2014年云南盈江6.1和鲁甸6.5级地震前地磁垂直分量日变化空间相关异常特征

Spatial Correlation Anomalies of Geomagnetic Vertical Component Diurnal Variation before Yingjiang M6.1 and Ludian M6.5 Earthquakes

2014年5月30日、8月3日中国西南地区(22~42°N,94~113.5°E)相继发生了盈江6.1级、鲁甸6.5级地震,在这两次地震之前位于该区域地磁台站观测数据存在显著的异常变化。本文主要采用地磁垂直分量日变化空间相关方法对西南地区地磁数据进行了处理,以提取异常时空特征。结果显示:(1)4月1日至5月20日南山、木里、贵阳、河池和邕宁五个地磁台站与新沂、红山之间相关系数曲线出现准同步的下降变化,异常结束3个月内,西南地区相继发生这两次地震。(2)对异常期间西南地区进行地磁垂直分量日变化空间相关空间扫描发现,经去除背景值和归一化之后的相关系数等值线图中出现了有别于背景分布的高梯度带(范围为0.4~0.6),盈江6.1级、鲁甸6.5级地震震中分别位于该梯度带内及其附近区域。

There are significant anomalies at the geomagnetic stations in southwest region of China before the 2014 Yingjiang M6.1 earthquake and the Ludian M6.5 one. We pro- cessed the geomagnetic vertical component diurnal variation data by the spatial correlation method. The results show that, during the period from 1st April to 20th May, there existed quasi-synchronous decrease changes in coefficient curves between the five geomagnetic stations including Guiyang, Hechi, Nanshan, Muli, Yongning and the Xinyi and Hongshan stations. Furthermore, there was a high gradient zone in the normalized correlation coefficient contour map with background values removed. The epicenters of the Yingjiang M6.1 earthquake and the M6.5 Ludian earthquake were respectively located in the gradient zone or near the gradient zone.