We analyze seismic tremor recorded during eruptive activity over the course of the 2016–2017 eruption of Bogoslof volcano, Alaska. Only regional recordings of the tremor wavefield exist for Bogoslof, making it a challenge to place the recordings in context with other eruptions that are normally captured by local seismic data. We apply a technique of time-frequency polarization analysis to three-component seismic data to reveal the wavefield composition of Bogoslof eruption tremor. We find that at regional distances, the tremor is dominated by P-waves in the band from 1.5 to 10 Hz. Using this information, along with an enriched Bogoslof earthquake catalog, we obtain estimates of average reduced displacement ( D R ) for eruption tremor during 25 of the 70 Bogoslof events. D R reaches as high as approximately 40 cm 2 for two of the major events, similar to other VEI~3 eruptions in Alaska. Overall, average reduced displacement displays a weak correlation to plume height during the first half of the 9-month-long eruption sequence, with a few notable exceptions. The two events with the highest D R values also generated measurable eruption tremor at very-long-periods (VLP) between 0.05 and 0.15 Hz.

中文翻译：

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博戈斯洛夫火山的协同喷发震颤：区域距离的地震波场组成

我们分析了 2016 年至 2017 年阿拉斯加博戈斯洛夫火山喷发期间喷发活动期间记录的地震震颤。Bogoslof 仅存在震颤波场的区域记录，这使得将记录与通常由当地地震数据捕获的其他火山喷发一起放置是一个挑战。我们将时频极化分析技术应用于三分量地震数据，以揭示 Bogoslof 喷发震颤的波场组成。我们发现，在区域距离内，震颤以 1.5 到 10 Hz 频带内的 P 波为主。使用这些信息以及丰富的 Bogoslof 地震目录，我们获得了 70 次 Bogoslof 事件中的 25 次喷发震颤的平均减少位移 (DR) 的估计值。对于两个主要事件，DR 高达约 40 cm 2，类似于阿拉斯加的其他 VEI~3 喷发。总体而言，在长达 9 个月的喷发序列的前半段，平均减少的位移与羽流高度的相关性较弱，但有一些值得注意的例外。具有最高 DR 值的两个事件还在 0.05 和 0.15 Hz 之间的超长周期 (VLP) 下产生了可测量的喷发震颤。