Study on Infrasound From a Water Dam

Feng, Haike; Yang, Yamei; Chunchuzov, I. P.; Teng, Peng

doi:10.3813/aaa.918702

Cited by 7 publications

(27 citation statements)

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“…While the debris flow is flowing downhill along the Illgraben, infrasound continues to be recorded persistently from ≈190° N, the 45‐m waterfall at CD 1 being the most energetic source of sound. This is in agreement with experimental and theoretical studies of infrasound produced at waterfalls and dams (Feng et al, ; Kudo, ).…”

Section: Debris Flow Eventssupporting

confidence: 91%

“…By that time, it starts radiating infrasound from this fixed position that remains stable for several minutes even though the flow keeps moving downhill. This is consistent with theoretical and experimental studies of infrasound radiated at waterfalls and dams (Feng et al, 2014;Kudo, 1993).…”

Section: Mechanisms Of Infrasound Radiation By Debris Flow At Illgrabensupporting

confidence: 91%

“…For the specific case of the 29 May event, infrasound signal from this same back azimuth is recorded also between 17:19 and 17:23 UTC, when a second flow reaches the dam. Similarly to what was inferred for phase 2, we suggest that the increased infrasound radiation produced by the waterfall (Feng et al, ; Kudo, ) at the dam is the most energetic source of infrasound that is detected as a stable source although the flow keeps moving downhill.…”

Section: Debris Flow Eventssupporting

confidence: 86%

“…However, experimental observation showed that infrasound is mostly generated in fixed position, whenever waterfalls are present (Kudo, ). In particular, Feng et al () suggest that infrasound is produced at dams for water falling into the absorption pool that triggers waves radiating infrasound as a dipole source. Therefore, it is expected to have multiple sources of infrasound from rivers according to flow dynamics and channel geometry.…”

Section: Introductionmentioning

confidence: 99%

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Infrasound Array Analysis of Debris Flow Activity and Implication for Early Warning

et al. 2019

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Debris flows constitute a severe natural hazard and studies are performed to investigate triggering mechanisms and to identify and evaluate early warning systems. We present a seismoacoustic analysis of debris flow activity at Illgraben, Switzerland, with infrasound data collected with a small aperture array. Events are recorded as emergent signals of long duration, with seismic and infrasound amplitudes scaling with the flow discharge. The spectral content is stable and peaking at 8 Hz for the seismic and at 5 Hz for the infrasound that suggests two separate processes of elastic energy radiation, most likely bed‐load transport for the seismic and waves at the free surface for the infrasound. Although amplitude and frequency content of the infrasound signal are well within the processing limits, most of the signal is not showing any correlation among the array elements. We suggest that this is a consequence of the contribution of multiple sources of infrasound acting with variable amplitude and phase along the surface of the debris flow. At Illgraben, coherent infrasound is recorded only from fixed sources, corresponding to check dams within the channel. Here infrasound radiation is increased and the dams turn into predominant sources of energy. This allows to unambiguously identify the occurrence of debris flow at Illgraben with the infrasound array, from a remote and safe position and with a timing that is similar to the early warning system based on in‐channel sensors. This clearly shows how infrasound arrays could be used as an efficient early warning systems.

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Section: Debris Flow Eventssupporting

confidence: 91%

Section: Mechanisms Of Infrasound Radiation By Debris Flow At Illgrabensupporting

confidence: 91%

Section: Debris Flow Eventssupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Infrasound Array Analysis of Debris Flow Activity and Implication for Early Warning

et al. 2019

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“…This is in general agreement with Schmandt et al (2013), who studied seismic and infrasound energy radiation at Colorado river and suggested that infrasound energy was most likely radiated by waves at the water free surface. However, Marchetti et al (2019) also showed that infrasound is most efficiently radiated by the flow interaction with dams and topography changes, in agreement with experimental observation at rivers (Kudo 1993;Feng. et al 2014).…”

Section: Introductionsupporting

confidence: 84%

Numerical Modeling of Infrasound Energy Radiation by Debris Flow Events

Coco

Marchetti

Morandi

2021

Pure Appl. Geophys.

