一种地方与区域地震震源机制反演技术:广义极性振幅技术(一)——原理与数值实验

An inversion technique for the mechanisms of local and regional earthquakes:generalized polarity and amplitude technique(Ⅰ)——Principle and numerical tests

基于数十年来已有的研究进展,提出了一种地方和区域地震震源机制反演技术——广义极性振幅技术(GPAT),并通过一系列数值实验检验了这种技术的可行性和抗干扰能力.首先,从地震波场概念出发,利用P波初动极性与广义震相振幅构建矢量,建立反演系统,并给出求解技术;然后,考虑影响反演结果的各种因素,包括台站布局、台站数目、随机噪声、震中位置误差、震源深度误差和速度模型误差,分别进行了单一因素影响测试;最后,同时考虑各种因素进行了综合测试.实验结果表明,GPAT是可行的,具有良好的抗干扰能力.需要强调的是,在众多影响因素中,速度模型误差对反演结果的影响最大.

An inversion technique for focal mechanisms of local and regional earthquakes, named Generalized Polarity and Amplitude Technique （GPAT）, is proposed based on the progress already made over decades, and its feasibility and capability of resisting disturbance are tested by a series of numerical experiments. At first, an inversion equation system is constructed with the vectors consisting of the polarities of the P first motion and the maximal amplitudes of generalized phases based on the concept of wave field, and a technique for solving the equation system is specified. Then, a series of experiments are conducted for the effect of various factors on inversion results, including distribution of observation stations, number of the stations, random noises, errors in epicenter location, errors in focal depth and errors in velocity model. Finally, a special experiment is designed for comprehensive effect of all the factors. The experiments suggest that the GPAT is feasible, and has rather good capability of resisting disturbance. It must be stressed that the error in velocity model has the strongest effect on inversion resultcompared with other factors.