摘要
许多学者认为2008年汶川8级地震可能对龙门山断裂带及其周围不同断裂带上后续发生的6级以上地震有一定的影响.本文以地震应变场作为地震活动的变量,通过自然正交函数展开方法,研究2008年以来龙门山断裂带周围5次6级以上地震前的地震应变场,提取出震前应变场时空异常的变化.结果表明:(1)2008年汶川8.0级地震前和2013年芦山7.0级地震前地震应变场时间因子分别出现明显的中短期异常和短临异常;而2013年岷县漳县6.6级地震前、2014年康定6.3级地震前和2017年九寨沟7.0级地震前地震应变场时间因子中短期异常不明显,分析其原因主要是受到2008年汶川8.0级地震应变场时间因子最大幅度异常的影响.(2)研究应变场时间因子对应的区域空间等值线变化,发现2009年以后地震应变场空间等值线高值异常区以及异常区周围发生的强震,均可能受到2008年汶川8.0级地震应变场的影响.(3)最后分析1970年以来龙门山断裂带周围地震应变的空间演化过程,总结强震应变变化特征的发震模式,从地震应变演变角度探讨强震之间的相互影响,以及断裂带所在块体间的相互牵制和调整作用.
Many scholars believe that the magnitude 8 Wenchuan earthquake in 2008 May have a certain impact on the subsequent earthquakes above magnitude 6 in Longmenshan fault zone and the surrounding different fault zones.In this paper,the seismic strain field is used as the variable of seismic activity.We calculate the seismic strain field before 5 earthquakes of over M 6 above the Longmenshan Fault zone since 2008 using the natural orthogonal function expansion method.Then,we study on the change of time and space anomaly of strain field before earthquake.Results indicate that:(1)The time factors of the earthquake strain field before the Wenchuan M 8.0 2008 and the Lushan M 7.0 2013 respectively have obvious medium-short term anomalies and short-impending anomalies.The time factors of the earthquake strain field in short-term anomaly before Minxian-Zhangxian M 6.6 2013,the Kangding M 6.3 2014 and Jiuzhaigou M 7.0 2017 is not obvious.It is mainly affected by the maximum amplitude anomaly of the strain field time factor of the Wenchuan M 8.0 2008.(2)Analyzing of anomalous changes in space corresponding to their time factors,it is found that the high value anomaly area of seismic strain field and the 4 strong earthquakes surrounding the anomaly area after 2009 are all affected by the strain field of the Wenchuan M 8.0 2008.(3)Finally,we analyze the spatial evolution process of the seismic strain energy around the Longmenshan fault zone since 1970,and summarize the seismogenic mode of the variation characteristics of the 5 strong earthquake strain energy.From the evolution of the seismic strain energy,we discuss the interaction between strong earthquakes,the interaction and adjustment of the block.
作者
罗国富
柳忠旺
罗恒之
丁风和
LUO Guo-fu;LIU Zhong-wang;LUO Heng-zhi;DING Feng-he(Earthquake Administration of Ningxia Hui Autonomous Region,Yinchuan 750001,China)
出处
《地球物理学进展》
CSCD
北大核心
2019年第3期908-918,共11页
Progress in Geophysics
基金
地震科技星火计划项目(XH18052)资助
关键词
地震应变场
自然正交函数展开方法
时间因子异常
空间等值线异常
The seismic strain field
Natural orthogonal function expansion method
Time factor abnormality
Spatial contour anomaly
