Snow Avalanche Detection and Source Constraints Made Using a Networked Array of Infrasound Sensors
Snow Avalanche Detection and Source Constraints Made Using a Networked Array of Infrasound Sensors
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DOI：
10.1029/2020jf005741
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发表时间：
2021-03-01
影响因子：
3.9
通讯作者：
Watson, L. M.
中科院分区：
文献类型：
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作者：
Johnson, J. B.;Anderson, J. F.;Watson, L. M.
我们使用次声阵列和时间同步视频网络对一次触发雪崩(持续时间与60 S相似，跳动类似于1,100米)进行了研究，目的是了解次声产生与流动动力学之间的关系。使用标准阵列处理技术，我们将次声声源的后方位角与帧差分的地理参考视频识别的雪崩流动路径进行了比较。结果表明，次声记录开始于直接到达，然后是雪崩引发的爆炸的回声，这些回声在爆炸后35天内衰减，S。随后的次声，持续了20-30分钟的S，可以完全归因于雪崩。这些次声探测及其三角化源位置随着时间的推移而下坡，最强烈的次声似乎来自陡峭的中途悬崖带，在那里雪崩达到了超过30米/S的速度和超过5米/S的加速度(2)。将记录的次声与从视频中提取的两个候选源模型进行比较：全流运动和推进流运动。使用非负最小二乘反演法将推进的声源位置与声强时间序列进行比较，以求解并量化时变的次声声源强度。我们观察到，气流的某些部分，最明显的早期阶段和结束阶段(当粉末云膨胀和沉淀时)是次声安静的。
We studied a triggered snow avalanche (similar to 60 s in duration and with similar to 1,100 m run-out) using a network of infrasound arrays and time-synced video, with the objective of understanding the relationship between infrasound generation and flow dynamics. Using standard array processing techniques, we compared the infrasound source back azimuths with the avalanche flow path identified by frame-differenced, geo-referenced video. Results show that infrasound records begin with direct arrivals followed by echoes from the avalanche-triggering explosions and these decay within 35 s of the detonations. Subsequent infrasound, which lasts 20-30 s, could then be attributed exclusively to the avalanche. These infrasound detections, and their triangulated source locations, progress downhill over time and the most intense infrasound appears to originate from a steep, mid-path cliff band, where the avalanche reached speeds in excess of 30 m/s and accelerations of more than 5 m/s(2). The recorded infrasound was compared to two candidate source models extracted from video: total flow motion and advancing flow motion. Advancing source locations were compared to acoustic intensity time series using a nonnegative least squares inversion to solve for, and to quantify, time-varying infrasound source intensity. We observed that certain portions of the flow, most notably the early stages and the end stages (when the powder cloud was expanding and settling) were infrasonically quiet.