中国西北地区强震前地磁短期异常特征分析
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摘要
通过对祁连山中东段及共和盆地近几年来发生的５级以上地震前地磁异常特征及其时空分布特征分析，研究了中国西北地区强震的地磁短期异常特征和预报指标．结果表明，磁暴、低点位移和地磁垂直分量的相关性在强震前均出现了不同程度的异常．发震时间距低点位移异常开始的时间在１个月内，距磁暴出现的时间为倍九日期的±３天内．发震地点一般位于低点位移异常形成的分界线附近或低点位移异常所围绕的某个区域内．若相关系数异常持续５个月以上，在异常区内有发生中强地震的可能
Analysing characteristics of geomagnetic anomalies before M S≥5 earthquakes in recent years in Gonghe basin and at middle east section of Qilian mountains and space time distribution of the anomalies,geomagnetic short term prediction indexes before strong earthquakes in northwestern China are studied.The results indicate that various degrees of anomalies of magnetic storm,geomagnetic low value displacement and correlation coefficients of geomagnetic vertical component between stations appeared before strong earthquakes.Interval from beginning of geomagnetic low value displacement anomalies to origin time is 10～40 days.Interval from magnetic storm to origin time is three days before and after the dates which are multiple of nine.Coming earthquakes are located at near line of demarcation of the low value displacement anomalies,or in the anomalous area.If duration of the correlation coefficient anomalies is over 5 months,it is possible that M S≥5 earthquake occurs in anomalous area.
Analysing characteristics of geomagnetic anomalies before M S≥5 earthquakes in recent years in Gonghe basin and at middle east section of Qilian mountains and space time distribution of the anomalies,geomagnetic short term prediction indexes before strong earthquakes in northwestern China are studied.The results indicate that various degrees of anomalies of magnetic storm,geomagnetic low value displacement and correlation coefficients of geomagnetic vertical component between stations appeared before strong earthquakes.Interval from beginning of geomagnetic low value displacement anomalies to origin time is 10～40 days.Interval from magnetic storm to origin time is three days before and after the dates which are multiple of nine.Coming earthquakes are located at near line of demarcation of the low value displacement anomalies,or in the anomalous area.If duration of the correlation coefficient anomalies is over 5 months,it is possible that M S≥5 earthquake occurs in anomalous area.
引文
〕张苏平．中国西部地区地磁低点位移异常和磁暴与中强地震的关系〔J〕．西北地震学报，1995，17（3）：88～89．
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