Investigating heterogeneous structures beneath active volcanoes is important for better understanding of volcanic activity and improved mitigation of volcanic risk. In central Japan, Hakone volcano has recently shown shallow earthquake swarms and deep low‐frequency earthquakes (DLFEs), which are probably related to geothermal or deep magmatic activity. In order to image the feeding system beneath this volcano, we estimate 3‐D P wave attenuation structure using waveform data recorded at permanent and densely distributed temporary seismograph stations. We first determine corner frequencies of the earthquakes and then perform a joint inversion to obtain attenuation terms (t*) and site responses. Values of t* are finally inverted to estimate the attenuation structure to a depth of 50 km. High‐attenuation zones at depths ≤5 km suggest that fracture zones are permeated with hydrothermal fluids. A high–strain rate zone revealed by geodetic observations is spatially correlated with a high‐attenuation volume at depths of 5–10 km, suggesting that the anelastic deformation is dominant in the high‐attenuation zones. A subvertical volume of moderate attenuation that is imaged at depths of 10–20 km beneath Hakone volcano is connected to the top of a zone of partial melting beneath Mt. Fuji at depths ≥30 km through a subhorizontal channel at a depth of ~25 km. DLFEs in the lower crust and fluid‐related activity such as earthquake swarms in the upper crust occur in this volume. The zone is thus interpreted as a fluid‐bearing pathway, which allows the rise of magmatic fluids to Hakone volcano.

中文翻译：

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日本中部箱根火山注入流体系统的地震约束

研究活动火山下面的非均质结构对于更好地了解火山活动和改善缓解火山风险具有重要意义。在日本中部，箱根火山最近显示出浅层地震群和深层低频地震（DLFE），这可能与地热或深部岩浆活动有关。为了图像此火山下方的送料系统，我们估计3- d P利用记录在永久和密集分布临时地震站波形数据波衰减结构。我们首先确定地震的转折频率，然后执行联合反演以获得衰减项（t *）和场地响应。t的值最后将*倒置，以估计50 km深度的衰减结构。深度≤5km的高衰减带表明裂缝带充满了热液。大地测量观测揭示的高应变率带在空间上与5-10 km深度的高衰减量相关，这表明在高衰减带中，弹性变形占主导。在箱根火山下方10–20 km深度处成像的中等衰减的垂直下体积与山下的部分融化区域的顶部相连。富士通过深度约25 km的水平下通道进入≥30 km的深度。下地壳中的DLFE和与流体有关的活动（例如上地壳中的地震群）发生在该体积中。因此，该区域被解释为一条流体路径，