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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Seismic scattering and absorption mapping of debris flows, feeding paths, and tectonic units at Mount St. Helens volcano
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Seismic scattering and absorption mapping of debris flows, feeding paths, and tectonic units at Mount St. Helens volcano

机译：圣海伦斯火山的泥石流，进给路径和构造单元的地震散射和吸收图

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摘要

Frequency-dependent peak-delay times and coda quality factors have been used jointly to separate seismic absorption from scattering quantitatively in Earth media at regional and continental scale; to this end, we measure and map these two quantities at Mount St. Helens volcano. The results show that we can locate and characterize volcanic and geological structures using their unique contribution to seismic attenuation. At 3 Hz a single high-scattering and high-absorption anomaly outlines the debris flows that followed the 1980 explosive eruption, as deduced by comparison with remote sensing imagery. The flows overlay a NNW-SSE interface, separating rocks of significant varying properties down to 2-4 km, and coinciding with the St. Helens Seismic Zone. High-scattering and high-absorption anomalies corresponding to known locations of magma emplacement follow this signature under the volcano, showing the important interconnections between its feeding systems and the regional tectonic boundaries. With frequency increasing from 6 to 18 Hz the NNW-SSE tectonic/feeding trends rotate around an axis centered on the volcano in the direction of the regional-scale magmatic arc (SW-NE). While the aseismic high-scattering region WSW of the volcano shows no evidence of high absorption, the regions of highest-scattering and absorption are consistently located at all frequencies under either the eastern or the south-eastern flank of the volcanic edifice. From the comparison with the available geological and geophysical information we infer that these anomalies mark both the location and the trend of the main feeding systems at depths greater than 4 km. (C) 2016 Elsevier B.V. All rights reserved.
机译：频率相关的峰值延迟时间和尾声质量因子已被联合用于在区域和大陆范围内量化地层中地震吸收与散射的分离;为此，我们在圣海伦斯火山上测量并绘制了这两个量。结果表明，我们可以利用火山和地质结构对地震衰减的独特作用来定位和表征。在3 Hz时，一个高散射和高吸收的异常勾勒出了1980年爆炸后爆发的泥石流，这是通过与遥感影像的比较得出的。流动覆盖了NNW-SSE界面，分离了具有显着变化特性的岩石，直至2-4 km，并与圣海伦斯地震带重合。与火山岩位置已知位置相对应的高散射和高吸收异常遵循了火山下方的这一特征，显示了其进食系统与区域构造边界之间的重要联系。随着频率从6 Hz增至18 Hz，NNW-SSE的构造/觅食趋势围绕着以火山为中心的轴沿区域性岩浆弧（SW-NE）方向旋转。尽管火山的地震高散射区WSW没有显示出高吸收的迹象，但散射最高和吸收高的区域始终位于火山大厦东侧或东南侧的所有频率处。通过与可用的地质和地球物理信息的比较，我们可以推断出这些异常标志了深度大于4 km的主要饲喂系统的位置和趋势。 （C）2016 Elsevier B.V.保留所有权利。

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