断裂带同震温度负异常机制分析  

Analysis on the mechanisms of coseismic temperature negative anomaly in fault zones

作　　者：杨小秋[1,2,3] 林為人 葉恩肇 许鹤华 徐子英[7] YANG XiaoQiu;LIN Weiren;YEH En-Chao;XU HeHua;XU ZiYing(Chinese Academy of Sciences Key Laboratory of Ocean and Marginal Sea Geology,South China Sea Institute of Oceanology,Guangzhou 510301,China;Innovation Academy of South China Sea Ecology and Environmental Engineering,Chinese Academy of Sciences,Guangzhou 510301,China;Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,China;Graduate School of Engineering,Kyoto University,Kyoto 615-8540,Japan;Kochi Institute for Core Sample Research,Japan Agency for Marine-Earth Science and Technology,Nankoku,Kochi 783-8502,Japan;Department of Earth Sciences,National Taiwan Normal University,Taibei 11677,China;Key Laboratory of Marine Mineral Resources,Ministry of Nature Resources,Guangzhou Marine Geological Survey,Guangzhou 510075,China)

机构地区：[1]中国科学院边缘海与大洋地质重点实验室,南海海洋研究所,广州510301 [2]中国科学院南海生态环境工程创新研究院,广州510301 [3]南方海洋科学与工程广东省实验室(广州),广州511458 [4]Graduate School of Engineering,Kyoto University,Kyoto 615-8540,Japan [5]Kochi Institute for Core Sample Research,Japan Agency for Marine-Earth Science and Technology,Nankoku,Kochi 783-8502,Japan [6]台湾师范大学地球科学系,中国台北11677 [7]自然资源部海底矿产资源重点实验室,广州海洋地质调查局,广州510075

出　　处：《地球物理学报》2020年第4期1422-1430,共9页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41874099,41474065,41981240687,41606080);日本科学技术研究经费支援项目(JSPS KAKENHI Grant Number JP16H04065);南方海洋科学与工程广东省实验室(广州)人才团队引进重大专项(GML2019ZD0104);中国台湾科技部项目(MOST 106-2116-M-003-003)资助.

摘　　要：断裂带同震温度响应,可在震后钻孔测温中获得并识别,为发震断层摩擦特性与发震机制等基础研究提供了非常独特的思路和有效手段.集集、汶川及日本东北大地震后,实施了台湾车笼埔断层钻探项目(TCDP)、汶川地震断裂带科学钻探工程(WFSD)和日本海沟快速钻探计划(JFAST).钻孔测温结果表明:滑移面上下5~20m范围内存在温度正异常,这是同震摩擦生热所致,该机制已被广泛认识和接受;同时,距滑移面20~60m范围内也存在明显的温度负异常,但其成因机制几乎还未被真正关注和认识.虽然温度负异常峰值只有正异常峰值的1/4~1/3,但温度负异常分布范围却是正异常分布范围的3~4倍,即正、负温度异常区对应的总能量基本相当.因此,断裂带震后钻孔测温中的负异常及其成因不容忽视.在详细分析几种可能的同震温度负异常机制后(如岩层热物性分布差异、流体运移、表面自由能增大及同震应力释放),发现能在理论、实验及野外观测上都得到支撑的普适性机制只有同震应力释放.这可能是断裂带震后温度负异常的主要原因.The coseismic temperature responses can be recognized in the borehole temperaturemeasurements in fault zones after earthquakes.It provides a unique idea and an effective mean for basic research about the friction features and seismogenic mechanisms of fault zones.Borehole temperature measurement results show that there were both positive and negative temperature anomalies that followed the 1999 Chi-Chi,2008 Wenchuan and 2011 Tohoku earthquakes.The positive temperature anomaly(within 5~20 m away from fault slip surfaces)has been well known because of the frictional heating that occurred during coseismic faulting.However,the negative temperature anomaly(range of 20~60 mfrom fault slip surfaces)still has not been noted and expressly addressed.The amplitude of the negative temperature anomaly is 1/4~1/3 of that of the positive temperature anomaly;but the range of the negative temperature anomaly are 3~4 times of that of positive anomaly.In that case,the total of energy in the negative and positive areas is basically the same.Therefore,the negative anomalies in borehole temperature measurement and their causes can no longer be ignored.After a detailed analysis of several possible mechanisms of coseismic temperature negative anomalies(i.e.,differences in distribution of thermal properties,fluid migration and increase of surface free energy),it is found that only coseismic stress release is a universal mechanism that can be supported in theory,experiment and field observation.This may be the main reason for the negative temperature anomaly in fault zones after earthquakes.

关 键 词：同震温度响应机制 应力释放 表面自由能 摩擦生热 集集地震 汶川地震 日本东北地震 

分 类 号：P314[天文地球—固体地球物理学]