; Post-seismic deformation; Afterslip; Viscoelastic relaxation

Wang, W., Zhang, X., Liang, M., & Zhang, J. (2018, 08). Post-seismic deformation mechanism of the Mw 9.0 Tohoku-Oki earthquake detected by GPS and GRACE observations. Poster Presentation at 2018 SCEC Annual Meeting.

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Tectonic Geodesy