【摘要】 1998年 1月 10日北京时间 11时 5 0分 (0 3时 5 0分UTC) ,在北京西北约 180km的河北省张北县与尚义县交界地区发生的ML=6 .2地震 .该地震是近年华北地区的重要地震事件 .由于地表未见明显的活动断裂展布 ,震后的野外考察未给出任何优势走向的地表破裂资料 ,余震分布也没有显示出优势的展布方向 ,因此发震构造不清楚 .笔者曾应用主事件相对定位方法 ,对张北—尚义地震序列的主震和ML≥ 3.0余震重新精确定位 ,得出结论 :张北—尚义地震序列的主震震中位置为 4 1.14 5°N、114 .4 6 2°E ,位于宏观震中的北东方向约 4km处 ,震源深度 15km ;余震震源分布在走向 180°～ 2 0 0°、接近于竖直的平面内及其附近 .这一重新精确定位的结果表明 ,张北—尚义地震的发震构造是一北北东向的断层 .文中作者应用另一相对定位方法双差地震定位法 ,对张北—尚义地震序列的主震和ML≥ 3.0余震再度进行精确定位 .双差地震定位法重新定位后 ,得出结论 :张北—尚义地震序列的主震震中位置为 4 1.131°N、114 .4 5 6°E ,位于宏观震中的北东方向约 2 .5km处 ,震源深度 12 .8km ;余震震源也分布在走向N10°E的接近于竖直的平面内及其附近 .这一重新精确定位的结果 ,再次表明张北—尚义地震的发震构造是一北北东向的断层更多还原

【Abstract】 On January 10, 1998, at 11h50min Beijing Time (03h50min UTC), an earthquake of M L=6.2 occurred in the border region between the Zhangbei County and Shangyi County of Hebei Province. This earthquake is the most significant event to have occurred in northern China in the recent years. The earthquake generating structure of this event was not clear due to no active fault capable of generating a moderate earthquake was found in the epicentral area, nor surface ruptures with any predominate orientation were observed, no district orientation of its aftershock distribution given by routine earthquake location was shown. To study the seismogenic structure of the Zhangbei Shangyi earthquake, the main shock and its aftershocks with M L≥3.0 of the Zhangbei Shangyi earthquake sequence were relocated by the authors of this paper in 2002 using the master event relative relocation technique. The relocated epicenter of the main shock was located at 41.145°N, 114.462°E, which was located 4 km to the NE of the macro epicenter of this event. The relocated focal depth of the main shock was 15 km. Hypocenters of the aftershocks distributed in a nearly vertical plane striking 180°～200° and its vicinity. The relocated results of the Zhangbei Shangyi earthquake sequence clearly indicated that the seismogenic structure of this event was a NNE SSW striking fault with right lateral and reverse slip. In this paper, a relocation of the Zhangbei Shangyi earthquake sequence has been done using the double difference earthquake location algorithm (DD algorithm), and consistent results with that obtained by the master event technique were obtained. The relocated hypocenters of the main shock are located at 41.131°N, 114.456°E, which was located 2.5 km to the NE of the macro epicenter of the main shock. The relocated focal depth of the main shock was 12.8 km. Hypocenters of the aftershocks also distributed in a nearly vertical N10°E striking plane and its vicinity. The relocated results using DD algorithm clearly indicated that the seismogenic structure of this event was a NNE striking fault again.更多还原