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2005年九江地震是“相对弱地震活动区”的一次中强破坏性地震.对该地震发生的新构造环境进行了分析,认为震区处于两大构造单元的边界带,具有发生中强地震的构造背景.野外观察并结合地震现场考察的结果显示,地震可能与瑞昌盆地西北边界发育的一条NE向断裂带有关.从丁家山-郎君山断裂对地貌和第四纪地层的控制、地质剖面、ESR年龄等方面对这一盆地边界断裂的活动性进行了考察与分析,认为该断裂在地表露头上表现为一条中更新世活动断裂.根据断裂活动特征和地震产生的地裂缝、等震线形态、震源机制解节面等的走向和位置,推断丁家山-郎君山断裂是九江5.7级地震的发震构造,而该断裂与较新活动的NW向断裂的交汇部位,则可能是该地震的发震部位.分析表明,此次地震并非一次意外事件,其发震断裂活动特征和隐蔽性在中国东部地区具有典型性.
The Jiujiang earthquake in 2005 was a moderately strong destructive earthquake in the area of relatively weak seismic activity.The new tectonic setting of the earthquake was analyzed and it is believed that the earthquake zone is located in the boundary zone between two tectonic units with strong The tectonic setting of the earthquake.The results of the field observation combined with the field investigation show that the earthquake may be related to a NE-trending fault zone developed on the northwestern boundary of the Ruichang Basin.From the control of geomorphology and Quaternary strata on the Dingjushan-Langjunshan fault, Section, and ESR age, the activity of the boundary fault in this basin is investigated and analyzed, and it is considered that this fault is a mid-Pleistocene active fault in the outcrop of the surface.According to the characteristics of the fault activity and the earth fissure produced by the earthquake, the isochronism Line shape and focal mechanism solution plane, we conclude that the Dingjiashan-Langjunshan fault was the seismogenic structure of the Jiujiang MS 5.7 earthquake, and the intersection of this fault and the NW trending fault activity may be the result of the earthquake The analysis shows that the earthquake is not an unexpected event and the characteristics and concealment of the seismogenic fault activity in the eastern part of China are typical.