【摘要】 对由四川台网提供的2008年5月12日至2008年12月31日期间发生的地震观测报告资料进行了整理,并根据研究需要从中挑选出了2957次地震事件用于地震定位研究。然后,采用双差定位方法对汶川M_s8.0级地震及挑选出的余震进行了重新定位,得到2678个地震的震源位置,重新定位后走时均方根残差由重新定位前的1.01s降到了0.20s,水平和垂直方向标准差分别为±0.85km和±1.3km。余震震中沿走向分布的总长度约为350km,震源深度优势分布为5～20km,平均震源深度为11.4km。文章结合地表考察破裂、震源机制解等研究结果,对余震空间分布进行了更为详细的分段和讨论,提出以下3点认识:1)余震震中沿主破裂带表现出明显的空间分段活动特征,根据余震空间分布特征和震源机制解可推测断层运动方式由一开始的逆冲为主,经过渡段最终转换为以右旋走滑为主;2)沿小鱼洞-棉篪-理县和青川-文县方向延伸的北西向余震带存在两个与龙门山构造带走向近似垂直的捩断层;3)龙门山构造带的北段(水观乡以北),存在一个斜跨北川-映秀断裂和青川-平武断裂的隐伏断层,并且该隐伏断层参与了北段余震的发震过程。更多还原

【Abstract】 In this paper,the observation data reports of earthquakes occurred during the period of May 12,2008 to December 31,2008,provided by Sichuan seismic networks,were dealt with and 2957 earthquake events were selected to be used for earthquake location research according to the demand of the research.Then,the Wenchuan M_S8.0 earthquake and its 2957 aftershocks were relocated using the double difference algorithm.As a result,the root-mean-square residual error of the travel time of the selected earthquakes reduced from 1.01s before relocation to 0.20s after relocation and the horizontal and vertical standard errors of 2678 relocated hypocenters are±0.85km and±1.3km,respectively.The total spatial distribution length of aftershock epicenters is about 350km and the predominance distribution of focal depth is 5～20km,with the average depth of 11.4km.Finally,three conclusions as follows can be obtained :(1)the epicenters of aftershocks exhibit obvious spatial segmentation characteristic along main rupture zones,but according to the focal depth distribution of aftershocks and the focal mechanism solutions,it can be inferred that the fault movement be dominated by thrust at the beginning and then turned into right-lateral strike-slip;(2)there probably are two north-west tear faults which extend along Xiaoyudong-Mianchi-Lixian and Qingchuan-Wenxian,respectively and areapproximately vertical to the Longmenshan tectonic belt;(3)and so it can be inferred that this blind fault participated in the occurrence process of aftershocks in the north section.更多还原