Determinaion of the Direction of the Ground Noise Source

众所周知，微震动是由各种噪声源诱发的三维地面振动，分析微震动在三维空间中的轨道对探讨微震动的特征和机理具有重要意义。本文提出了一种分析三维振动轨道的新方法——三维旋转谱，并讨论了该方法在微震动分析中的适用性。首先，介绍了三维旋转谱的理论，描述了三维旋转谱的实验步骤和数值格式。其次，对位于Yatsushiro平面和位于地面热区的两个测点进行了微震的现场测量，并根据所提出的方案分析了每个测点的微震特征。明确了微震动可分为瑞利波型和洛夫波型两种振动类型，并通过振动面分析确定了产生微震动的震源方向。结果表明，三维旋转谱可以用于分析微颤地震动的特征及其机理。

It is well known that the micro-tremor is the three dimensional ground vibration induced by the various noise sources and the analysis of orbit of the vib ation in three dimensional space is important for discussing the characteristics and mechanism of the micro-tremor.In this project, a new technique for analyzing the orbit of the three dimensional vibration, namely three dimensional rotary spectrum, is presented and the applicability of it to the micro-tremor is discussed.Firstly, the theory of the three dimensional rotary spectrum is presented and experimental procedures and numerical scheme of it are described.secondly, field measurements of the micro-tremor were carried out at two sites, one is located in Yatsushiro plane and the other is located in the ground thermal region, and the characteristics of the miocro-tremor of each sites are analyzed by the proposed scheme. It is made clear that the micro-tremor can classified into two types of vibration, Rayleigh wave type and Love wave type, and the direction of the source which generate the tremor is determined from the analysis of the vibration plane.It is concluded that the three dimensional rotary spectrum has a promise to analyze the characteristics of the ground vibration of micro-tremor as well as the mechanism of it.