SEISMOLOGY AND GEOLOGY ›› 2015, Vol. 37 ›› Issue (1): 307-318.DOI: 10.3969/j.issn.0253-4967.2015.24

• CONTENTS • Previous Articles     Next Articles

UNDERGROUND FLUID ANOMALIES AND THE PRECURSOR MECHANISMS OF THE LUDIAN MS6.5 EARTHQUAKE

LIU Yao-wei1, REN Hong-wei1, ZHANG Lei1,2, FU Hong3, SUN Xiao-long1, HE De-qiang4, YU Huai-zhong5, ZHOU Zhi-hua5, ZHANG Guo-meng1   

  1. 1 Key Laboratory of Crustal Dynamics, Institute of Crustal Dynamics, China Earthquake Administration, Beijing 100085, China;
    2 Institute of Geophysics, China Earthquake Administration, Beijing 100081, China;
    3 Yunnan Earthquake Administration, Kunming 650224, China;
    4 Zhaotong Earthquake Prevention and Disaster Reduction Administration, Zhaotong 657000, China;
    5 China Earthquake Networks Center, Beijing 100045, China
  • Received:2014-11-03 Revised:2015-01-23 Published:2015-05-15

鲁甸6.5级地震地下流体典型异常与前兆机理分析

刘耀炜1, 任宏微1, 张磊1,2, 付虹3, 孙小龙1, 何德强4, 余怀忠5, 周志华5, 张国盟1   

  1. 1 中国地震局地壳应力研究所, 地壳动力学重点实验室, 北京 100085;
    2 中国地震局地球物理研究所, 北京 100081;
    3 云南省地震局, 昆明 650224;
    4 昭通市防震减灾局, 昭通 657000;
    5 中国地震台网中心, 北京 100065
  • 通讯作者: 任宏微,电话:010-62842631,E-mail:renhongweiwei@163.com。
  • 作者简介:刘耀炜,男,1957年生,研究员,主要研究方向为地下流体动力学与地震监测预报,电话:010-62911045,E-mail:liuyw20080512@126.com。
  • 基金资助:

    中国地震局"云南鲁甸6.5级地震专题研究"项目资助

Abstract:

We summarized the fluid anomalies associated with the Ludian MS6.5 earthquake based on the Sichuan and Yunnan earthquake network observations and field survey. The fluid anomalies were divided into long-term, medium-term, short-term, imminent and macroscopic anomalies according to the basic principles of earthquake forecasting. The long-term and medium-term anomalies distributed mainly in the range 300~500km away from the epicenter. By contrast, the short term, imminent and macroscopic anomalies clustered in an epicentral distance less than 100km. The underground fluid anomalies in the higher station density area reflect the enhancement of fluid movement, which are conducive to determine the seismic risk area and trace the short-term precursor of earthquake. The regional stress variations may cause the fractures in a fault zone open and close, leading to the change of water level and temperature in boreholes or spring and emission of deep-sourced gases. It may also lead to intense water-rock reaction and groundwater intrusion, resulting in the change of ion contents in groundwater, or sometimes, the occurrence of significant macroscopic anomalies. Therefore, it is highly possible to obtain reliable earthquake precursor information for predicting the forthcoming earthquake risk zone in the region with dense observation stations.

Key words: Ludian MS6.5 earthquake, underground fluid, anomaly information, precursor mechanism, earthquake survey

摘要:

基于川滇地区前兆台网资料, 结合异常现场核实工作结果, 对鲁甸6.5级地震前的地下流体异常现象进行了总结。遵循地震分析预报的基本思路, 按照长期、中期、短期趋势异常、临震异常和宏观异常阐述了鲁甸6.5级地震前地下流体典型异常现象。结果表明, 长期和中期趋势背景异常主要出现在距震中300~500km范围, 短期趋势和临震及宏观异常集中于震中区100km范围内。这种流体异常特征反映了在较高密度的观测点区域, 可以观测到流体活动加剧的前兆现象, 有利于判定地震危险区和短期阶段跟踪分析。区域应力加载作用可能引起的断裂带裂隙的开启与闭合, 导致温泉和井水温、深部气体与承压井水位的持续变化;水岩反应加剧和地下水混合作用增强, 使地下水离子组分浓度发生变化, 甚至导致显著宏观异常。在一定密度的前兆观测地区, 能够获取用于判定地震危险性的前兆信息。

关键词: 鲁甸6.5级地震, 地下流体, 异常信息, 前兆机理, 地震科考

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