摘要
高频射线声学认为声信号传播时间变化取决于连接声源和接收器的本征声线上的声速变化,然而地震层析中指出低频下的声传播时间与本征声线周围的声速变化有关,且可以用传播时间敏感核来量化传播时间扰动和声速扰动的关系。本文基于Skarsoulis传播时间敏感核的推导,通过两个数值算例分析了传播时间敏感核的几何结构,验证了本征声线周围的声速变化会影响低频下的声信号的传播时间。
Arrival times in ray theory is modeled as travel times along eigenrays connecting the source and receiver, and their variations are associated with variations of the sound speed along the geometric ray paths. However, it has been pointed out that low-frequency travel times are sensitive to sound-speed changes in areas surrounding the eigenrays, and the 3-D spatial distribution of sensitivity of travel-time to sound-speed perturbations can be represented by the travel-time sensitivity kernel(TSK). In this paper, the TSK derivation given by Skarsoulis is reviewed and two TSK examples are shown to analyze the geometric structure of the TSK, which verifies that the sound-speed changes surrounding the eigenrays will affect the low-frequency arrival times.
引文
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