基于现代大地测量手段的青藏高原南缘地壳形变分析

Analysis of Crustal Deformation in the Southern Margin of the Qinghai-Tibet Plateau Based on Modern Geodetic Techniques

基于2003~2013年GRACE卫星重力、GPS和绝对重力数据对青藏高原南缘地壳形变进行探讨分析。结果表明,拉萨测站1999~2015年垂向隆升速率为1.5 mm/a,显示出拉萨测站持续隆升的特点。结合南加州综合网络构建的远程连续GPS参考站,另外选择TPLJ、CHLM、JMSM测站数据进行分析。GPS结果表明,4个测站2003~2013年平均隆升速率为2.3±0.11 mm/a, GRACE垂向位移时间序列显示4个测站2003~2013年除季节性变化外也具有轻微上升趋势,平均速率为0.35 mm/a。联合绝对重力资料在考虑诸多因素(地壳隆升、侵蚀、GIA等)后得到拉萨测站近年重力变化约为-0.97μGal/a,青藏高原拉萨测站地下地壳底部增厚速率约为4.4 cm/a,揭示了青藏高原南部地区的地壳形变特征——地壳隆升与底部增厚。

Based on the gravity recovery and climate experiment(GRACE), GPS and absolute gravity data from 2003 to 2013, we discuss and analyze the crustal deformation in the southern margin of the Qinghai-Tibet plateau. The result shows the LHAZ station rising at a rate of 1.5 mm/a from 1999 to 2015, which indicates that the LHAZ station has always been uplifting. We analyze the vertical time series of four stations(LHAZ, TPLJ, CHLM, JMSM) of the remote continuous GPS station package(RCGSP) constructed by southern California integrated GPS network(SCIGN). The GPS results show that the four stations have an average uplifting rate of 2.3±0.11 mm/a from 2003 to 2013. Meanwhile, the vertical displacement time series indicates that the four stations have a slight upward trend from 2003 to 2013, with an average rate of 0.35 mm/a. Combined with absolute gravity data, considering many factors(crustal uplift, erosion, GIA), the gravity variation of LHAZ station in recent years is about-0.97 μGal/a and the rate of crustal bottom thickening at LHAZ station is about 4.4 cm/a, which reveals the characteristics of crustal deformation in the southern margin of the Qinghai-Tibet plateau: crustal uplift and bottom thickening.