| 2019年四川长宁MS6.0地震的地质构造成因——区域性构造节理贯通、破裂结果 |
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| 关键词:Sichuan basin Changning MS6.0 earthquake Shuanghe great anticline structural joints seismogenic structure |
| 基金项目:国家自然科学基金项目(编号: 41472204);中国地震局地壳应力研究所中央级公益性科研院所基本科研业务专项(编号: ZDJ2019-21);中国地质调查局项目(编号: DD20160268) |
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| The Geological Genesis of the 2019 Changning MS6.0 Earthquake in Sichuan: Connecting and Rupturing of Regional Structural Joints |
| According to field geological survey results and regional geological data, the authors analyzed geological background and Neotectonic characteristics in Changning MS6.0 earthquake area, discussed the seismogenic structure of this earthquake, and built the seismogenic model of this area. Based on regional geological and seismic data, combined with the surface survey results, the authors have found that the neotectonic movement in this area has the characteristics of intermittent overall weak uplift, no obvious Late Quaternary activity along the faults and relatively weak seismic activity. The epicenter of the strong earthquake is located in the west section of Shuanghe anticline, which experienced the double superimposition of the old NE-trending compressive stress field and clockwise rotation stress field. Two sets of NW-trending and one set of NE-trending joints are widely developed in the core and wing of the great anticline, which show regional distribution characteristics and have formed a certain scale of structural fracture zone (weak zone). The seismic records show that the seismic sequence of this strong earthquake presents obvious NW-trending linear stripe, and the focal mechanism solution mainly indicates the result of NEE-NE-trending horizontal compression stress. Combined with the characteristics of the surface structure, it can be further inferred that the source fracture pattern of the Changning earthquake is characterized by the fracture process of thrusting as the main part and left lateral strike slip component along the NW-trending fracture. The comprehensive analysis shows that the 2019 Changning MS6.0 earthquake may be the result of structural strengthening, transfixion and further fracture of regional NW longitudinal joints caused by overpressure environment in Shuanghe anticline superimposed with NE direction paleotectonic stress field and rotation stress field. |
| CHANG Zu-feng,ZHANG Yan-feng,WANG Guang-ming,ZHANG Shi-min,MAO Ze-bin,LIU Chang-wei.2020.The Geological Genesis of the 2019 Changning MS6.0 Earthquake in Sichuan: Connecting and Rupturing of Regional Structural Joints[J].Acta Geoscientica Sinica,41(4):469-480. |
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