【摘要】 在采用HYPODD方法对汶川地震序列精确定位的基础上,利用CAP方法反演了龙门山断裂带北川以北段5级以上余震的震源机制解,讨论了该段的震源分布特征和强余震的破裂复杂性。结果显示,汶川余震序列的震源深度沿龙门山断裂带走向从汶川映秀至平武南坝有逐渐变浅的趋势,且震中沿映秀-北川-南坝地震地表破裂带分布;在该断裂带的北川以北段,余震序列具有更次级的分段活动特点,5.5级以上强余震发生在余震带走向的端部或者拐折、错位的部位;7次5.5级以上强余震中有4次以逆冲破裂为主,3次以走滑破裂为主,可能是北川-青川断裂、平武-青川等4条断裂参与了余震活动过程。更多还原

【Abstract】 On the basis of precise locations of the Wenchuan earthquake sequence by using the HYPODD method,the focal mechanisms of the aftershocks(M≥5.0) occurred on the Longmenshan fault zone north to Beichuan were inversed by using the CAP method and the characteristics of hypocenter distribution and rupture complexity of strong aftershocks are discussed.The results are that the focal depth of Wenchuan aftershock sequence decreased gradually from Yingxiu of Wenchuan to Nanba of Pingwu along Longmen Shan fault zone,which beyond the segment boundary located in Beichuan,and the epicenters were distributed along the Yingxiu-Beichuan-Nanba coseismic surface rupture zone in the Central Fault.The aftershock sequence was characterized as less secondary segmented activity in Central Fault Zone north to Beichuan.The aftershocks(M≥5.5) were occurred on the end,transition or dislocation of the aftershocks zone.According to the focal mechanism,four of the seven stronger aftershocks are thrust and the others are strike-slip,it may suggest that the process of the aftershock activity was related to the Beichuan-Qingchuan Fault,Pingwu-Qingchuan Fault etc.更多还原