Viscous lithospheric structure beneath Sumatra inferred from post-seismic gravity changes detected by GRACE

Satellite gravity data of the regional rheological structure of the lithosphere in the vicinity of Sumatra is used as evidence to enable a better understanding of the regional geodynamic environment.The data is interpreted using the theory of post-seismic viscoelastic relaxation.Coand post-seismic c...

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Bibliographic Details
Published in:Science China. Earth sciences 2011-08, Vol.54 (8), p.1257-1267
Main Authors: Wang, WuXing, Shi, YaoLin, Sun, WenKe, Zhang, Jing
Format: Article
Language:English
Subjects:
Earth and Environmental Science
Earth science
Earth Sciences
Earthquakes
GRACE
Gravity
Lithosphere
Research Paper
Seismic activity
Seismology
地球动力学环境
岩石圈结构
粘性
苏门答腊地震
苏门答腊岛
重力变化
震后
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Summary:Satellite gravity data of the regional rheological structure of the lithosphere in the vicinity of Sumatra is used as evidence to enable a better understanding of the regional geodynamic environment.The data is interpreted using the theory of post-seismic viscoelastic relaxation.Coand post-seismic changes in the gravity field resulting from the 2004 M w 9.3 Sumatra earthquake were calculated from Gravity Recovery and Climate Experiment （GRACE） satellite data.A spatial Gaussian filter,500 km wide,was used in the calculation.The results indicate that there were significant co-seismic jumps in both uplifted and subducted regions.The magnitude of the jump in the subducted zone was ～9 10 8 m/s 2,more significant than the ～2 10 8 m/s 2 jump observed in the uplifted zone.However,a positive gravity change occurred in the uplifted zone very soon after the earthquake.The rheological structure of the lithosphere has a great effect on deformation and its determination is a fundamental part of developing reliable numerical simulations in geodynamics.Based on the temporally-variable gravity field observed by GRACE,the viscous lithospheric structure of the Sumatra area is investigated with a self-gravitating,half space,viscoelastic earth model.The estimated viscosity is of the order of 1.0 10 18 Pa·s and there are differences in the rheological parameters on the two sides of the fault.The factors that affect the viscosity are discussed in connection with the tectonic structure of the Sumatra area.
ISSN:1674-7313
1869-1897
DOI:10.1007/s11430-011-4217-y