| On November 25,2019,an earthquake with a magnitude of Ms5.2 hit Jingxi City,Guangxi Province.The earthquake brought great damage to the local economy and people's livelihood,with direct economic losses amounting to 23.93 million yuan.The earthquake occurred in the Youjiang Basin.Modern tectonics are active in this area duo to joint influence fromthe Indo-Chinese block,Sichuan-Yunnan block and the South China block.9 MS ?4? historical earthquakes of recorded within 150 km of the epicenter.However,limited by the local geographic environment,regional seismic geology research is weak,and the seismogenic structure of historical earthquakes is mostly unclear.Carrying out research on the seismogenic structure of the Jingxi earthquake has certain scientific value and practical significance,and can provide a basis for regional earthquake prevention and disaster reduction decision-making and earthquake disaster risk prevention.Given that the epicenter area is located on the border between China and Vietnam,and field geological survey are difficult.Fully collected multi-source data such as earthquake,geology,remote sensing,topography,this paper develop regional geological structure interpretation and seismogenic structure determination,with a whole-to-local thinking.Basising on the collected geological map(1:200,000 in the country\1:1,000,000 in the overseas),Combining with medium and high-resolution remote sensing images and topographic data,a regional geological structure interpretation mark was established.Finally,a total of 53 structural lines was interpreted in the epicenter area(N22.5 °?23.2°,E106.4°?107°),which supplement and perfect the existing structural data to a certain extent.The remote sensing interpretation results show that the NW geological structure is more prominent than the geological structure,and the geological structure more active than the geological structure,which is the similar as the regional neotectonic activity.The temporal and spatial distribution characteristics of historical earthquakes and modern earthquakes within 150 km of the epicenter indicate that the Jingxi-Chongzuo series of faults have strong seismicity.Based on the analysis of the above results,it is believed that the NW geological structure in the epicenter area is more likely to be the seismogenic structure of this earthquake.In order to further finely determine the seismogenic structure of this earthquake,the seismic phase report and digital waveform data of the Jingxi earthquake sequence recorded by the Guangxi Seismic Network were fully utilized.Use the HYPO2000 and HYPODD methods to accurately locate the Jingxi earthquake sequence;use the simulated annealing method to obtain the optimal solution of the fault plane parameters;use the g CAP method to invert the seismic full moment tensor,and then analyze the geophysical parameters of the seismogenic structure of the earthquake sequence feature.The results of geophysical parameters show that the characteristics of the seismogenic fault have the characteristics of NE strike,SE tendency,and reverse fault,and the moment tensor focal mechanism solution contains obviously non-dual couple components.It is inferred that the seismogenic fault structure of this earthquake is complicated.The results of geophysical parameters show that the characteristics of the seismogenic fault have the characteristics of NE strike,SE tendency,and reverse fault,and the moment tensor focal mechanism solution contains obviously non-dual couple components.It is inferred that the seismogenic fault structure of this earthquake is complicated.Based on the results of comprehensive structural investigation,remote sensing interpretation,and geophysical parameters,it is analyzed that the seismic control structure of the 2019 Ms5.2 Jingxi earthquake may be two left-handed strike-slip faults which belong the Jingxi-Chongzuo regional fault.The caused structure is a squeezed Xia Lei-Shang Ying fault in the oblique area of the Jingxi-Chongzuo regional fault. |
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