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由现今地震活动分析鲜水河断裂带中—南段活动习性与强震危险地段 预览 被引量:39

Study on faulting behavior and fault-segments for potential strong earthquake risk along the central-southern segment of Xianshuihe fault zone based on current seismicity
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摘要 利用最近25年的区域台网地震资料, 基于沿鲜水河断裂带中-南段的b值分布以及多个地震活动参数值的不同组合, 结合震源深度分布、历史强震背景等, 分析了不同断裂段落的现今活动习性, 进而初步判别该断裂带潜在的强震危险地段. 结果表明, 鲜水河断裂带中-南段目前存在6个不同活动习性的段落. 其中, 道孚段自1981年强震后已再次趋于闭锁, 原因可能与断层面存在'凹凸体'有关, 但应变可能还会进一步积累; 八美段目前处于中偏高应力下的相对静止状态, 推测其断面正处于新的应力积累阶段; 塔公段已有255~300年的无强震期, 目前正处于高应力下的相对闭锁状态, 震源深度剖面上的小震空白区显示出闭锁断层面的轮廓, 应属于未来最可能发生强震的危险地段; 康定、磨西二个段落表现出中偏低应力下的稀疏小震滑动及较频繁小震滑动的状态, 意味着最晚的一次大地震破裂后断层面尚未重新耦合; 石棉段表现出偏高应力下的频繁中-小地震活动与该段的多条断裂交汇有关. In this paper, using the present seismic data from the regional network for the last 25 years and combing with the analysis of depth distribution of relocated hypocenters and historical strong earthquake sources along the central-southern segment of the Xian-shuihe fault zone, the authors have studied the current faulting behaviors on different segments of the fault zone, and preliminarily identified the risky fault-segments on which potential strong earthquakes would occur in the near future, based on distribution of b-values along the fault zone and various combinations of values of multiple seismicity parameters on the different fault-segments. The results show that the studied fault zone currently has six segments showing different faulting behavior. Of which, the Daofu segment has tended to be locked again since the 1981 strong earthquake, and the reason could be that the fault plane there probably has an asperity. It seems to need more time to build-up strain. The Bamei segment is now situated in the state of relative rest under middle to high stress, such a state can be explained as that the fault plane is being on its new stage for stress accumulation. The Tagong segment has no strong earthquake occurred for 255 to 300 years. And now is behaving locked under relatively high stress. A gap of current small-quakes on the profile of hypocenter depth seems to outline the locked fault plane of this segment. These suggest that the Tagong segment should be the most possible section of the fault zone for a potential strong earthquake occurring in the near future. The Kangding and Moxi segments are behaving weak slipping of sparse small-quakes and slipping of denser small-quakes respectively, under middle to low stress, showing that the fault planes have not yet re-coupled since the latest large earthquake rupture on the both segments. The Shimian segment displays frequent small-quake activity under middle to high stress, which is probably associated with the locality being at a junction area of several branch faul
作者 易桂喜 范军 闻学泽 YI Gui-xi,FANG Jun,WEN Xue-ze
出处 《地震》 CSCD 北大核心 2005年第1期 58-66,共9页 Earthquake
基金 地震科学联合基金
关键词 鲜水河断裂带 地震活动 断层面 强震 震源深度 大地震 台网 高应力 闭锁 断面 Seismicity parameter Faulting behavior Strong-earthquake risk Xian- shuihe fault zone
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