Abstract The observation of infrasound signals in the vicinity of volcanoes is a powerful tool to understand the source of explosive volcanic activity. Although the propagation of infrasound signals is affected by the local topography, such effects are often ignored in the analysis, leading to potential misinterpretation of the source parameters. In this study, we propose a simple low-cost method of evaluating the attenuation of infrasound signals by topographical barriers. In this method, the first step approximates the elevation profile between the source and station into one thin screen-like barrier. Then, a mathematically exact solution of a sound diffraction problem is adopted to evaluate the attenuation of the infrasound amplitudes. To assess the validity of this method, the obtained estimates are compared with actual infrasound data observed at Sakurajima volcano, Japan. The results show that the estimates of relative amplitude to a reference station are more accurate than those considering only geometrical spreading, suggesting that the proposed method provides a useful first-order investigation of the attenuation of infrasound signals. The spatial distribution of the attenuation in the entire area of the volcano was also estimated, revealing a significant contrast between the eastern and western sides of the study area. Variations in signal attenuation also depend on the radial distance from the crater and were mainly attributed to variations of the relative screen height to the incident wavelength.

中文翻译：

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利用薄屏声衍射解决方案评估火山地形周围衰减的次声波

摘要 火山附近的次声信号观测是了解火山爆发活动来源的有力工具。尽管次声信号的传播受局部地形的影响，但在分析中往往忽略这种影响，从而导致对源参数的潜在误解。在这项研究中，我们提出了一种简单的低成本方法来评估地形障碍对次声信号的衰减。在这种方法中，第一步将源和站之间的高程剖面近似为一个薄的屏幕状屏障。然后，采用声音衍射问题的数学精确解来评估次声振幅的衰减。为了评估这种方法的有效性，将获得的估计与在日本樱岛火山观测到的实际次声数据进行比较。结果表明，相对于参考站的相对幅度估计比仅考虑几何扩展的估计更准确，这表明所提出的方法提供了有用的次声信号衰减的一阶调查。还估计了火山整个区域的衰减空间分布，揭示了研究区东侧和西侧之间的显着对比。信号衰减的变化还取决于距陨石坑的径向距离，主要归因于相对屏幕高度与入射波长的变化。结果表明，相对于参考站的相对幅度估计比仅考虑几何扩展的估计更准确，这表明所提出的方法提供了有用的次声信号衰减的一阶调查。还估计了火山整个区域的衰减空间分布，揭示了研究区东侧和西侧之间的显着对比。信号衰减的变化还取决于距陨石坑的径向距离，主要归因于相对屏幕高度与入射波长的变化。结果表明，相对于参考站的相对幅度估计比仅考虑几何扩展的估计更准确，这表明所提出的方法提供了有用的次声信号衰减的一阶调查。还估计了火山整个区域的衰减空间分布，揭示了研究区东侧和西侧之间的显着对比。信号衰减的变化还取决于距陨石坑的径向距离，主要归因于相对屏幕高度与入射波长的变化。还估计了火山整个区域的衰减空间分布，揭示了研究区东侧和西侧之间的显着对比。信号衰减的变化还取决于距陨石坑的径向距离，主要归因于相对屏幕高度与入射波长的变化。还估计了火山整个区域的衰减空间分布，揭示了研究区东侧和西侧之间的显着对比。信号衰减的变化还取决于距陨石坑的径向距离，主要归因于相对屏幕高度与入射波长的变化。