Study On Crustal Deformation Characteristics Of The Southern Segment Of The Honghe Fault Zone Based On SBAS-InSAR Technology

The Honghe fault zone is a large strike-slip fault located in the southeastern margin of the Tibetan Plateau.The tectonic activity has obvious spatial and temporal heterogeneity and segmentation characteristics.The tectonic activity in the northern segment is strong,and the tectonic activities in the middle and southern segments are weak.The reason why the segmental structure is weak has been controversial.The monitoring and analysis of the crustal deformation characteristics in the southern section of the Honghe fault zone is expected to provide a deeper understanding of the crustal deformation characteristics of the area,provide real-time data support for local seismic activities and engineering construction to effectively avoid geological disasters,and also provide early warning for local natural disasters.Provide a reference for prevention and control.This paper uses 19 Sentinel-1A ascending data from 2014 to 2018,based on SBAS-InSAR technology,the LOS-to-Crustal deformation rate of the southern segment of the Honghe fault zone is obtained.The regional deformation characteristics are analyzed,the deformation characteristics of the near-fracture zone are analyzed,and the fracture rate and the blocking depth of the fault zone are calculated based on the two-dimensional dislocation model.Analysis and discussion of seismic characteristics of the section.The main results are as follows:1.From the LOS direction of the Honghe fault zone,the deformation rate is available:The overall performance of the area is eastward(northern disk)moving to the right,and the west side(southern disk)is moving to the left,showing right-handed motion characteristics.The crustal deformation of the two plates is obviously different.The north plate is mainly sedimentation,and its value is-5~-7mm/yr.The south plate is mainly uplifted,its value is 6.25~9.5mm/yr,and the fault zone is two.The relative motion rate difference in the LOS direction is about 11.25 to16.5 mm/yr.In the fault zone,the Jianshui and Shiping areas in the northern part ofthe fault show high settlement areas,and the average sedimentation rate is about-13mm/yr.2.The deformation rate of both sides of the fault zone is analyzed by the five sections.The results show that the west side of the southern section of the Honghe fault zone is parallel to the fracture movement rate of 8.1 mm/yr.The east side parallel to the fracture movement rate of 14.4mm / yr,the difference in velocity on both sides is obvious,the east side movement rate of the fault zone is greater than the west side,indicating that there are large differences in the crustal structure on both sides,which may be related to the inconsistency of lithological components on both sides.From the north to the south of the Honghe fault zone,the relative velocity difference between the two sides of the fault zone becomes smaller,and the rate jump is reduced.There are small bulges between Yuanjiang-Honghe County in the southern section of the Honghe fault zone.The rate is different from that of other sections.This may be due to the interruption of the shear zone near the fault zone in this area,and some rock formations are crowded near the Yuanjiang River.Pressure or outflow,resulting in a difference in rate.3.Based on the two-dimensional dislocation model,the occlusion depth and strike-slip rate of the fault zone are calculated.The strike-slip rates from northwest to southeast are 4.72mm/yr,4.19mm/yr,3.96mm/yr,2.81mm/yr,respectively.The strike-slip rate gradually decreases from the northwest direction to the southeast direction,and the blocking depths are 8.97 km,9.1km,10.23 km,and 12.1km,respectively,which gradually increase the value of the fault zone from northwest to southeast.4.Using the data from the M3.0 earthquake from January 1970 to January 2019,the spatial and temporal distribution characteristics of the earthquake in the southern section of the cash fault zone were analyzed,followed by the internal motion characteristics of the Honghe fault zone and surrounding areas after deducting the overall movement,the results of previous studies and the results of this paper analyze and discuss the reasons for the small earthquakes and small magnitudes in the southern section of the Honghe fault zone.The possible reasons are as follows:(1)The southern part of the Honghe fault zone may be dominated by creep.(2)Theintersection of the southern section of the Honghe fault zone and the Xiaojiang fault zone is obviously affected by the Xiaojiang fault zone.The horizontal movement characteristics of the Xiaojiang fault arc are: clockwise movement on the east side and counterclockwise movement on the west side.According to the above: It may be that the Xiaojiang fault absorbs most of the bulk kinetic energy,which makes the section unfavorable for strain energy accumulation.