A Random Model for Half-Amplitude Decay Times of Rayleigh Waves Extended Array Evaluation Program

摘要

An approach to prediction of long-period Rayleigh wave signal persistence is taken through 'mean-time-between-failure' and 'waiting time' stochastic models. The estimate applies only to the generalized case of a network of recording stations and wide spatial distribution of earthquake sources. Rayleigh waves from Eurasian earthquakes reocrded on Very Long Period Experiment systems were analyzed to obtain data for the study. Successive time intervals between the maximum recorded amplitude, A , and the latest point of recorded signal equal to A/2, the time between A/2 and A/4, A/4 and A/8, and etc. were measured until the signal amplitude reached tha ambient noise level. Resulting 'half-amplitude decay times' (Wn) were found to follow a gamma probability law. The distribution of observed Wn fits this law with 0.90 confidence or greater according to the Chi-squared criterion. The results indicate that the probability distribution of half-amplitude decay times in earthquake Rayleigh waves can be readily estimated using appropriate gamma distribution parameters. (Author)