利用改进的粒子群算法反演视震源时间函数
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摘要
视震源时间函数的提取是研究震源参数的重要途径.本文提出了利用改进的粒子群(PSO)算法反演视震源时间函数的方法,以水平线方法得到的结果作为PSO算法的初值,并对PSO算法的惯性因子和学习因子进行改进,提高计算效率.采用改进的PSO算法对模拟数据进行了反演计算,并与映射Landweber反褶积(PLD)方法和遗传算法(GA)进行了对比分析.结果表明,相对于PLD方法,改进的PSO算法反演结果与真实结果误差更小;相对于遗传算法,改进的PSO算法计算效率提高了5倍以上.最后,利用改进的算法对2005年10月8日巴基斯坦克什米尔MW7.6地震的P波视震源时间函数进行了提取,结果表明此次地震P波视震源时间函数在25s之内,震源沿西北向破裂.该结果与张勇等的结果一致.
Retrieving apparent source time function (ASTF) is an important way to study earthquake source parameters. This paper proposes an improved particle swarm optimization (PSO) algorithm for retrieving ASTF. The result from water-level method is used as the initial global best value of PSO, and the inertia factor and learning factor of PSO are modified to increase computing efficiency. The results of simulation experiments using the improved PSO method are compared with those by using projected Landweber deconvolution (PLD) and generic algorithm (GA). The comparison shows that the inversion result by using improved PSO has smaller residuals relative to that by using PLD, and the improved PSO has increased computation efficiency by more than 500% relative to GA. Finally, the improved PSO method is used to retrieve P-wave ASTFs of the 8 October 2005 Kashmir MW7.6 earthquake. The results show that the duration of P-wave ASTF of the earthquake is within 25 s, and the rupture extends in northwest direction, which are consistent with those by Zhang et al.
Retrieving apparent source time function (ASTF) is an important way to study earthquake source parameters. This paper proposes an improved particle swarm optimization (PSO) algorithm for retrieving ASTF. The result from water-level method is used as the initial global best value of PSO, and the inertia factor and learning factor of PSO are modified to increase computing efficiency. The results of simulation experiments using the improved PSO method are compared with those by using projected Landweber deconvolution (PLD) and generic algorithm (GA). The comparison shows that the inversion result by using improved PSO has smaller residuals relative to that by using PLD, and the improved PSO has increased computation efficiency by more than 500% relative to GA. Finally, the improved PSO method is used to retrieve P-wave ASTFs of the 8 October 2005 Kashmir MW7.6 earthquake. The results show that the duration of P-wave ASTF of the earthquake is within 25 s, and the rupture extends in northwest direction, which are consistent with those by Zhang et al.
引文
许力生,陈运泰.2002.震源时间函数与震源破裂过程[J].地震地磁观测与研究,23(6):1--7.
许力生,陈运泰.2004.从全球长周期波形资料反演2001年11月14日昆仑山口地震时空破裂过程[J].中国科学:D辑,34(3):256--264.
张勇.2008.震源破裂过程反演方法研究[D].北京:北京大学地球物理学系:1--70.
张勇,许力生,陈运泰.2009.提取视震源时间函数的PLD方法及其对2005年克什米尔MW7.6地震的应用[J].地球物理学报,52(3):672--680.
Bertero M,Bindi D,Boccacci P,Cattaneo M,Eva C,Lanza V.1997.Application of the projected Landweber method tothe estimation of the source time function in seismology[J].Inverse Probl,13(2):465--486.
Kennedy J,Eberhart R.1995.Particle swarm optimization[C]∥Proceedings of IEEE International Conference onNeural Networks,4:1942--1948.
Kraeva N.2004.Tikhonov’s regularization for deconvolution in the empirical Green function method and verticaldirectivity effect[J].Tectonophysics,383(1):29--44.
Mori J,Hartzell S H.1990.Source pulse enhancement by deconvolution of an empirical Green’s function[J].GeophysRes Lett,12(1):33--36.
Poli R,Kennedy J,Blackwell T.2007.Particle swarm optimization[J].Swarm Intell,1(1):33--57.
Radulian M,Popa M.1996.Scaling of source parameters for Vrancea(Romania)intermediate depth earthquake[J].Tectonophysics,261(1):67--81.
许力生,陈运泰.2004.从全球长周期波形资料反演2001年11月14日昆仑山口地震时空破裂过程[J].中国科学:D辑,34(3):256--264.
张勇.2008.震源破裂过程反演方法研究[D].北京:北京大学地球物理学系:1--70.
张勇,许力生,陈运泰.2009.提取视震源时间函数的PLD方法及其对2005年克什米尔MW7.6地震的应用[J].地球物理学报,52(3):672--680.
Bertero M,Bindi D,Boccacci P,Cattaneo M,Eva C,Lanza V.1997.Application of the projected Landweber method tothe estimation of the source time function in seismology[J].Inverse Probl,13(2):465--486.
Kennedy J,Eberhart R.1995.Particle swarm optimization[C]∥Proceedings of IEEE International Conference onNeural Networks,4:1942--1948.
Kraeva N.2004.Tikhonov’s regularization for deconvolution in the empirical Green function method and verticaldirectivity effect[J].Tectonophysics,383(1):29--44.
Mori J,Hartzell S H.1990.Source pulse enhancement by deconvolution of an empirical Green’s function[J].GeophysRes Lett,12(1):33--36.
Poli R,Kennedy J,Blackwell T.2007.Particle swarm optimization[J].Swarm Intell,1(1):33--57.
Radulian M,Popa M.1996.Scaling of source parameters for Vrancea(Romania)intermediate depth earthquake[J].Tectonophysics,261(1):67--81.
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