关键词: 新构造运动, 潜在震源区划分, 中更新世, 湘东地区

Abstract: Located in the south China fold system,the eastern Hunan area has experienced several tectonic movements,which resulted in wide-spread distribution of folds accompanied by a series of NNE-NE trending faults,and some rift basins were developed along these faults. During the neotectonic movement,the crustal movement was dominated by large-scale and overall slow uplift with weak differential tectonic movement. However,this area has experienced a number of strong earthquakes,which are supposed to be related to the fault activities in the mid-Quaternary. Based on the collection and analyses of previous results of research in this area and its neighborhood,in this study,we carried out field geological and geomorphologic investigation to the southeastern segment of Changde-Yiyang-Changsha Fault,the northeastern segment of the Xiangtan-Shaodong Fault,and the Yongzhou-Hengyang Fault. Comprehensive analysis was made on the activity of these faults during the early Pleistocene epoch based on the two basic principles of "earthquake recurrence" and "structural analogy". Based on the geological,seismic and geophysical data of specific sites,it is concluded that these fault zones not only put up the evidence of mid Pleistocene activities,but have potential risk of moderate earthquakes in the areas around the fault zones. Considering the needs for social and economic development and other factors,the Xiangtan-Xiangxiang,Shaodong,Hengshan-Hengyang,and Yongzhou areas are regarded as new potential source regions.

Key words: neotectonism, delineation of potential seismic sources, mid-Pleistocene, eastern Hunan area