地磁场与电离层异常现象及其与地震的关系

利用中国地磁台网与电离层台站资料，总结了大地震前出现的地磁低点位移、地磁日变异常及电离层f0F2（F2层临界频率）异常现象．对比研究了1997年11月8日玛尼7．5级与2001年11月14日昆仑山口西8．1级地震前磁场与电离层异常分布及特征．结果显示，两次巨大地震前磁场与电离层短临异常时空分布特征有较好的一致性，震中周围出现日变异常、拉萨台出现电离层f0F2明显异常；震前约1个月出现地磁低点位移，其突变分界线通过震中地区．

Phenomena of Geomagnetic and Ionospheric Anomalies and Their Relation to Earthquakes

On the basis of data from the geomagnetic network and ionospheric observatories in China, the geomagnetic low point displacement, diurnal variation anomalies of geomagnetic field and ionospheric f_0F_2 (critical frequency of F_2 layer) anomaly phenomena before large earthquakes have been summarized. Anomaly distribution and characteristics of geomagnetic variation field and ionospheric f_0F_2 before Mani MS 7.5 earthquake on Nov.8, 1997, and Kunlunshan MS 8.1 earthquake on Nov. 14, 2001, have been comparatively studied. The result shows that the temporal spatial characteristics of short term and imminent anomalies of geomagnetic field and ionosphere are consistent. The obvious anomalies of diurnal variation of geomagnetic field near epicentral area and ionospheric f_0F_2 at Lhasa observation are found. The geomagnetic low point displacements appeared about one month before the two great earthquakes, the boundary lines of sudden change passed through the epicentral area.