2001年三次6级左右地震前西昌地磁的虚假异常研究

Study on False Geomagnetic Anomalies in Xichang before the Three Earthquakes with about M6 in 2001

20 0 1年 ,在西昌地磁台 30 0km范围内连续发生了三次 6级左右地震 ;即 2月 2 3日在西昌西北 2 0 0km的四川雅江县境内发生的 6 0级地震 ;5月 2 4日在西昌西南 14 0km的盐源县境内发生的MS5 8地震 ;10月 2 7日在西昌西南 2 6 0km的云南永胜发生的MS6 0地震。震前 ,西昌地磁台各相对观测记录分量和绝对观测量都发生了明显的异常变化。研究结果表明 ,由于邻近基建施工 ,使观测环境发生改变 ,引起大幅度虚假异常 ,这些异常尽管与三次地震对应较好 ,但不是前兆异常。

In 2001,the three earthquakes,the M 6 0 earhquake on February 23,the M S 5 8 earthquake on May 24 and the M S 6 0 earthquake on October 27 occurred in Yajiang,Sichuang,200km northwest of Xichang,Yanyuan,Sichuang 140km southwest of Xichang and Yongsheng,Yunnan,260 km southwest of Xichang,respectively.The study results show that variation in observation environment due to civil construction working induced large false anomalies,which were not precursor anomalies although they were in good corresponding to the three earthquakes.