| 川西地区长周期气温变化对跨断层位移观测的影响及芦山地震前的异常断层活动 |
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| 引用本文： | 刘冠中,马瑾,杨永林,苏琴.川西地区长周期气温变化对跨断层位移观测的影响及芦山地震前的异常断层活动[J].地球物理学报,2014,57(7):2150-2164. |
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| 作者姓名： | 刘冠中 马瑾 杨永林 苏琴 |
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| 作者单位： | 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. 中国地震局地质研究所地震动力学国家重点实验室, 北京 100029;3. 四川省地震局测绘工程院, 雅安 625000 |
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| 基金项目： | 中国地震局地壳应力研究所基本科研业务专项(ZDJ2011-18);国家自然科学基金(41172180,41204005)共同资助 |
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| 摘 要： | 2013年4月20日四川芦山M7.0级地震前2-3年，川西地区的跨断层位移出现群体性、准同步的异常趋势转折，但有些场地的辅助气温观测也呈现相似变化.为探寻这些趋势转折是否为热形变，本文基于鲜水河、安宁河-则木河、龙门山断裂带上的短基线、短水准及辅助气温观测数据，使用频谱分析及统计分析方法，研究跨断层位移与气温之间的关系，并利用主模式分析方法研究芦山地震前各断裂带的运动特征.结果显示：（1） 在大于2.63 a的周期上，短基线、短水准与气温的频率成分较为相似，它们之间为弱-中等强度的相关.（2） 气温变化不是芦山地震前跨断层位移发生趋势转折的主要影响因素.除个别场地外，长周期热形变在总的跨断层位移中所占比重较小，对其趋势变化的影响有限.（3） 主模式分析表明，2010年前后，鲜水河断裂带的左行走滑和张性运动有所减弱，安宁河-则木河、龙门山断裂带的张性运动也开始减弱（或者说压性增强）.这些变化特征可能反映了在这一时期巴颜喀拉块体SE-SEE向运动的加剧.
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| 关 键 词： | 芦山地震 断层位移 趋势转折 热形变 异常 |
| 收稿时间： | 2013-07-15 |
Effect of long-term surface temperature variation on fault displacement observation and anomalous fault movement in Western Sichuan before the Lushan MS7.0 earthquake |
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| LIU Guan-Zhong,MA Jin,YANG Yong-Lin,SU Qin.Effect of long-term surface temperature variation on fault displacement observation and anomalous fault movement in Western Sichuan before the Lushan MS7.0 earthquake[J].Chinese Journal of Geophysics,2014,57(7):2150-2164. |
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| Authors: | LIU Guan-Zhong MA Jin YANG Yong-Lin SU Qin |
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| Institution: | 1. Key Laboratory of Crustal Dynamics, Institute of Crustal Dynamics, China Earthquake Administration, Beijing 100085, China;2. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;3. Survey Engineering Institute, Earthquake Administration of Sichuan Province, Ya'an Sichuan 625000, China |
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| Abstract: | About 2~3 years before the Lushan MS7.0 earthquake on 20 April 2013, some short-baseline and short-leveling sites in western Sichuan presented long-term and quasi-synchronous trend transition. However, the temperatures from some auxiliary observation were similar to fault displacements in some extent. So, in order to explore if they are thermal deformation, we analyze the short-baseline, short-leveling, and temperature observation data from Xianshuihe, Anninghe-Zemuhe, and Longmenshan fault zone. Based on spectrum and statistical analysis methods, the correlation between fault displacement and temperature is studied. Furthermore, the movement features of these fault zones are discussed by using principal mode analysis. The results show that: (1) In the period of larger than 2.63 years, the fault displacement and temperature data have similar frequency components, and have weak to moderate correlation. (2) The variation of temperature is not the major influence factor on the trend transition of fault displacement before Lushan earthquake. Except individual site, the secular thermal deformation only contributes a small fraction in the whole deformation. (3) The principal mode analysis suggests that, around 2010, the left-lateral strike slip and tensional movement weakened along Xianshuihe fault zone, and the tensile motion of Anninghe-Zemuhe and Longmenshan fault zone weakened also. These variation features may be associated with the intensive movement in SE-SEE orientation of the Bayan Har tectonic block in this stage. |
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| Keywords: | Lushan earthquake Fault displacement Trend transition Thermal deformation Anomaly |
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