利用黏弹性球体位错理论研究2004年苏门答腊地震震后效应对华南块体的影响  

A study of post-seismic effect of the 2004 Sumatra earthquake on the South China Block based on the viscoelastic spherical dislocation theory

作　　者：刘泰 邹镇宇[1] 吴伟伟[1] 佘雅文[1] 付广裕 孟国杰[1] LIU Tai;ZOU ZhenYu;WU WeiWei;SHE YaWen;FU GuangYu;MENG GuoJie(Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China;School of Geophysics and Information Technology,China University of Geosciences,Beijing 100083,China)

机构地区：[1]中国地震局地震预测研究所,北京100036 [2]中国地质大学(北京)地球物理与信息技术学院,北京100083

出　　处：《地球物理学报》2024年第9期3424-3435,共12页Chinese Journal of Geophysics

基　　金：国家自然科学基金(42104086,42274008);中国地震局地震预测研究所基本科研业务费专项(CEAIEF20240208,CEAIEF2024030103,CEAIEF2024030104)联合资助。

摘　　要：本文基于黏弹性球体位错理论和GNSS观测资料,约束东南亚地区大范围地幔黏滞性结构,探讨该地震的震后形变及其对华南块体的影响.首先收集泰国地区震后位移资料,考虑兼顾稳态和瞬态震后形变的Burgers黏弹性体,利用黏弹性球体位错理论进行模拟,得到软流圈麦克斯韦黏滞性系数(η_(m))为5×10^(18)Pa·s,开尔文体黏滞性系数与麦克斯韦体比值(α)为0.3,开尔文体剪切模量与麦克斯韦体比值(γ)为0.33.进而收集和模拟华南块体及其周边区域震后形变,GNSS流动站观测资料显示震后2年形变主要集中于华南块体南部,观测与模拟震后位移方向整体一致,往西南方向指向震中,震后形变量上存在明显差异,云南地区模拟值偏大,而华南块体南部模拟值偏小.GNSS连续站观测资料显示,华南块体受苏门答腊地震震后形变的影响在2010年后明显减弱.后续地壳变形研究以华南块体为参考基准时,建议基于2016年以后的观测提取速度场.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(η_(m))of asthenosphere is 5×10^(18)Pa·s,the ratio of the Kelvin body viscosity coefficient to the Maxwell body viscosity(α)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 

分 类 号：P315[天文地球—地震学]