An improved MCMC algorithm for inversion of source parameters using GPS data under the Bayesian framework
With the rapid development of machine hardware and software facilities,the Bayesian algorithm has been widely used in various fields.In the Bayesian framework,the convergence of the Markov chain is very important for obtaining reasonable and correct source parameters when the sampling MCMC method is used to solve the source parameter problem.Based on existing research,this paper improves the random step generation method of the MCMC method,so that the random step size conforms to the normal distribution as a whole.Considering that the initial value is also crucial to the convergence of the Markov chain,a nonlinear heuristic search algorithm combined with the MCMC algorithm under the Bayesian framework is proposed to jointly invert the seismic source parameters.The MPSO algorithm is used to provide the initial value,and a set of randomly generated values is used as a control.Under the Meinong earthquake,the GPS displacement data verify that the improved MCMC algorithm is superior to the original algorithm in terms of convergence speed,and the confidence interval is more reasonable.At the same time,it is verified that the MPSO provides the initial value for the Bayesian algorithm,which not only overcomes the instability of the heuristic search algorithm but also improves the convergence speed of the improved algorithm.In order to verify that the improved algorithm can greatly reduce the number of times required for sampling and expand the application of the improved algorithm in different types of earthquakes,this paper inverts the source parameters of the Bodrum-Kos Mw6.6 dip-slip earthquake with 100000 times of sampling.The inversion results support that the Bodrum-Kos seismic fault is a north-dipping fault.The root mean square error of the deformation field fitting in the east-west direction(EW)is 1.43 mm,the root mean square error in the north-south direction(SN)is 3.23 mm,and the root mean square error in the vertical direction is 9.69 mm,which is better than most of the existing literature of the same type.
Bayesian frameworkMCMC algorithmInversion of source parametersThe Meinong earthquakeThe Bodrum-Kos earthquake
万方数据
维普
