中文摘要：

利用南海及其周围地区的GPS数据,分析南海及周围地区速度场和应变场的空间变化,以及相邻块体之间的相对运动。研究发现,南海现今仍在继续扩张,西部是从其北边缘向南沿NW-SE方向逐渐扩张的,东部是从中心向北与向南逐渐扩张的。由主张应变率计算的中央海盆近SN方向的平均扩张速率为3.1 mm/a。在南海东部（117.0°E）,南北之间（11°～22°N）SN方向的扩张速率为9.3 mm/a,小于65M a以来NNW-SSE方向13.0 mm/a的平均扩张速率。南海的扩张运动是印度板块、太平洋和菲律宾海板块与欧亚板块之间的相互作用,以及南海地区地幔物质上涌共同作用的结果。

英文摘要：

We collected and processed the site velocities of South China Sea（SCS） and its surrounding areas and obtained unified velocity field in ITRF2005.By analyzing the spatial variation of the velocity field and strain field,and relative motions between blocks it is discovered that the SCS extends still up to now.The western part of SCS is opening gradually NW-SE from its northern margin to south,but the eastern part of SCS is opening gradually from its central part to north and to south.On the basis of computed results of strain field,the average extension rate in about SN is 3.1 mm/a in the CSB and extension rate in SN is 9.3 mm/a in eastern part of SCS 117°E between 11°N and 22°N which is smaller than the average extension rate of 13.0 mm/a along NNW-SSE since 65 Ma.The expansive motion of the SCS is resulted from the common effects between Indian plate,Pacific plate,Philippine Sea plate and Eurasian plates,and the upwelling of the mantle matters of SCS area.