Study On The Decline Of Towns In Areas Affected By Earthquakes And Secondary Disasters ——A Case Study Of Longmenshan Fault Zone

The phenomenon of urban decline is a part of the urban development process and it has been widely analyzed by domestic and foreign scholars.However,the phenomenon of urban decline caused by the change of geological environment such as earthquake and its secondary disasters still lacks of wide academic attention.Earthquake is one of the most serious natural disasters.It is difficult to predict,sudden,long lasting,destructive,prone to secondary disasters and has long-term impact.This study explores the correlation between the decline of mountainous towns and earthquakes and their secondary disasters,and puts forward the significance of the study on the relationship between the two.From the perspective of environmental geological disasters,this study focuses on the Longmenshan fault zone as a frequent occurrence area of earthquakes and secondary disasters.As far as the Longmenshan fault zone is concerned,a variety of environmental geological disasters and changes in the natural environment have greatly intensified the economic decline of cities and towns in this area.As the research object,Longmenshan fault zone changes due to its geological conditions.The environmental geological disasters,such as earthquake,debris flow and landslide,occur frequently year by year.These factors make the local population move out of the area,the development of industrial economy is limited,and the road infrastructure is damaged,thus leading to the decline of cities and towns.Therefore,as one of the main reasons for the decline of the areas with unstable geological conditions,environmental geological disasters should receive more academic attention.Earthquakes,as instantaneous and destructive environmental geological disasters and a variety of secondary disasters that have caused various losses to the affected areas for a long time,are the most important environmental geological disasters causing the decline of mountainous cities and towns.It is urgent and necessary that the earthquake and its secondary disasters which affect the decline of towns in Longmenshan area receive more academic attention.After fully expounding the phenomenon of urban decline caused by natural environmental factors,the theoretical review and research progress in China and abroad of complex geological and ecological environment in Longmenshan fault zone,this paper first summarizes the general situation of historical earthquakes in Longmenshan fault zone,then analyzes and summarizes the current situation ofWenchuan earthquake and secondary disasters on May 12,Ya'an earthquake on April 20,urban decline after disasters in population,economy,road traffic,infrastructure and other easily seen consequences.Based on the research framework of the decline characterization under the earthquake and its secondary disasters,this study takes Longmenshan fault zone as the research object.First,it uses the method of qualitative analysis and quantitative analysis to select the areas suffering from Wenchuan earthquake in May 12,2008 and Ya'an earthquake in April 20,2013 as the research area,focusing on the population and economy of 8 cities(prefectures)and 23counties(districts,cities).This paper makes a horizontal comparison of 8 city level regions and 23 county level regions from six aspects: population change of affected counties,labor force situation of affected counties,GDP of key cities and prefectures,GDP analysis of affected counties,and economic situation of farmers in affected counties.Then this paper analyzes the economy under night-time lighting image representation and ARIO model by exploring other scholars works.In addition,this paper analyzes the influence of psychological barriers on the population in the earthquake affected areas,so as to better understand the phenomenon of urban decline in Longmenshan fault zone affected by the earthquake and its secondary disasters.Finally,this paper puts forward the measures to deal with the decline from the aspects of population,industrial economy,road traffic and infrastructure.In order to prevent the loss of population after the disaster,it is necessary to enhance the living space of Longmenshan area,improve the ecological environment of the affected mountainous cities and towns,control the impact of the earthquake and its secondary disasters on the industrial economy from many aspects(such as economic loss assessment,insurance system improvement,road and other infrastructure repair response),and ensure from the aspects of road network planning and infrastructure repair that the lifeline before,during and after the disaster is unblocked.This paper also provides certain theoretical reference for the rural planning and in-depth study of urban and rural decline in the areas with frequent environmental geological disasters.