Abstract: Few large earthquakes(M_S≥7)have ever occurred in the historical records in eastern China,especially in southeast continental region of 105°～120°E,20°～35°N. However,many moderate-strong earthquakes with magnitude between 5 and 6 occurred there,such as the 1962 Heyuan M_S 6.4 earthquake and 1969 Yangjiang M_S 6.7 earthquake in Guangdong province,the 1974 Liyang M_S 6.0 earthquake in Jiangsu province,1979 Guzhen M_S 5.0 earthquake in Anhui province,and the 2005 Jiujiang M_S 5.7 earthquake in Jiangxi province and so on. These earthquakes have no significant earthquake ruptures,and few late Pleistocene active faults were discovered. So,the seismogeological background of the above moderate-strong earthquakes is still unclear up to the present,that is to say, it is very necessary to study the seismogeologic evidence for moderate earthquakes. In the paper,by analysis of the seismogeologic evidence of the 1979 Liyang M_S 6.0 earthquake in Jiangsu province,the 2005 Jiujiang-Ruichang M_S 5.7 earthquake in Jiangxi province,the 1710 Xinhua M_S 5(1/2) earthquake in Hunan province,the 1917 Huoshan M_S 6(1/4) earthquake in Anhui province and the moderate-strong earthquakes around Dongting Lake,some conclusions are obtained as follows: 1)most moderate-strong earthquakes in east China occurred at regions near the early Quaternary active faults,and regions with early-middle Pleistocene active faults; 2)most moderate-strong earthquakes in East China are related to the development and distribution of the Quaternary down-faulted basins. 3)moderate-strong earthquakes in East China may occur at regions with evident active tectonic geomorphological characteristics in Quaternary,such as the areas with linear fault geomorphology or geomorphologic surface; 4)moderate-strong earthquakes may occur in the seismic gaps along the seismic zones where earthquakes with magnitudes 4～5 occurred in the history.

Key words: seismogeologic evidence, moderate-strong earthquakes, East China

摘要： 中国东部地区,尤其是105°～120°E,20°～35°N的中国东南部大陆地区,自有史记载以来,少有7级以上的地震发生,却有不少5～6级左右的中强地震。研究此类中强地震发生的地震地质标志很有必要。对此,经初步分析认为:1)中国东部大多数中强地震发生在早第四纪(早、中更新世)活动断裂带附近;2)中国东部大多数5～6级中强地震都与第四纪断陷盆地的发育、分布有关;3)具有明显第四纪活动的构造地貌特征的地区,如线性断层地貌或地貌面的线性分布区具备孕发中强地震的可能性;4)有历史记载以来4～5级地震活动带的空区或缺震地区,也存在发育5～6级地震的可能性。

关键词: 地震地质标志, 中强地震, 中国东部