利用断层自动剖分技术反演汶川MW7.9地震滑动分布*
毕研磊,张永志,曹海坤,杨九元,杨 珍

(长安大学 地质工程与测绘学院,陕西 西安 710064)

断层自动剖分; 同震滑动分布; 位错元; 地震矩; GPS数据

The Wenchuan MW7.9 Earthquake Slip Distribution Inversion Based on Automated Fault Discretization Method
BI Yanlei,ZHANG Yongzhi,CAO Haikun,YANG Jiuyuan,YANG Zhen

(School of Geology Engineering and Geomatics,Chang'an University,Xi'an 710064,Shaanxi,China)

automated fault discretization; coseismic slip distribution; dislocation element; seismic moment; GPS data

备注

基于GPS数据,利用断层自动剖分技术来反演汶川MW7.9同震滑动分布。反演结果显示:(1)断层自动剖分的滑动分布反演结果在各个位错元之间表现出良好的平滑性。(2)此次地震是一次逆冲型地震,并带有少量的右旋走滑分量。其中映秀―北川断裂滑动最大值为15 m,平均滑动量2.61 m; 灌县―江油断裂滑动的最大值为8 m,平均滑动量为1.58 m。反演得到此次地震的地震矩M0为9.153 8×1020 N·m,矩震级MW为7.91。(3)正演结果与实测数据对比显示,两者位移场在运动趋势上基本保持一致,拟合残差的均方误差在合理范围内,验证了断层自动剖分技术的可行性。

Based on GPS data,we have inversed the Wenchuan MW7.9 coseismic slip distributions by utilizing automated fault model discretization method. The results show:(1)The slip distributions based on automated fault model discretization appear well smooth.(2)It was a thrust-type earthquake with a small amount of right-lateral slip component. In Yingxiu-Beichuan fracture zone,the maximal sliding reached 15 m,average magnitude is 2.61 m. In the Guanxian-Jiangyou fracture zone,the maximal sliding reached 8 m,average sliding magnitude is 1.58 m. Meanwhile the inversed seismic moment M0 is 9.153 8×1020N·m corresponding to moment magnitude MW is 7.91.(3)The comparison between forward modeling results and the measured results shows that the displacement fields are consistent on the trend of movement,the root mean square error(RMSE)within a reasonable range,and this also verifies the feasibility of automated fault model discretization method.