Analysis Of The Temporal And Spatial Structure Of Earthquake Disasters In The Western Region Based On Structural Foundations

Earthquake is a common natural disaster in the western region of China,which poses a serious threat to the personal and property safety of vast residents in the western region.It is particularly important to study the historical law,the prevention and trend judgement of earthquake disasters,which is of great significance to the regional security and natural disaster prevention system construction.Western China is a region where earthquakes occur frequently.There are many fault zones in the area,and the fault zone area is the focus area of earthquake.Western China can be divided into three structural belts,nalely Himalayan active tectonic zone,Sichuan-Yunnan-Qinghai-Tibet seismic tectonic zone and Xinjiang seismic tectonic zone.The distribution of strong earthquakes in the area has zoning characteristics,forming a number of low-level seismic tectonic belts.Earthquake distribution is concentrated in these tectonic belts,and the relationship between the characteristics of tectonic belts and earthquake events can be studied in the future.This paper attempts to analyze the space-time law of earthquake disasters from the perspective of fault zones,using commensurability calculations,butterfly structure diagram,eommensurability structure and so on,to analyze the temporal and spatial characteristics and judge the future trend of earthquake events in Western China.The conclusions showed as follow:(1)The results of spatial-temporal structure analysis and trend judgment of 11 fault zones in three tectonic zones in western China are obtained.In this paper,it is considered that the time symmetry of earthquakes in this region is good,and the randomness probability and confidence level of undeclared future earthquake trend judgment in most regions are more than 50%,which is of high reference value.The next earthquake in most fault zones may occur in the near future,among which longmenshan fault zone,Brahmaputra fault zone,sanjiang fault zone and other fault zones may have strong earthquakes of higher magnitude in the future.(2)In the study of symmetrical earthquake occurrence period,it is found that the earthquake occurrence period of all fault zones in western China has obvious commonness.For example,the 6-7 year seismogenic period is shown on 6 fault zones,namely,yarlung zangbo river fault zone,sanjiang river fault zone,xianshuihe-anninghe-xiaojiang fault zone,haiyuan fault zone,west kunlun northern margin fault zone and north tianshan mountain fault zone.Similarly,the 12?13 year seismogenic period is shown in 3 fault zones.The 22?23 year seismogenic period is shown in 3 fault zones,and the 36?37 year seismogenic period is shown in 4 fault zones.(3)Through the study of the spatial symmetry of earthquakes in the western region,this paper believes that most regions have obvious spatial symmetry.Most epicentral migration has only one axis of symmetry in longitude or latitude,and a few epicentral migration has two or three axes of symmetry.In the migration rule,"left and right alternation,spiral rise" characteristic is obvious.Specifically,some regions show the migration characteristics is the number of earthquakes on both sides of the symmetry axis is same.Some regions show that the distribution of the number of earthquakes on both sides of the axis of symmetry is different,but the development trend is same.(4)According to the research results in this paper,most of the fault zones in the three major structural areas of the western region are seismically prone areas,and some faults have strong earthquakes(Ms?8).The strong compressional arc-fault(zone)system in the Himalayas is characterized by strong tectonic activity,relatively dispersed earthquake location,and relatively large magnitude.The future seismic trend of qinghai-tibet,sichuan-yunnan fault(area)system,except the east kunlun fault,has a high probability of randomness and no undeclared level,and the time symmetry is obvious,which is related to the good periodicity of tectonic activity in this area.The tectonic activities of the west kunlun,tianshan and altai fault(zone)systems are also relatively active,and the earthquake distribution characteristics are obvious along the fault zone.Spatially,future earthquakes may occur along the fault zone.(5)The paper is of reference value for improving the theoretical system of time-space change of earthquakes and enhancing the understanding of the trend of earthquake events,and can provide reference for the establishment of natural disaster prevention system,the implementation of prevention work and earthquake prevention and disaster reduction work in the future.