The Tectonic Stress Field In Tien Shan Area And Slip Property Of Seismogenic Fault Of The 2017 Jinghe Ms 6.6 Earthquake

Based on the 652 focal mechanism solutions collected around the Tienshan area,this study carried out the inversion of the stress field in the Tienshan area by using MSATSI software.The inversion results of north-west show that the azimuths of the maximum principal compressive stress of the regional stress field present the gradual process of NNW-NS-NNE from west to east,and The position of the maximum principal compressive stress axis in the southeast region are stable to NNE direction,with a small dip angle.And the minimum principal compressive stress axis are mainly in EW direction with a relatively large dip angle.The larger R values of north-west region indicate that the regional stress field is mainly subjected to horizontal extrusion in NS directions.The compressive components in the central part are relatively large,while are relatively small in the southern and eastern parts.Based on the inversion results of the regional tectonic stress field and the geological survey parameters of the seismogenic fault(Kusongmuxieke mountain front fault),the theoretical slip angle of the fault is estimated to be of 132.6° with an error of 22.5°.The results show that the Kusongmuxieke mountain front fault has a thrust and right-lateral strike-slip property,which is consistent with the geological survey.Another way to judge the slip feature of the fault is the focal mechanism of the earthquake that occurred on it.Firstly,we calculated the theoretical slip angles of the focal mechanisms given by different institutions which occurred on the Kusongmuxieke mountain front fault under the local stress field.We found that the theoretical slip angle is little different from that of the actual seismic focal mechanism.Therefore,the correctness of the local stress field is verified.After that we calculated the three-dimensional rotation angle between the above theoretical focal mechanism and the actual seismic focal mechanism.The results show that the two are consistent within a given error range.After that,base on the Jinghe earthquake aftershock data,we inverted the seismogenic fault plane.The results show that the fault has a thrust and right-lateral strike-slip property.Then we calculated the three-dimensional rotation angle with the above theoretical focal mechanism and verify that the above theoretical focal mechanism is a focal mechanism that can reflect the earthquake on the fault.Based on the above results,we believed that the Kusongmuxieke mountain front fault with a thrust and right-lateral strike-slip property is the seismogenic structure of the Jinghe earthquake,and it is the extension of the Kusongmuxieke mountain front fault to the east.From the perspective of geophysics,the slip properties of Kusongmuxieke mountain front fault are confirmed,which provides the foundation for the research on the seismogenic environment,seismicity and geodynamics in the area.