Based on the viscoelastic spherical dislocation theory and GNSS observation data,this paper constrains the large-scale mantle viscosity structure in Southeast Asia,and explores the post-seismic deformation after the 2004 Sumatra earthquake and its effect on the South China block.First of all,this paper collected the post-seismic displacement data in Thailand,and considering the Burgers viscoelastic body with steady state and transient deformation characteristics,performed simulations based on the viscoelastic spherical dislocation theory.The results shows that the Maxwell viscosity coefficient(ηm)of asthenosphere is 5×1018Pa·s,the ratio of the Kelvin body viscosity coefficient to the Maxwell body viscosity(a)is 0.3,and the ratio of the Kelvin body shear modulus to the Maxwell body shear modulus(γ)is 0.33.Further,this paper collected and simulated the post-seismic deformation data of the South China Block and its surrounding areas.Campaign GNSS observation data indicate that the post-seismic deformation in 2 years after the earthquake mainly occurred in the southern South China Block.The observed and simulated post-seismic displacement directions are generally consistent,pointing from the southwest to the epicenter.There is a significant difference in the magnitude of post-seismic deformation.The simulated value in Yunnan is relatively large,while that in the southern South China Block is relatively small.Continuous GNSS observation data indicate that the effect of the post-seismic deformation after the 2004 Sumatra earthquake on the South China block has been weakened significantly since 2010.The crustal deformation will be further studied based on the data of the South China Block,it is suggested that the velocity field should be extracted according to the observations after 2016.
关键词
2004年苏门答腊地震/黏弹性体/华南块体/GNSS观测资料
Key words
2004 Sumatra earthquake/Viscoelastic body/South China Block/GNSS observation data
维普
万方数据