【作者】 成瑾； 陈培善； 涂毅敏； 刘瑞丰； 白彤霞；

【Author】 Cheng Jin, Chen Peishan, Tu Yimin, Liu Ruifeng and Bai Tongxia(Institute oj Geophysics, China Seisrnologtcal Bureau, Heijing 100081, China}

【机构】 中国地震局地球物理研究所；

【摘要】 1998年1月10日03时(世界协调时),在河北省张北县和尚义县交界地区发生了一次M_s6.2地震,在这次地震之后,又发生了一系列的余震。这些地震的发生。为研究该地区的构造应力场提供了一次良好的机会。利用中国数字化台网(CDSN)的长周期波形资料,研究了主震的震源机制,并利用北京数字化遥测台网的宽频带地震波形资料,研究了该地震序列的一些较大余震的震源机制。所用方法的特点是:①使用了宽频带的较高频资料,将哈佛的CMT解的范围扩大到了近场地震和区域地震;②可以同时确定震源的走向、倾角和滑动角以及震源深度;③对于每个接收路径使用不同的层状地球模型,因此,在反演中少了地球模型误差的影响。将主震的结果与美国哈佛大学的CMT解进行了对比,结果是非常相似的。推测这次主震可能的发震断层面为节面Ⅰ,方位角为180°,倾角为70°,滑动角为110°,是压性的断裂。与华北地区地震震源机制的分区跟踪监测的结果相比,此次地震应是在京西北地区的背景应力场的作用下发生的。但是,从部分余震的结果来看,主压应力的方向比较杂乱。据此,认为主断层发震后,应力场进行局部调整,触发次级的断层活动,形成了如此复杂的震源机制。更多还原

【Abstract】 A damaging earthquake occurred in the intersection area of Zhangbei country and Shangyi country of Hebei province on January 10, 1998. There were a series of aftershocks after the mainshock. These events provide a good chance for researching tectonic stress field in the area. The source mechanism of the mamshock had been carefully studied gby using the long period data of China Digital Seismograph Network (CDSN) and the mechanisms of 4 aftershocks had been researched by using the broadband data of Beijing Digital Seismic Network (BDSN) . The work has the follwing characteristics: (1) high-frequency data from broadband seismic stations can be used, this being an extension of the Harvard CMT approach to near-regional events; (2) strike, dip, rake, hypocentre are simultaneously determined; (3) for each source-receiver path a different (most appropriate) layered earth model can be used, thus reducing the influence of the earth-mldel error on the solution of the inverse problem. Comparing with the CMT solution of Harvard University , their results are similar. It is inferred that the nodal plane I is fault plane and its azimuth is 180? dip is 70? strike is 110? It is a pressure fault. The earthquake occurred under controlling of the regional ambient stress field. But the source mechanisms of the partial aftershocks show that the direction ot pressure axis is very disorder. After the mainshock the adjustment of local stress field triggered activities of faults around mainshock, and it formed the complexity of focal mechanisms.更多还原