Abstract In volcanic environments, the correct interpretation of the signals recorded by a seismic station is critical for a determination of the internal state of the volcano. Those signals contain information about both the seismic source and the properties of the path travelled by the seismic wave. Therefore, understanding the path effect is necessary for both source inversions and geophysical investigation of the volcanoes' properties at depth. We present an application of the seismic adjoint methodology and sensitivity kernel analysis to investigate seismic wave propagation effects in the upper volcanic edifice. We do this by performing systematic numerical simulations to calculate synthetic seismograms in two-dimensional models of Mount Etna, Italy, considering different wave velocity properties. We investigate the relationship between different portions of a seismogram and different parts of the structural volcano model. In particular, we examine the influence of known near-surface low-velocity volcanic structure on the recorded seismic signals. Results improve our ability to understand path effects highlighting the importance of the shallowest velocity structure in shaping the recorded seismograms and support recent studies that show that, although long-period seismic events are commonly associated with magma movements in resonant conduits, these events can be reproduced without the presence of fluids. We conclude that edifice heterogeneities impart key signatures on volcano seismic traces that must be considered when investigating volcano seismic sources.

中文翻译：

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使用敏感性核量化上火山结构的强地震传播效应

摘要 在火山环境中，正确解释地震台记录的信号对于确定火山内部状态至关重要。这些信号包含有关震源和地震波传播路径特性的信息。因此，了解路径效应对于源反演和深度火山性质的地球物理研究都是必要的。我们提出了地震伴随方法和灵敏度核分析的应用，以研究上火山结构中的地震波传播效应。我们通过执行系统的数值模拟来计算意大利埃特纳火山二维模型中的合成地震图，并考虑到不同的波速特性。我们研究了地震图不同部分与构造火山模型不同部分之间的关​​系。特别是，我们检查了已知的近地表低速火山结构对记录的地震信号的影响。结果提高了我们理解路径效应的能力，突出了最浅速度结构在形成记录的地震图方面的重要性，并支持最近的研究表明，虽然长周期地震事件通常与共振管道中的岩浆运动有关，但这些事件可以重现在没有流体的情况下。我们得出结论，建筑物的异质性赋予火山地震轨迹的关键特征，在调查火山地震源时必须考虑这些特征。