海城地震双向构造活动的研究
A STUDY ON THE BIDIRECTIONAL TECTONIC ACTIVITY OF THE HAICHENG EARTHQUAKE
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摘要: 本文利用海城地震的MS>3.5的5个前震和MS>3.0的18个余震资料,根据文献[2]提供的方法,确定了这些地震断层面破裂方向及破裂传播速度。在海城震区平面上展布结果表明,地震断层面破裂方向与北东向和北西向区域断裂构造走向、震后产生的地裂缝分布方位、地震烈度等震线形态相一致。进一步证明海城7.3级地震前后,不仅与大震断层走向一致的北西向断裂有强烈活动,而且北东向构造也有显著活动。说明后者对海城地震的孕育和发生也起了重要作用。因此,海城地震的发生是两组近于共轭构造活动的结果。Abstract: The authors used the information about five foreshocks (Ms>3.5) and eighteen aftershocks (Ms>3.0) of the Haicheng earthquake of February 1975 to determine the fracture directions of these shock faults and fracture speeds according to the method given in reference [2]. It was found that the distribution of the fracture directions in. the Haicheng shock area are basically consistent with the N-E and N-W strikes of local fracture tectonics,with the strikes of surface fissures created by the aftershocks and with the configuration of the macroscopic isoseismic lines. Further,it was also found that not only the N-W fractures consistent with the fault strike of the major shock were strongly active,but also the N-E faults were evidently active before and after Ms 7.3 Haicheng mainshock,and that the faults striking N-E also played an important role in the seismogenic process. Therefore,the occurrence of the Haicheng earthquake seems to be the result of the activity of two nearly conjugate sets of faults.
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[1] 李荣安,海城地震双破裂型震源的讨论,地震科学研究,1982 3; 53——55,
[2] 卓钮如、李文香、龚镇雄,用多普勒效应研究中小地震的破裂面和破裂传播速度,地震学报,4, 14——26, 1982,
[3] 斗卿哗、李荣安,海城7.3级地震宏观前兆时空演化特征与异常机制,地展地质,5, 55——62, 1983,
[4] 章光月、王碧泉、许绍燮、z. J.菲奇,1975年2月4日海城地震GMs 7.3的前震系列,地震学报,5, 1——14, 1983,
[5] 李邦慧、陈运泰、魏富胜、李志勇,不对称双侧破裂过程的研究及在海城地震的应用,地震学报,1, 133——149,1979.
[6] 马瑾、张渤涛、许秀琴、王宝生,断层交汇区附近的变形特点与声发射特点的实验研究,地震学报,5, 195——206,1983[1] 李荣安,海城地震双破裂型震源的讨论,地震科学研究,1982 3; 53——55,
[2] 卓钮如、李文香、龚镇雄,用多普勒效应研究中小地震的破裂面和破裂传播速度,地震学报,4, 14——26, 1982,
[3] 斗卿哗、李荣安,海城7.3级地震宏观前兆时空演化特征与异常机制,地展地质,5, 55——62, 1983,
[4] 章光月、王碧泉、许绍燮、z. J.菲奇,1975年2月4日海城地震GMs 7.3的前震系列,地震学报,5, 1——14, 1983,
[5] 李邦慧、陈运泰、魏富胜、李志勇,不对称双侧破裂过程的研究及在海城地震的应用,地震学报,1, 133——149,1979.
[6] 马瑾、张渤涛、许秀琴、王宝生,断层交汇区附近的变形特点与声发射特点的实验研究,地震学报,5, 195——206,1983
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