ERROR ANALYSIS OF STRAIN RATES RESULTED FROM ERRORS OF GPS MEASUREMENT
由ＧＰＳ站点速度观测误差引起的应变率计算结果的误差分析

Using the Kriging method to interpolate the spatially irregular scattered GPS velocity data to uniform grid values,and then calculate the strain rate for each volume element,thus the strain rate fields of China continent and adjacent areas have obtained.Futhermore,a larger number of independent calculations of strain rates are repeated from GPS vectors with measurement errors,and the components of mean strain rates,as well as the errors,are obtained statistically by Monte Carlo technique.The results show that the magnitudes of the strain rates in the west of the China continent are 3-5 times greater than those in the east China.The orientations of principal strain rates are in good agreement with those of P-axis and T-axis of focal mechanisms.The distribution of maximum shear strain rate delineates some major active fault zones surrounding the Tibetan plateau.The tensile strain rates in the interior of the Tibet are consistent with the extensional tectonics.Also the analysis of the strain rate errors suggests that the errors of the strain rates computed from GPS measurements are mainly originated from the errors of GPS data.The accuracy of GPS survey does not meet the requirements for precisely computing the strain rates in the region where,for example,in the east China the deformation is small.