Infrasound from Earthquakes,Tsunamis and Volcanoes

Garcés, Milton; Pichon, Alexis Le

doi:10.1007/978-0-387-30440-3_286

Cited by 5 publications

(2 citation statements)

References 64 publications

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“…RedVox has been used in a variety of environments, demonstrating its flexibility as a sensing platform. For example, the app has been deployed in the laboratory for microphone frequency response analysis [4], on ground stations for earthquake, tsunami, hypersonic re-entry, and volcano detection [9][10][11], on high-altitude balloons above surface chemical explosions [8], or even plummeting from the stratosphere [2]. In static deployments where the phones have a cellular signal, RedVox can stream the data in near real-time to a user's AWS S3 bucket; if a phone is moving in and out of cellular range, it can store data locally and then backfill once its signal strength is adequate.…”

Section: Introductionmentioning

confidence: 99%

RedVox: evolution and applications of a smartphone infrasound recorder

Liu,

Garces,

Christe

et al. 2024

Signal Processing, Sensor/Information Fusion, and Target Recognition XXXIII

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Attritable sensor systems with microphones are ubiquitous and can detect a variety of moving targets from ground vehicles to unmanned autonomous systems (UAS), aircraft, and spacecraft. Smartphone platforms have open data collection interfaces and can use cellular, Wi-Fi, and other public communications to relay data. In addition, acoustic signatures are more difficult to mask than transmissions in radio-frequency bands, making sound a passive complement to RF in an early warning system. This presentation discusses the development, deployment, and ongoing AI/ML work behind RedVox, a smartphone app available through the Apple App Store and Google Play Store. RedVox records data using the smartphone's onboard sensors, including the accelerometer, gyroscope, magnetometer, barometer, and microphone; these data packets can be streamed to interested parties in real-time and analyzed online using RedVox's open-source software tools. One of RedVox's unique features is the ability to collect infrasonic data at frequencies below human hearing, which has been shown to detect natural disasters, explosions, and motorized vehicles. The RedVox app is rapidly deployable at scale in regions of interest. Two current focus areas are Guam and Coconut Island in Oahu, where networks of smartphones can perform edge processing and dispersed sensing of airborne and maritime targets. The RedVox ecosystem has matured over the past decade across diverse environments and currently provides advanced edge and cloud analytics. Further development could lead to a lightweight machine learning model that flags anomalous entities for human review, offering a resilient ad hoc sensor network for defense or emergency response applications.

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Section: Introductionmentioning

confidence: 99%

RedVox: evolution and applications of a smartphone infrasound recorder

Liu,

Garces,

Christe

et al. 2024

Signal Processing, Sensor/Information Fusion, and Target Recognition XXXIII

View full text Add to dashboard Cite

show abstract

“…Since acoustic attenuation generally increases with increasing frequency, infrasound waves can propagate over much greater distances than audible sound. Ground-based monitoring of infrasound has been widely used for decades, successfully detecting signals from numerous sources including earthquakes, tsunamis, volcanoes, bolides Le Pichon, 2009), and explosions (Pilger et al, 2021). Ground-based infrasound monitoring is also used (alongside other detection methods) by the global International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty (Vergoz et al, 2022).Airborne infrasound, on the other hand, has not been as extensively studied or utilized.…”

mentioning

confidence: 99%

Acoustic Waves From a Distant Explosion Recorded on a Continuously Ascending Balloon in the Middle Stratosphere

Popenhagen,

Bowman,

Zeiler

et al. 2023

Geophysical Research Letters

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A helium‐filled mylar balloon carrying a smartphone and infrasound sensors ascended to a stratospheric height of 35 km over the surface detonation of a chemical explosive, with a total acoustic propagation distance of 127 km. The smartphone was configured to collect multi‐modal data at high rates from internal sensors. Analysis of the data shows successful collection of the explosion signal by both the smartphone's microphone and its accelerometers, the first from an ascending balloon. Comparison of the acoustic signal with that collected by other infrasound sensors, both airborne and ground‐based, provides insight into the possibilities and limitations of collecting acoustic data from the stratosphere.

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Optical observations of meteors generating infrasound: Weak shock theory and validation

2015

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We have recorded a data set of 24 cm sized meteoroids detected simultaneously by video and infrasound to critically examine the ReVelle (1974) weak shock meteor infrasound model. We find that the effect of gravity wave perturbations to the wind field and updated absorption coefficients in the linear regime on the initial value of the blast radius (R 0 ), which is the strongly nonlinear zone of shock propagation near the body and corresponds to energy deposition per path length, is relatively small (<10%). Using optical photometry for ground truth for energy deposition, we find that the ReVelle model accurately predicts blast radii from infrasound periods (τ) but systematically underpredicts R 0 using pressure amplitude. If the weak shock to linear propagation distortion distance is adjusted as part of the modeling process, we are able to self-consistently fit a single blast radius value for amplitude and period. In this case, the distortion distance is always much less (usually just a few percent) than the value of 10% assumed in the ReVelle model. Our study shows that fragmentation is an important process even for centimeter-sized meteoroids, implying that R 0 , while a good measure of energy deposition by the meteoroid, is not a reliable means of obtaining the meteoroid mass. We derived an empirical period-blast radius relation of the form R 0 = 15.4τ À 0.5 (τ ≤ 0.7 s) and R 0 = 29.1τ À 11.6 (τ > 0.7 s) appropriate to centimeter-sized meteoroids. Our observations suggest that meteors having blast radii as small as 1 m are detectable infrasonically at the ground, an order of magnitude smaller than previously considered.

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Infrasound from Earthquakes,Tsunamis and Volcanoes

Cited by 5 publications

References 64 publications

RedVox: evolution and applications of a smartphone infrasound recorder

RedVox: evolution and applications of a smartphone infrasound recorder

Acoustic Waves From a Distant Explosion Recorded on a Continuously Ascending Balloon in the Middle Stratosphere

Optical observations of meteors generating infrasound: Weak shock theory and validation

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