中文摘要：

全球定位系统（GPS）观测可提供高精度、大范围和准实时的地壳运动定量数据，使得在短时间内获取大范围地壳运动速度场成为可能，已广泛地用于监测现今地壳运动。该文利用1993～2002年间5期GPS观测资料采用自洽统一参考框架方法分析研究了青藏高原地区的现今地壳运动，获得了GPS速度场和应变场，结果及其精度较以前有所改善，尤其在垂直速度和喀喇昆仑嘉黎以南地区应变参数较以前结果有较大不同。通过分析与比较得出：目前喜玛拉雅块体以N37．1±0．7°E的挤压为主，达到了-98．5±4．2×10^-9／a，同时兼有的N127．1±0．7°E方向拉张，达到了26．7±2．8×10^-9／a，最大剪应变62．6±2．6×10^-9／a，面应变-78．1±5．1×10^-9／a，这与前期的研究成果有着较大的不同；西藏块体N39．0±2．0°E挤压为主，达到了-20．3±1．2×10^-9／a，同时兼有N129．0±2．0°E的拉张，达到了10．8±1．6×10^-9／a，最大剪应变15．6±1．0×10^-9／a，面应变9．5±2．2×10^9／a；总体而言，喜马拉雅块体到西藏块体的主压应变率和拉张应变率变小；青藏高原现今东西向拉张主要体现在西藏块体中部；此外，GPS结果显示青藏高原每年以3～5mm的速率处于隆升中，这一结果与前期GPS成果相差约2～3mm

英文摘要：

GPS has been widely applied to monitor crustal motion, and could provide high precision, wide range and quasi real time measurement, which makes it possible to obtain crustal velocity field in a relative short pe riod. Since 1993, GPS was used to monitor the movement in the Tibetan Plateau. We have analyzed all campaigns and continuous GPS data collected in the Tibetan Plateau from 1993 to 2002, using GAMIT/GLOBK software. We determine the stations position and velocity vectors in a single, self-consistent reference frame, whereas previous studies used different frames for different surveys and used different fidueial stations for different period surveys. This helps mitigate the effects of changes in the network geometry as a function of time. In the paper, we give GPS velocity field and strain field, the results and precision are better than previous esti mates, especially in vertical velocity field and the strain rate parameters of subregion south of Karakorum-Jiali fault. The results show the Himalayan block is mainly under compressing strain, and the maximum compressing rate is -98.5±4.2× 10^-9/a and with the extension rate of 26.7±2.8× 10^-9/a in the direction of N127.1 ±0.7°E. Its maximum shearing strain reaches up to 62.6 ± 2.6 × 10^-9/a, and areal dilatation up to -78.1 ± 5.1 × 10^-9/a. The middle part of the Tibet block is mainly under compressing strain, and the maximum compressing rate is -20.3±1.2×10^-9/ainthe direction of N39.0±2.0°Eand with the extension rate of 10. 8±1. 6×10^-9/a in the direction of N129±2.0°E. Its maximum shearing strain reaches up to 15.6±1.0×10^-9/a, and arealdila tation up to -9.5±2.2× 10^-9/a. Both principal compressing strain rate and extension rate trail off from the Himalayan block to the middle part of the Tibet block. Besides, GPS result shows that the Tibetan Plateau up lifts with 3-5 mm/a, which is 2-3 mm less than the previous estimates.