The Tectonic System And Genetic Mechanism Research Of Simao Block In Yunnan Province

Yongping Town in Jinggu of Yunnan Province experienced three times of strong earthquakes from October to December in 2014, which were Ms6.6, Ms5.8, Ms5.9respectively.Jinggu county is located in Simao block,which surrounded by Nantinghe fault,Honghe fault and Lancang—Jinghong fault. This article starting with Jinggu strong earthquakes in 2014,further comb active tectonic system in Simao block.By remote sensing, field investigation, estimate the fault activity rate and other methods.preliminarly discuss the active tectonic system in Simao block and its genetic mechanism, the geological structure causes of earthquake swarm activity, the problem of seismic risk in Simao block. Mainly known as follows:1.Most of the strike of active faults in Simao block is NW, but the NW strlke faults are separated by some NE strike fault in Jinggu basin area.The NW faults are right-lateral strike-slip fault.the NE faults are left-lateral strike-slip fault. The phenomenon above shows that the Simao block affected by the horizontal stress is greater than the influence of vertical stress. Therefore, The approximate parallel distribution of NW right-lateral strike-slip faults and some micro blocks constitutes the basic pattern of active tectonic structure in Simao block.As a whole, the Nw strike faults in Simao block have the Characteristics of “North west direction convergence,south east direction spread out”.Some professor called it “Simao rotation active tectonic system in shape of broom”.2.The deformation mechanism of the active tectonic system in Simao block should give priority to with sequence sliding shear mode. And the block counterclockwise rotation mode is complementary role. Both of the deformation mechanisms can adjust the Qinghai-Tibet plateau extrusion material,and reflect the high level of structural system deformation have effects on low level of tectonic system motion. On the other hand, it also reflect the former tectonic features have influence on the later tectonic system.3.The NW strike faults are the main earthquake controlling structure. The Wuliangshan faults, as a very important active fault in Simao block, which are stillhave strong activity in nowadays. Should be given attention in future Improve fault zone along the population density is larger area of seismic fortification measures. The geological causes of Jinggu earthquake swarm activity revealed : The surface active faults phenomenon is not obvious or the size of seismogenic fault is small,But in a larger area of active faults and discontinuous is in further penetration in the process of parts Will be at the scale of the strong earthquake risk. Therefore, In the future seismic geological work,the government Should strengthen the similar tectonic position of strong earthquake risk in the research and prevention.