摘要
本文基于云南地震台网数据,对2021年6月10日云南双柏地震序列进行重新定位,并对序列中4次M_(S)≥3.5地震的震源机制解和震源区构造应力场进行了反演,研究了双柏地震序列时空分布特征和发震构造.地震重定位结果显示,双柏地震序列空间上呈NNE-SSW向优势分布,发震断层较为陡立,震源深度集中分布于5~15 km范围内,震源深度表现为南浅北深的特征.M_(S)5.1地震后余震序列在时空上呈现出不对称的双侧发展模式,M_(S)4.6地震前后余震沿SSW向存在往返迁移现象.反演得到的序列震源机制解类型均为走滑型,都具有与序列优势分布一致的NNE走向、高倾角SEE倾向节面.构造应力场反演表明震源区受到NNW向水平挤压和NEE向水平拉张的构造应力作用.结合重定位结果和序列震源机制分析认为,双柏地震序列与附近的楚雄—建水断裂等无关,其发震构造为一条NNE走向、SEE倾向的高倾角左旋走滑断裂,构造形成受控于川滇菱形块体SSE向整体运动产生的NNW向挤压构造应力作用.
Based on the data of the Yunnan seismic network,we relocated the Shuangbai earthquake sequence in Yunnan on June 10,2021.The focal mechanism solutions of earthquakes with M_(S)≥3.5 and regional tectonic stress field were inverted,and then temporal and spatial distribution characteristics and seismogenic structure of the Shuangbai earthquake sequence were analyzed in the paper.The relocations show that the Shuangbai earthquake sequence was predominantly distributed in the NNE-SSW direction,which the dip angle of seismogenic fault is steep.The dominant depth of the earthquake sequence was between 5 km and 15 km,and the focal depth of earthquake along the NNE direction was gradually shallower from north to south.The aftershock sequence appeared to be an asymmetrical bilateral rupture in spartial-temporal evolution after the M_(S)5.1 earthquake.And there was a phenomenon of round-trip migration along the SSW direction of aftershocks before and after the M_(S)4.6 earthquake.The focal mechanism solutions of earthquake sequence were of strike-slip faulting,which have NNE-striking steep nodal planes consistent with the dominant distribution of earthquake sequence.The stress field inversion revealed that the focal area is affected by the NNW-tending horizontal compression and NEE-tending horizontal tension.By combining the results of relocation and focal mechanism solutions,we deduced that the Shuangbai earthquake sequence has nothing to do with the nearby Chuxiong-Jianshui fault.The seismogenic fault is a left-lateral strike-slip fault with NNE-trending fault dipping SEE.The formation of the structure is controlled by the NNW compressive tectonic stress generated by the SSE overall movement of the Sichuan—Yunnan rhombic block.
作者
樊文杰
左可桢
赵翠萍
王光明
FAN WenJie;ZUO KeZhen;ZHAO CuiPing;WANG GuangMing(Yunnan Earthquake Agency,Kunming 650224,China;Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2023年第5期1991-2006,共16页
Chinese Journal of Geophysics
基金
应急管理部国家自然灾害防治研究院基本科研业务专项(ZDJ2019-21)
地震预测开放基金项目(2021EF0F10)共同资助。
关键词
双柏地震序列
重定位
震源机制
构造应力场
发震构造
Shuangbai earthquake sequence
Relocation
Focal mechanism solution
Tectonic stress field
Seismogenic structure
