2013年7月22日甘肃岷县—漳县6.6级地震地磁总场F空间相关异常分析

Analysis of Spatial Correlation Anomaly in the Geomagnetic Total Field F Component during the Gansu Province Minxian—Zhangxian 6.6 Earthquake on July 22, 2013

摘要:

利用甘肃岷县—漳县6.6级地震震中距在1 000 km范围内的33个地磁台站地磁总场F₀₂点值，研究其空间相关系数在地震前后的变化。结果显示：（1）在本次地震前共有15个地磁台站存在空间相关低值异常，该异常平均持续22天；（2）异常幅度在一定程度上随着震中距的增大而减小；（3）在异常持续过程中，异常最低值时间基本统一；（4）异常起始时刻至发震时刻的平均时间间隔为54天，异常结束时刻至发震时刻的平均时间间隔为33天，该异常具有短期效应。并且，异常台站分布与该区域构造走向、余震震中和极震区展布有一定相似性，虽然存在地磁台站分布不均匀的客观事实，但该现象为研究地磁异常分布与构造之间的联系提供了素材。

Abstract:

In this paper, we analyze the geomagnetic total field F component at the 02 point value for stations located in the 1000-km range of the epicenter of the Minxian 6.6 earthquake. We determined the changes in the spatial correlation coefficient with respect to the F component before and after the earthquake. Our results showed that: 1) 15 stations had a low spatial correlation prior to the earthquake and the average abnormal phenomenon lasted 22 days; 2) the anomalous amplitude decreased as the epicentral distance increased to a certain extent; 3) in the process of continuous abnormity, the minimum value time was uniform; 4) the average interval time was 54 days from the start of abnormity to the original time of the earthquake and 33 days from the end of abnormity to the original time of the earthquake. This anomaly had short-term effects. In addition, the locations of the abnormal stations have a certain similarity with respect to their regional structure trends, epicenters of the aftershock, and their magistoseismic area distributions. Although the uneven distribution of geomagnetic stations is an objective fact, this phenomenon provides some material for the study of the relationship between geomagnetic anomaly distribution and structure.