印尼8.7级大震前后GPS观测站的地壳水平与垂直位移时间序列结果

利用IGS及中国地壳运动观测网络GPS连续观测站6年多时间的观测结果, 以中国大陆东部的稳定点组作为水平位移与垂直位移解的参考基准, 得到了2004年12月26日印尼苏门答腊8.7级与2005年3月28日8.5级大震前后GPS观测站的地壳水平及垂直位移时间序列的结果。 尽管所采用的GPS站点少, 且分布范围大, 但仍可看到在如此大的地震震前、 同震与震后地壳运动的特征, 为今后观测研究提供了十分有意义的结果。 文中所采用稳定点组基准有效消除水平位移场的平移与旋转, 而局部椭球面的不平性对计算区域地壳运动结果, 特别是对垂直位移的影响很小, 说明了位移解所描述的大范围区域位移场是合理的。 这两次地震的同震水平位移及震后的垂直位移影响量级达数厘米, 范围达远离8.7级地震震中4500 km之外, 甚至更远。

Results of time series of horizontal and vertical displacements at GPS observation stations before and after the Sumatra Earthquake with 8. 7 in Indonesia

Time series of horizontal and vertical displacements at GPS Observation Stations of IGS and the Crustal Movement Network of China(CMONOC) before and after the Sumatra Earthquake with M8.7 on Dec.26,2004 and earthquake with M8.5 on March 28,2005 in Indonesia are obtained from the data of continuous GPS observation for more than 6 years with datum definition of a group of stable stations of small mutual horizontal or vertical displacements for the time series.Though the number of GPS observation stations is small and they scatter in a vast area,the characteristics of the pre-seismic,co-seismic and post-seismic crustal movements for such huge earthquakes can be seen and the results are meaningful for further studies.The datum definition used in the paper effectively reduced the translation and rotation in the horizontal displacement field and the influence of the non-parallelism of the local ellipsoidal surface on vertical displacements is small during the time period covered in this study.They indicate that the displacement field in vast area obtained by the displacement solutions in the paper is reasonable.The co-seismic horizontal displacements and the postseismic vertical displacement are as large as a few centimeters and are detected 4500 km away from the epicenter of M8.7 earthquake or even farther.