深部地质洞穴塌缩的地震学证据——川东褶皱区深部的逆冲兼塌缩型地震的震源机制求解  

Seismological evidence for collapse of a deep geological cave--Focal mechanism of a thrust and collapse earthquake in a deep fold in the east Sichuan area

作　　者：薛霆虓 王亮[2,3] Xue Tingxiao;Wang Liang(School of Civil Engineering,Anhui Jianzhu University,Hefei 230601,China;School of Artificial Intelligence,Hezhou University,Hezhou 542899,China;College of Earth Sciences,Guilin University of Technology,Guilin 541004,China)

机构地区：[1]安徽建筑大学土木工程学院,合肥230601 [2]贺州学院人工智能学院,贺州542899 [3]桂林理工大学地球科学学院,桂林541004

出　　处：《地球与行星物理论评（中英文）》2024年第4期461-468,共8页Reviews of Geophysics and Planetary Physics

基　　金：安徽建筑大学自然科学基金资助项目(2019QDZ17);贺州学院博士科研启动基金项目(2023BSQD01)。

摘　　要：地下深部有大型洞穴吗?本文通过地震学方法推测地下7 km左右仍存在较大的地质洞穴.本研究中使用了完整矩张量反演方法(波形拟合gCAP方法)分析了2016年12月27日在重庆市荣昌区发生的M_(L)4.7地震,得到其完整震源机制的矩张量解,波形拟合度很高.反演结果显示此次地震较为特殊,震源机制是逆冲兼塌缩型,地震矩心深度在地下7 km深处.根据震源机制的结果,加之此地震位于背斜褶皱附近,本文推断此地震的发生是背斜褶皱部的断层发生逆冲,继而导致了褶皱部的地质空洞稳定被打破,发生了垮塌和塌缩.震源机制的结果显示地震矩张量主要是水平分量,而垂直分量较少,此结果和当地构造应力很吻合.研究结果显示了完整矩张量震源机制反演方法对复杂地震的研究是很有效的手段.此外,本区域页岩气钻井深度很深,而且有水压致裂作业,推测地震可能被注水压力所诱发.Do large caves exist deep underground?Through seismological investigations,we speculate the existence of a large geological cave about 7 km beneath the surface.The complete moment tensor inversion method(gCAP)was used to analyze the M_(L)4.7 earthquake that occurred in Rongchang District,Chongqing,on December 27,2016.The complete moment tensor solution of its focal mechanism was obtained,and the waveform fitting was good.The inversion results showed that this relatively special earthquake had a thrust and collapse type source and that the earthquake centroid depth was 7 km.Based on the focal mechanism results and the fact that the earthquake was located near an anticlinal fold,we infer that this earthquake was attributable to thrusting of a fault in the anti-clinal fold,which simultaneously led to destruction of the stability of the geological cavity in the fold,leading to collapse.The focal mechanism results showed that the seismic moment tensor had mainly a horizontal component with less vertical component,which is consistent with the local tectonic stress.The results indicate that the complete moment tensor of the focal mechanism inversion method is an effective means for studying complex earthquakes.In addition,shale gas drilling in this area is very deep and there are hydraulic fracturing operations,suggesting that earthquakes may be induced by the water injection pressure.

关 键 词：荣昌地震 震源机制解 空洞塌缩 

分 类 号：P315[天文地球—地震学]