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Title:: Strong Earthquake Risk Analysis of Xiaojiang Fault Zone and Surrounding Areas

Author(s):: QIAN Xiao-dong; QIN Jia-zheng; (Earthquake Administration of Yunnan Province,Kunming 650224,Yunnan,China)

Keywords:: Xiaojiang fault zone; b-value; seismicity parameter; strong risk zone of earthquake; Yunnan

摘要:: 根据历史地震资料及现今区域台网中小地震观测资料,对小江断裂带及周边地区的历史地震活动特征,特别是小江断裂带不同段落的现今断层活动习性进行了研究,依据b值,结合其它地震活动性参数,勾画出了该区未来强震的潜在危险区:① 石屏—建水断裂段6.8级地震重现期为88～193年,目前已平静121年; 小江断裂带的宜良—嵩明段6.8级地震重现期是108～225年,目前已平静175年。② 小江断裂东川段具有中等偏大应力水平,属于中小地震活动频繁的地段; 小江断裂华宁段具有较低应力水平,属于以小震活动为主的地段; 通海—峨山断裂具有中等应力水平,属于中小地震活动频繁地段。③ 石屏—建水断裂和小江断裂宜良—嵩明段存在较低的b值和较小强震复发周期,具有较高应力水平,属于潜在地震震级偏大的区域,是未来发生7级以上大震的潜在危险区。

Abstract:: According to historical earthquake data and the moderate-small earthquake records from the regional seismic network in Yunnan,we analyze the characteristics of historical earthquakes on Xiaojiang Fault Zone and surrounding areas,especially the current faulting behaviors in the studied area by segment.Based on b-value and other seismicity parameters,we outline the future potential risk zones of strong earthquake:(1)On the Shiping-Jianshui segment,the recurrent period of M6.8 earthquakes is 88-193 years,it has been quiet for 121 years; on the Yiliang-Songming segment,the recurrent period of M6.8 earthquakes is 108-225 years,it has been quiet for 175 years.(2)The Dongchuan segment of the Xiaojiang fault zone has stress level on the high side and frequent moderate-small earthquakes; the Huaning segment has stress level on the low side and low seismicity; the Tonghai-Eshan segment has medium stress level and frequent moderate-small earthquakes.(3)The Shiping-Jianshui segment and the Yiliang-Songming segment have small b-value,short recurrent period of strong earthquakes,high stress level,and large magnitude,so it should be the potential risk zone of M7 earthquakes.