玉树地震前的电离层异常现象分析

分析了玉树地震前地基电离层探测临界频率、GPS TEC和卫星探测原位等离子体参量等多个参数的扰动变化信息, 研究了不同高度异常变化的时空关联性. 分析发现, 在地震前一天的4月13日, 多个电离层参量出现同步扰动异常, 电离层临界频率f₀F₂异常相对滑动中值增大40%, 异常空间上存在从震中东南向西南漂移的特性; GPS TEC异常增强15TECU (1TECU=1016m-2)左右, 分布于震中南部经度15°范围内, 且有明显的磁共轭效应; DEMETER观测的原位氧离子密度N_i(O+) 4月13日为1-4月中最强的一天, 异常分布偏向赤道区, 但仅局限在30°-50°左右的经度范围内. 综合三个参量的异常特征发现, 无论是空间的局地性还是时间上的密切关联均反映这次电离层扰动可能与玉树地震孕育有关. 结合其他观测信息, 进一步探讨了这次地震孕育过程的地震电离层耦合机理. 

Analysis on Ionospheric Perturbations before Yushu Earthquake

In this paper, the ionospheric perturbations in three parameters have been analyzed around Yushu earthquake, including f₀F₂ from ionosonde, GPS TEC, and in-situ plasma parameters by satellite. Their temporal and spatial relationship with this event were studied, and the results showed synchronous disturbances in multi-parameters on 13 April, just one day before the Yushu earthquake. The f₀F₂ abnormally increased 40% relative to its sliding median of 5 days before, and its anomalous center moved from southeast to southwest. GPS TEC with abnormal amplitude of 15TECU (1TECU=1016m-2) concentrated in a longitudinal scale of 15° over the south of the epicenter, and similar anomalies were found at its conjugate areas. While the in-situ observation of oxygen ion density N_i(O+) from DEMETER reached its maximum on April 13 for the four months from January to April in 2010, with the anomalies deviating to the equatorial areas but limited in the longitude scale of 30°-50°. Su mming up the anomalous characteristics in these three parameters, whatever the local feature in space, or the close relevance in time, both exhibited possible relationship with the Yushu earthquake. Combined with other observations, the seismo-ionospheric coupling mechanism was discussed during the preparation process of Yushu earthquake.