断层发震时应力释放的温度响应

项目名称： 断层发震时应力释放的温度响应

项目编号： No.41474065

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 天文学、地球科学

项目作者： 杨小秋

作者单位： 中国科学院南海海洋研究所

项目金额： 87万元

中文摘要： 摩擦系数是研究断层发震机制的基础参数.而断层同震温度异常,因可在震后钻孔测温中识别并获得,从而为断层摩擦特性和发震机制等基础研究提供了非常独特的思路和有效手段.一直以来,摩擦生热被认为是断层同震温度异常的唯一原因.但同震应力瞬间释放,定会引起内能减小,导致温度降低.这一效应,不仅有绝热减压理论支持,且在岩石加/卸压与温度响应试验和断裂带震后钻孔温度数据中都得到证实.因此,同震温度异常受摩擦生热和应力释放致温度降低的共同影响.为此,本申请拟基于车笼埔断裂带TCDP钻孔、龙门山断裂带WFSD钻孔及日本海沟俯冲带JFAST钻孔测温数据,通过建立同震应力释放和温度响应的有限元数值模型,深入开展断层同震温度响应机制研究,将摩擦热和同震应力释放导致的温度异常加以区分,以便准确估算各断裂带发震时摩擦热和摩擦系数.这为深入了解断裂带摩擦特性、发震机制及地震能量分配提供理论依据,对今后防震减灾具有指导意义.

中文关键词： 同震应力释放；温度响应；发震断层；热应力系数；热导率

英文摘要： The friction coefficient of the seismic fault during slip controls earthquake dynamics. The coseismic temperature anomaly of fault, which can be identified and obtained by analyzing borehole temperature after earthquake, provides an unique idea and an effective mean for friction features of fault and basic research seismogenic mechanism. For a long time, the friction heat generated during earthquake faulting is considered to be the only reason for the coseismic temperature anomaly. But coseismic stress release instantaneously can lead internal energy decreasing which results in the temperature decrease. This effect can be not only supported by the theory of adiabatic decompression, but also proved to be correct in experiment about the temperature response test when pressure loading and unloading to rock and in borehole temperature data after earthquake.Thus, coseismic temperature anomaly can be caused by the combined impact of the friction heating and coseismic stress releasing instantaneously. For this reason, this application of the research project based on the borehole temperature data from TCDP hole in Chelongpu fault zone, WFSD hole in longmenshan fault zone and the JFAST hole-C0019 in Japan Trench subduction zone, through the establishment of finite element numerical model of coseismic stress release and temperature response, we can understand better about the mechanism study on coseismic temperature response and identify the temperature anomalies caused by coseismic stress release and frictional heat. And we can accurately estimate seismogenic friction heat and coefficient of dynamic friction of fault zone during slip. This work provide theoretical basis for better understanding friction features , the seismogenic mechanism and seismic energy distribution which has guiding significance for protecting against and mitigating earthquake disasters in the future.

英文关键词： coseismic stress release;temperature response;seismic faults;thermal stress coefficient;thermal conductivity