川滇地区地壳应变场的GPS与地震矩张量联合反演研究

Current Crustal Strain Field in the Sichuan-Yunnan Area by Joint Inversion of GPS and Seismic Moment Tensor

利用川滇地区1903～2003年间的84个地震矩张量和1998～2004年间214个GPS站速度观测值，采用方差分量估计方法确定联合反演中地震矩张量与GPS站速度值之间的权比例因子，计算分析了川滇地区的地壳应变场。结果表明：①采用方差分量估计确定联合反演中权比例因子的方法，得到的GPS站速度观测值的权比例因子为0．833，较地震矩张量的权比例因子0.167大，充分体现出分布相对合理的高精度GPS观测值在反演中的重要性；②川滇地区的应变场大致表现出如下的特征：主应变方向在30°N以北的区域为东西向；30°N以南、100°E以西的区域为北东向；30°N以南、100°E以东的区域为北西向。

By using 84 seismic moment tensors, collected from the Harvard centroid moment tensor between 1903 and 2003, and 214 GPS velocity observations, collected from the crustal motion observation network of China between 1998 and 2004, we fix the weight scaling factor of these two kinds of data in the joint inversion through Helmert method of variance components estimation （VCE）, and invert for current crustal motion in Sichuan-Yunnan area. Meanwhile, on the basis of the analysis of inverted results, the following views are concluded. （1） By using VCE, the weight scaling factor of GPS observations with a value of 0. 833 is higher than that of seismic data, with a value of 0. 167. It shows the importance of GPS observations with high accuracy and relatively uniform distribution in joint inversion. （2）The crustal strain field in Sichuan-Yunnan area shows that the direction of compression strain is EW in the areas above 30°N and below 30°N, NE in the west of 100°E, and NW in the east of 100°E, which is accordance with other studies.