通海地磁Z分量拟合差及月距平与云南强震危险性分析

Strong Earthquake Risk Analysis in Yunnan Based on Fitting Residual and Monthly Mean of Geomagnetic Z-component in Tonghai

对1986年以来的通海地磁相对观测Z分量月均值资料进行拟合及月距平分析发现,云南地区M≥6.0强震发生前,通海地磁Z分量速率变化显著,具有加速上升或加速下降的变化特征。2009年3月至2010年6月出现加速上升48.5 nT异常变化,持续时间达15个月,由震例统计及指标显示,未来1年或稍长时间,云南地区存在发生6级左右甚至7级地震的危险。

Through fitting and monthly-anomaly analysis of the monthly mean value of the relative geomagnetic Z-com- ponent at Thonghai station since 1986, we find an evident variation of velocity of Z-component--accelerated rise or fall before the M≥6.0 earthquakes in Yunnan. From March 2009 to June 2010, the velocity of Z-component acceleratedly rose for 48.5nT and the duration lasted for 15 months. According to the statistics of earthquake cases in Yunnan and the earthquake-prediction indexes, we conclude that there exists a risk of earthquake with M6. 0 or even M7.0 in one year or some time longer.