三维激光扫描技术与断层面形貌量化分析在基岩区古地震研究中的应用  

Application of 3D Laser Scanning and Quantitative Morphology Analysis Method to Bedrock Fault Surface in Paleo-seismic Research in Bedrock Area

作　　者：邹俊杰[1,2] 何宏林 耿爽[1] 石峰 周永胜[1] 孙稳 Zou Junjie;He Honglin;Geng Shuang;Shi Feng;Zhou Yongsheng;Sun Wen(State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China;Shanxi Taiyuan Continental Rift Dynamics National Observation and Research Station,Taiyuan 030025,China)

机构地区：[1]地震动力学国家重点实验室中国地震局地质研究所,北京100029 [2]山西太原大陆裂谷动力学国家野外科学观测研究站,太原030025

出　　处：《震灾防御技术》2022年第1期56-67,共12页Technology for Earthquake Disaster Prevention

基　　金：重点研发计划子项目(2018YFC1504101);国家自然科学基金(U1939201、41872213);中国地震局地震研究所基本科研业务专项(IGCEA-21-25);山西太原大陆裂谷动力学国家野外科学观测研究站基金(NORSTY2021-04)。

摘　　要：由于对第四纪地层的严重依赖,传统古地震探槽研究方法在基岩区难以发挥作用,导致无法获取基岩区断层的强震活动历史。本研究以山西地堑系的交城断裂为目标断裂,以断裂北段2处基岩断层面为研究对象,通过三维激光扫描技术获取基岩断层面高精度形貌,基于变差函数法结合滑动窗口操作量化断层表面形貌特征,开展在基岩区提取断裂古地震信息的实例研究。结果显示,2处基岩断层面的形貌在高度上具有明显的分段特征,指示了断层面在地震事件作用下的分段出露过程。这种断层面形貌分段特征可以用来识别古地震事件和同震位移量。在思西村基岩断层面上,识别出由老到新的3次古地震事件,同震倾滑位移量依次为2.0 m、1.9 m和2.3 m,在上兰镇基岩断层面上,识别出由老到新的3次古地震事件,同震倾滑位移量依次为1.4 m、2.5 m和2.0 m,指示了交城断裂北、中段具有产生同震位移量大于2 m、震级大于7.5级的破裂型地震的能力。上述研究成果表明,基于三维激光扫描和形貌量化分析方法开展基岩断层面古地震研究,可以准确而高效地识别古地震事件次数和同震位移量,扩展古地震的研究对象,拓宽古地震的研究空间。在未来的研究中,可以适时地开展宇宙成因核素测年以测定断层面的暴露年龄,获得发震年代,给予地震序列年龄框架。Due to the heavy reliance on Quaternary strata,traditional trench research methods are difficult to apply in the bedrock area,resulting in the inability to obtain strong seismic activity history on faults in the bedrock area.In this study,the Jiaocheng Fault in the Shanxi Rift is selected as the target fault,and the two bedrock fault surfaces in the northern segment are taken as the study object to carry out case studies.The variogram combined with the sliding window operation quantifies the morphologic features of the fault sur-face and extracts the paleo-seismic information.The results show that the morphology of the two bedrock fault surfaces has segmenta-tion in height,indicating the exposure process of the fault surfaces under the action of periodic seismic events.Therefore,paleo-earth-quake events and co-seismic slips can be identified by the morphological segments.Accordingly,three paleo-earthquake events were identified on the bedrock fault of Sixi village,and the co-seismic dip slips were 2.0 m,1.9 m and 2.3 m in sequence.The co-seismic dip slips of the three paleoearthquakes are 1.4m,2.5 m and 2.0 m in sequence.The results indicate that the northern segment of the northern and middle segments of Jiaocheng fault can produce ruptures with a co-seismic slip greater than 2 m and a magnitude greater than M7.5.The above results also show that the paleo-seismic research on bedrock fault surfaces based on t-LiDAR and morphological quantitat-ive analysis can accurately and efficiently identify the number of paleo-earthquake and co-seismic slips,increase the objects of paleo-earthquakes,and expand research space of paleo-earthquakes.In future research,cosmogenic nuclide dating can be carried out timely to determine the exposure age of the fault surface,obtain the earthquake ages,and provide an age frame to the earthquake sequences.

关 键 词：基岩断层面 高精度定量形貌 三维激光扫描技术 古地震识别 交城断裂 

分 类 号：P315.7[天文地球—地震学]