地震转换波测深中二次反射波震相的识别和利用

二次反射波震相的识别和利用对于进一步发展地震转换波测深法有重要意义。本文利用合成地震图方法,分析研究了短周期远震三分量初始30秒记录中主要震相的运动学和动力学特征。文中集中分析了PPP和PPS型二次波震相的振幅、波形和到时差等特征,及其与震中距、界面两侧波速差、界面结构和介质吸收等因素的关系。讨论了综合利用PS波和二次波震相的到时差资料测定介质速度参数的方法,并介绍了应用实例。

Recognition and Application of Twice-Reflected Phases in Method of PS Converted Waves of Earthquakes

Recognition and application of twice-reflected phases is a significant problem in the method of PS converted waves of earthquakes. In this paper, we have made some study and analysis of kinematic and dynamic characteristics of major phases in the beginning 30-second part of 3-component, short-period record of a distant earthquake by method of synthetic seismograms. The main attention was concentrated to analysis of amplitude, waveform and arrival time delay of PPP and PPS twice-reflected phases, and to analysis of their relations with epicentre distance, velocity contrast on both sides of boundary, structures of the boundary and absorption of the medium. The problem of possible way of complex using the arrival-time delay of PS and PPP twice-reflected phases for determination of velocity parameters was discussed, and a practical example of application of PPP twice-reflected waves was also introduced.