摘要:
本文利用RANSAC-PSO算法研究在反演断层滑动参数时所用大地测量数据包含粗差的问题.在模拟实验中对理论观测值加入1%、5%、10%粗差,分别采用粒子群算法、选权迭代算法和RANSAC PSO算法反演断层滑动参数.结果表明,当观测值中包含粗差率达10%时,PSO算法反演的滑动参数与理论值相差23.2 cm,选权迭代法反演的滑动参数与理论值相差26.2 cm,而RANSAC-PSO反演的滑动参数与理论值相差小于1 cm.芦山地震具有以逆冲为主兼具少量左旋走滑性质,采用芦山地震同震GPS位移数据分别以PSO算法和RANSAC-PSO算法反演断层滑动参数,RANSAC-PSO算法反演的走滑量为0.051 8 m,倾滑量为0.828 9 m,均大于PSO的反演结果;释放能量1.000 9×1019 N·m(Mw6.63),与GCMT的1.060 0×1019N·m更加吻合.分别用RANSAC-PSO算法与PSO算法反演的滑动参数计算地表水平位移,并与GPS观测进行对比,发现二者在计算距断层的远场点时,计算的水平位移基本一致;而在计算距断层的近场点时,RANSAC-PSO算法表现更为优秀,尤其体现在LS07点上,其计算值与GPS观测值完全重合.%The RANSAC-PSO algorithm is used to study the problem of gross errors ingeodetic data as a resultof fault slip parameters inversion.In the simulation experiment,1%,5% and 10% of the gross errors are added to the theoretical observations.Particle swarm optimization,selecting weight iteration and RANSAC-PSO algorithm are used to inverse the fault slip parameters.The results show that the difference from the theoretical value is 23.2 cm by the PSO,it is 26.2 cm by the selecting weight iteration,however,it is less than lcm by RANSAC-PSO,when the gross error rate is 10%.The characteristics of Lushan earthquake are thrust-dominated with a small amount of left-lateral strike-slip.In this paper,the PSO algorithm and RANSAC-PSO algorithm are used to calculate the fault slip parameters,respectively,with the coseismal GPS displacement data.The strike-slip is 0.0518 m and dip-slip is 0.8289 m by RANSAC-PSO algorithm,which are greater than the results of PSO.In addition,the energy released is 1.000 9× 1019 N·m(Mw6.63),which is consistent with GCMT 1.060 0× 1019 N·m.The horizontal displacements of the ground surface are recalculated with the sliding parameters that invert by the RANSAC-PSO algorithm and the PSO algorithm,respectively.The results show that the calculated horizontal displacements and GPS observations are basically the same as when the points are far away from the fault,the RANSAC PSO algorithm performs better than PSO when the calculating points are near the fault.The calculated value of LS07 completely coincides with GPS observations.