汶川地震同震电离层扰动研究

利用中国大陆陆态观测网(CMONOC)的下关、 昆明和庐州GPS台站, 对汶川地震引起的同震电离层扰动(CID)进行研究。 通过对GPS原始观测数据进行处理证实汶川地震存在5个明显的同震电离层扰动(CID)现象。 根据GPS TEC时间序列和走时, 得到在电离层高度CID的水平传播速度为1.1 km/s, 属于震中区地表抬升引起的声波在电离层中传播速度; 同时, 也得到次一级CID传播速度接近0.7 km/s, 认为可能是重力波。 在此基础上, 利用射线追踪模型寻找震中位置发现, 当CID水平传播速度为1000 m/s时, 发震时刻对应的标准偏差能达到最小值19.55 s, 相应的CID起源位置是30.8°N, 103.15°E, 距离实际震中西南方向33.6 km。

Coseismic Ionosphere Disturbances of the 2008 Wenchuan Earthquake

We use three ground GPS receiver stations at Xiaguan, Kunming and Luzhou in the CMONOC to study coseismic ionospheric disturbance (CID) for the 2008 Wenchuan earthquake. We retrieve high precise slant total electron content (STEC) through removing the DCB (Difference Code Bias) effect in the line of sight of GPS. Through preproccess of the GPS data and the STEC, we obtained the DTEC time series and the TEC traveling time plots among them. The results show that there exists two CID horizontal propagation speeds in this research. The first is the acoustic speed in the height of ionosphere, about 1.1 km/s, and the second is the secondary CID speed closed to 0.7 km/s, considered to belong to the gravity wave. Finally, using the ray-tracing technique, when the CID speed equals to the 1000 m/s, the standard deviation of the earthquake onset time can reach the minimum value 19.55s, and the origin of the CID is located at 30.8°N,103.15°E which is about 33.6 km southwest of the Wenchuan earthquake epicenter.