岷县-漳县M_S6.6地震前重力分形指数异常分析

The Anomaly of Fractal Exponent on Gravity before the Minxian-Zhangxian M_S6.6 Earthquake

以2013-07-22甘肃岷县与漳县交界的MS6.6地震为研究对象,采用去趋势波动分析方法处理兰州、高台2个台2011~2015年重力观测资料,试图提取这次地震前的相关重力异常信息。结果表明,以9.4倍的该台分形指数标准差为异常阈值,岷县-漳县地震前这2个台的重力分形指数均出现相似的异常升高过程,表明震前重力变化具有定向持续特征,显示出长程相关性,是孕震过程中物质运移、密度连续变化的反映,应该是与这次地震有关联的重要信息。结合其他学者的研究结果初步推测,这个异常变化可能与中下地壳乃至上地幔的物质运移有关。

In this study,we use gravity observation data from two stations in Lanzhou and Gaotai from 2011 to 2015.The M S 6.6 earthquake,which occurred at the junction of Minxian and Zhangxian on July 22,2013,is taken as the research object.The detrended fluctuation analysis method is used to deal with the continuous observation data of the two stations,and to try to extract anomaly information on gravity before the earthquake.The results show,with 9.4 times the standard deviation of the fractal index of the station as abnormal threshold,that there is a similar abnormal increase process before the earthquake on the gravity fractal index of the two stations.This indicates the gravity variation before the earthquake,has a continuous feature and shows a long-range correlation.This may be important information related to the earthquake.The study of this gravity fractal exponent is only preliminary and exploratory.Combined with the research results of other scholars,it is preliminarily speculated that this abnormal change may be related to the material migration in the middle and lower crust and even the upper mantle.