Seismogenic Structure Of The Zitong Ms4.9 Earthquake On July 29

A MS4.9 earthquake occurred in the Zitong county,Mianyang city,Sichuan Province at 16:20:14.6 on July 29 th 2014,which is the largest earthquake in Zitong county since records began.The earthquake was clearly felt in Chengdu,Deyang and Nanchong and other regions.The study area belongs to small earthquake activities area,earthquake zone and its adjacent area all belong to the blank region for earthquake studying,so the earthquake seismogenic study of Zitong MS4.9 earthquake on July 29 is a great of significance for protecting against and mitigating earthquake disasters in the study area.Through the inversio n method of nearly far shock wave shape to solve the focal mechanism solution of the main earthquake.The focal mechanism solution includes 320°,83°,175° respectively for the strike,dip,and rake angles on the nodal plane ? and 50°,85°,15° on the nodal plane ?;182°,4°respectively for the azimuth and elevation angles on the P-axis;274°,5°respectively for the azimuth and elevation angles on the T-axis and 80°,85°respectively for the azimuth and elevation angles on the N-axis;It is very close to the focal mecha nism solution of Harvard University given.Then using the double difference location method to relocation the foreshock and aftershock of Zitong MS4.9 earthquake.According to the time distribution characteristics of earthquake sequences,the energy attenuation of earthquake quickly.Spatial distribution characteristics of earthquake sequences combined with focal mechanism of the main earthquake,it can be concluded that the nodal plane?of focal mechanism solutions of main earthquake is the seismogenic tectonic fracture surface of zitong MS4.9 earthquake on July 29;The focal mechanism solution shows that before and after the earthquake,the principal compressive stress axis of focal region is near to NS direction and the advocates stress axis is near to EW direction,consistent with the tectonic stress field of central Sichuan area.the attitude towards of seismogenic fault is in NW direction.the tendency of fault is in NE direction,the steep angle is steep,the seismogenic fault dislocation properties for right-lateral strike-slip fault.It based on the geological interpretation of remote sensing image in the study area to carry out field geological landform survey,there is no remarkab le surface rupture trace or fault zone being found,So the seismogenic tectonic fault of Zitong MS4.9 earthquake is a buried fault.According to nodal plane?angle of focal mechanism solutions of main earthquake and precision positioning of the source depth,it can be roughly calculated that the earthquake fault is passing through the main earthquake SW side is about 2.58 km.Settingup five radon measured sections on the basis of field reconnaissance to verify the inferred fault,there are radon anomalies on the five sections.The radon anomaly curve features indicate that seismogenic fracture tendency to NE,each section of the fault widths of fault are 130 m,175 m,220 m,55 m,120 m in that order;five sections control of the seismogenic fault is about 16.8 km long.Using the geological radar to seismogenic fault is further verified by seismogenic fault in NW-SE distribution,tended to NE,agreed well with the results of radon gas measurement.The breakpoint burial depths of geological radar are shallow,the incision stratigraphic age is the Holocene,all which suggests that the latest activity age of the fault is the Holocene.