地震超剪切破裂传播过程反演分析  

Inversion Analysis of Seismic Super-shear Rupture Propagation Process

作　　者：刘凌志 邹旭明 万志文 钟菊芳[1] LIU Ling-zhi;ZOU Xu-ming;WAN Zhi-wen;ZHONG Ju-fang(School of Civil and Architectural Engineering,Nanchang Hangkong University,Nanchang 330063,China)

机构地区：[1]南昌航空大学土木建筑学院,南昌330063

出　　处：《南昌航空大学学报（自然科学版）》2022年第4期49-58,共10页Journal of Nanchang Hangkong University(Natural Sciences)

基　　金：国家自然科学基金(51969019,51468045);水利部公益性行业专项(201401009);南昌航空大学研究生创新专项资金(YC2020-098)。

摘　　要：国内外学者对“5.12”汶川地震的发震构造环境及震源破裂传播方式获得了初步认识,但地震中超剪切破裂现象的产生及其影响仍有待深入研究。本文利用经校正的加速度时程积分得到的测点地表位移和GPS获取的位移数据,得到了102°~106°N、30°~33°E区域的汶川地震水平和垂直向同震位移场,由同震位移反演得到了发震断层的滑动分布形式;同震位移场和断层滑动分布展示了映秀-北川断裂带由具有明显逆冲性质的破裂前段经过高川阶区后发展成具右旋走滑特征的后段。采用有限元软件模拟了汶川地震映秀-北川断裂带由亚剪切破裂转换为超剪切破裂的破裂传播过程和地表位移量,讨论了高川阶区的介质属性对超剪切破裂过程的影响。结果表明,高川阶区中砂岩介质促进了超剪切破裂现象的产生,破裂在越过高川阶区后以超剪切波速在北川地区进行传播,使得地表各质点的振动加速度和位移相较于其他区域要大很多,因而造成了该区域更为严重的震害。Scholars at home and abroad have gained a preliminary understanding of the seismogenic structural environment and source rupture propagation mode of the “5.12” Wenchuan earthquake, but the occurrence and impact of the super-shear rupture phenomenon in the earthquake still need to be studied in depth. In this work, with the surface displacements of the survey points obtained by the corrected acceleration time history integration and the displacement data obtained by GPS, the horizontal and vertical coseismic displacement fields of the Wenchuan earthquake in the area of 102° ~106°N and 30°-33°E are obtained. The slip distribution form of the seismogenic fault is obtained from the coseismic displacement inversion. And the coseismic displacement field and fault slip distribution show that the Yingxiu-Beichuan fault zone has developed from the rupture front section with obvious thrust properties through the Gaochuan region to the rear section with right-lateral strike-slip characteristics. The finite element software was used to simulate the rupture propagation process and surface displacement of the Yingxiu-Beichuan fault zone from sub-shear rupture to super-shear rupture, and the influence of the medium properties in Gaochuan zone on the super-shear rupture process was discussed. The results show that the sandstone medium in the Gaochuan terrace promotes the generation of super-shear fracture. The fracture propagates in Beichuan area at a super-shear wave velocity after passing through the Gaochuan region, which makes the vibration acceleration and displacement of each particle on the surface larger than other areas.Consequently, more serious earthquake damage is aroused in the area.

关 键 词：汶川地震 同震位移场 滑动分布 超剪切破裂 介质属性 

分 类 号：P315[天文地球—地震学]