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1119年6级地震是东北地区震级较大的地震,目前对其发震构造背景缺乏深入的研究。本文从深部构造背景、浅层构造条件和深浅部构造关系等方面,对1119年地震的发震构造背景作了剖析。研究认为,本次地震的宏观震中位于扶余-前郭一带,地质构造上,该区处于松辽盆地中央凹陷和东南隆起的交接部位;深部构造背景上,该区是莫霍面起伏的拐点,存在北东向基底断裂和北西向深部断裂,前者规模较大,晚新生代有弱活动,是新构造单元分界线,后者则规模小,且已停止活动;从地球物理场特征看,该区重力场和电场呈北东或北北东走向,背景简单,是东西两密集异常值的转换带。这些特征表明,不同新构造单元相交位置可能容易产生能量的积累而成为孕育地震的有利环境。文章最后对东北地震区几次中强地震的发震部位进行了讨论与分析,认为对于中国东部弱地震区,不同新构造单元的结合地区是中强震孕育的有利部位。
The magnitude 6 earthquake in 1119 is an earthquake of great magnitude in northeastern China. At present, the research on its tectonic setting is lacking. This paper analyzes the seismogenic tectonic setting of the 1119 earthquake from the aspects of deep tectonic setting, shallow tectonic conditions and the relationship between the deep and shallow tectonics. The study shows that the macro epicenter of this earthquake is located in the Fuyu-Qianqou area and the geological structure, which is located at the junction of the central depression and the southeast uplift of the Songliao Basin. On the deep tectonic setting, the area is the inflection point of the Moho, There are NE-trending basement faults and NW-trending deep faults. The former is large in size and weak in the late Cenozoic. It is a new tectonic unit boundary line, and the latter is small in scale and has ceased to be active. From the geophysical field characteristics, The gravitational field and electric field in the area are northeast or north-north-east direction with a simple background and are the conversion belts of the two east-west intensive outliers. These features show that the intersection of different new tectonic units may easily generate energy accumulation and become an advantageous environment for earthquake. In the end, the seismogenic positions of several moderate-strong earthquakes in the northeastern earthquake area are discussed and analyzed. It is concluded that the combination of different new tectonic units is a favorable site for moderate-strong earthquakes in weak earthquake areas in eastern China.