SUMMARY

A collection of earthquake sources recorded at a single station, under specific conditions, are considered as a source array (SA), that is interpreted as if earthquake sources originate at the station location and are recorded at the source location. Then, array processing methods, that is array beamforming, are applicable to analyse the recorded signals. A possible application is to use source array multiple event techniques to locate and characterize near-source scatterers and structural interfaces. In this work the aim is to facilitate the use of earthquake source arrays by presenting an automatic search algorithm to configure the source array elements. We developed a procedure to search for an optimal source array element distribution given an earthquake catalogue including accurate origin time and hypocentre locations. The objective function of the optimization process can be flexibly defined for each application to ensure the prerequisites (criteria) of making a source array. We formulated four quantitative criteria as subfunctions and used the weighted sum technique to combine them in one single scalar function. The criteria are: (1) to control the accuracy of the slowness vector estimation using the time domain beamforming method, (2) to measure the waveform coherency of the array elements, (3) to select events with lower location error and (4) to select traces with high energy of specific phases, that is, sp- or ps-phases. The proposed procedure is verified using synthetic data as well as real examples for the Vogtland region in Northwest Bohemia. We discussed the possible application of the optimized source arrays to identify the location of scatterers in the velocity model by presenting a synthetic test and an example using real waveforms.

中文翻译：

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地震震源阵列：地壳结构研究中的最佳配置和应用

概要

在特定条件下，在单个站点上记录的地震震源集合被视为震源阵列（SA），它被解释为好像震源起源于站点位置并记录在震源位置。然后，阵列处理方法，即阵列波束成形，可用于分析记录的信号。一种可能的应用是使用源阵列多事件技术来定位和表征近源散射体和结构界面。在这项工作中，目的是通过提出一种自动搜索算法来配置震源阵列单元，以促进地震震源阵列的使用。我们给定了地震目录，包括准确的起震时间和震中位置，开发了一种搜索最佳震源阵列元素分布的程序。可以为每个应用程序灵活定义优化过程的目标函数，以确保制作源数组的先决条件（标准）。我们将四个定量标准制定为子函数，并使用加权和技术将它们组合为一个标量函数。标准是：（1）使用时域波束成形方法控制慢度矢量估计的精度；（2）测量阵列元素的波形相干性；（3）选择位置误差较小的事件；（4）选择具有特定相位高能量的迹线，即sp相或ps相。使用合成数据以及西北波西米亚州Vogtland地区的实际示例，对所建议的程序进行了验证。