Short-term and imminent geomagnetic anomalies of the Wenchuan M_S8.0 earthquake and exploration on earthquake forecast

作     者：Wuxing Wang Jianhai Ding Surong Yu Yongxian Zhang 

作者机构：Laboratory of Computational Geodynamics Graduate University of Chinese Academy of Sciences Beijing 100049 China Institute of Earthquake Science China Earthquake Administration Beijing 100036 China China Earthquake Networks Center China Earthquake Administration Beijing 100045 China 

出 版 物：《Earthquake Science》 (地震学报（英文版）)

年 卷 期：2009年第22卷第2期

页      面：135-141页

核心收录：

学科分类：070801[理学-固体地球物理学] 07[理学] 0708[理学-地球物理学] 

基　　金：supported by National Key Technologies Research&Development Program of China (Grant No. 2008BAC35B00) 

主　　题：geomagnetic low-point displacement diurnal-variation amplitude Wenchuan earthquake short-term and imminent geomagnetic anomaly forecast of strong earthquakes 

摘      要：The diurnal variation of the geomagnetic vertical component is exhibited mainly by changes of phase and amplitude before strong earthquakes. Based on data recorded by the network of geomagnetic observatories in China for many years, the anomalous features of the appearance time of the minima of diurnal variations （i.e, low-point time） of the geo- magnetic vertical components and the variation of their spatial distribution （i.e, phenomena of low-point displacement） have been studied before the Wenchuan Ms8.0 earthquake. The strong aftershocks after two months＇ quiescence of M6 aftershocks of the Ms8.0 event were forecasted based on these studies. There are good correlativities between these geomagnetic anoma- lies and occurrences of earthquakes. It has been found that most earthquakes occur near the boundary line of sudden changes of the low-point time and generally within four days before or after the 27th or 41st day counting from the day of the appearance of the anomaly. In addition, the imminent anomalies in diurnal-variation amplitudes near the epicentral areas have also been studied before the Wenchuan earthquake.