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Debris flows constitute a severe natural hazard in Alpine regions. Studies are performed to understand the event predictability and to identify early warning systems and procedures. These are based both on sensors deployed along the channels or on the amplitude of seismic and infrasound waves radiated by the flow and recorded far away. Despite being very promising, infrasound cannot be used to infer the source characteristics due to the lack of a physical model of the infrasound energy radiated by debris flows. Here the simulation of water flow along a simple channel is presented, experiencing the fall from a dam, performed within the open source simulation code OpenFOAM. The pressure perturbation within the atmosphere produced by the flow is extracted and the infrasound signature of the events as a function of the flow characteristics is defined. Numerical results suggest that infrasound is radiated immediately downstream of the dam with amplitude and period that scale with dam height and water level. Modeled infrasound waveform is interpreted as being produced mostly by waves at the water free surface developing downstream of the dam. Despite the effect of sediments is not considered in this first study and will be implemented in future investigations, numerical results obtained with this simple model are in general agreement with experimental results obtained from array analysis of infrasound data recorded at Illgraben, Switzerland. Results highlight how numerical modeling can provide critical information to define a source mechanism of infrasound energy radiation by debris-flow, that is required also to improve early warning systems.

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Seismo-acoustic analysis of debris-flow events at Illgraben (Switzerland): relating signal features to flow measurements and infrasonic source mechanisms

Belli¹,

Walter

McArdell

et al. 2022

Preprint

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We present a seismo-acoustic analysis of the debris-flow activity between 2017 and 2019 at the Illgraben catchment (Switzerland). To understand fluid dynamic processes involved in the seismo-acoustic energy generation by debris-flows, seismic and acoustic amplitudes (maximum root mean square amplitude, RMSA) and peak frequencies are compared with flow measurements (front velocity, maximum flow depth and density). Front velocity, maximum depth, peak discharge and peak mass flux show a positive correlation with both infrasonic and seismic maximum RMSA, suggesting that seismo-acoustic radiation is controlled by these flow parameters. Comparison between seismo-acoustic peak frequencies and flow parameters reveal that, unlike seismic signals, characterized by a constant peak frequency regardless of the magnitude of the flow, infrasound peak frequency decreases with increasing flow velocity, depth and discharge. Based on all collected evidence, we suggest that infrasound signals of debris-flows are generated by flow waves and water splashes that develop at the free-surface of the flow, whose dimension scales with flow magnitude. According to fluid dynamics, such surface oscillations are mostly generated wherever the flow encounters significant channel irregularities, such as topographic steps and planform steep bends, that therefore likely constitute preferential sources of infrasound. As for seismic waves, results are consistent with previous theoretical models and field observations, which attribute debris-flow seismicity to solid particle collisions, friction and fluid dynamic structures. Finally, the observed positive correlations between seismo-acoustic signal features and flow parameters highlight the potential to use infrasound and seismic measurements for debris-flow monitoring and risk management. Hosted fileessoar.10510019.1.docx available at https://authorea.com/users/534045/articles/598371seismo-acoustic-analysis-of-debris-flow-events-at-illgraben-switzerland-relating-signalfeatures-to-flow-measurements-and-infrasonic-source-mechanisms Seismo-acoustic analysis of debris-flow events at Illgraben (Switzerland): relating signal features to flow measurements and infrasonic source mechanisms

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Study on Infrasound From a Water Dam

Cited by 7 publications

References 0 publications

Infrasound Array Analysis of Debris Flow Activity and Implication for Early Warning

Infrasound Array Analysis of Debris Flow Activity and Implication for Early Warning

Numerical Modeling of Infrasound Energy Radiation by Debris Flow Events

Seismo-acoustic analysis of debris-flow events at Illgraben (Switzerland): relating signal features to flow measurements and infrasonic source mechanisms

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