中文摘要：

基于GPS TEC数据,对1998年11月1日—2010年12月31日中国大陆M_s≥6.0地震临震电离层扰动进行了研究.分析发现,震中上空及周围的东、南、西、北4个方向震前15天到地震当天时序变化趋势较相似,5个方向都观测到了震前3—5天负异常稍高于正异常的现象.按震中±10°、±20°、±30°不同空间尺度分析震前0—15天TEC变化,研究表明临震电离层异常最明显的区域并不位于震中的正上空,而是向磁赤道方向偏移,空间影响尺度大约为±15°左右;正异常在震前14天、10天震中西南方向出现不同程度的高值区,负异常在震前5天震中东南方向较明显.最后,应用静电场假设对这些现象进行了解释.

英文摘要：

Abstract Using GPS TEC data, we have statistically analyzed the ionospheric perturbations prior to the Ms≥6. 0 earthquakes in China main land from November 1st, 1998 to December 31st, 2010. The obtained results indicated that the GPS TEC had the same variation trend above the epicenter and eastern, southern, western, northern directions 15 days before earthquakes, and decrease occurred in all the 5 directions from 3 days to 5 days. Through different space scale analysis of ±10°、±20°、±30°, it was found that the maximum seismoionospheric disturbance didnrt appear just above the epicenter, but shifted to the magnetic equator, and it was worth to point out that the affected region in ionosphere was about ＋ 15°. Besides this, prior to earthquakes, positive anomalies appeared in the southwestern direction before 14th, 10th days, and there were obviously negative anomalies in the southeastern direction before 5th day. At last, a hypothesis of electrostatic field channel in lithosphere-atmosphere-ionosphere coupling was used to explain the observed phenomena.