Outdoor measurements of spherical acoustic shock decay

Young, Sarah; Gee, Kent L.; Neilsen, Tracianne B.; Leete, Kevin M.

doi:10.1121/1.4929928

Cited by 8 publications

(5 citation statements)

References 19 publications

(23 reference statements)

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“…It is important to note that while the Maekawa [1968] chart is commonly used as a first-order noise reduction estimate regardless of source-receiver geometry [e.g. Ekici and Bougdah 2003;Ettouney and Fricke 1973;Plotkin et al 2009;Scholes et al 1971;Vu 2007;Young et al 2015], Maekawa [1968] states that it is intended for cases where the source and receivers are in the air. This condition allows direct comparison between diffracted measurements and free-field estimates since the influence of ground reflection can be avoided.…”

Section: Figurementioning

confidence: 99%

Evaluating the applicability of a screen diffraction approximation to local volcano infrasound

et al. 2021

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Atmospheric acoustic waves from volcanoes at infrasonic frequencies (0.01–20 Hz) can be used to estimate source parameters for hazard modeling, but signals are often distorted by wavefield interactions with topography, even at local recording distances (<15 km). We present new developments toward a simple empirical approach to estimate attenuation by topographic diffraction at reduced computational cost. We investigate the applicability of a thin screen diffraction relationship developed by Maekawa [1968, doi: https://doi.org/10.1016/0003-682X(68)90020- 0]. We use a 2D axisymmetric finite-difference method to show that this relationship accurately predicts power losses for infrasound diffraction over an idealized kilometer-scale screen; thus validating the scaling to infrasonic wavelengths. However, the Maekawa relationship overestimates attenuation for realistic volcano topography (using Sakurajima Volcano as an example). The attenuating effect of diffraction may be counteracted by constructive interference of multiple reflections along concave volcano slopes. We conclude that the Maekawa relationship is insufficient as formulated for volcano infrasound, and suggest modifications that may improve the prediction capability.

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Section: Figurementioning

confidence: 99%

Evaluating the applicability of a screen diffraction approximation to local volcano infrasound

et al. 2021

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“…For example, peak pressure of a weak shock (e.g. Muhlestein et al 2012;Rogers 1977;Young et al 2015) decays with a power of radius slightly larger than 1. Such a dependency may be observed in the presented data (Figure 8a).…”

Section: Discussionmentioning

confidence: 99%

“…A more in‐depth analysis that focuses on the complete seismo‐acoustic data set of the presented experiments may help here. For example, peak pressure of a weak shock (e.g., Muhlestein et al., 2012; Rogers, 1977; Young et al., 2015) decays with a power of radius slightly larger than 1. Such a dependency may be observed in the presented data (Figure 8a).…”

Section: Discussionmentioning

confidence: 99%

Experimental Multiblast Craters and Ejecta—Seismo‐Acoustics, Jet Characteristics, Craters, and Ejecta Deposits and Implications for Volcanic Explosions

et al. 2022

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Volcanic activity causes subsurface explosions at various depths that can have severe consequences for its environment. Explosions can have several causes, such as interaction of externally derived water in direct contact with magma (Zimanowski et al., 2015) or sudden decompression of a magma column, resulting in the rapid release of dissolved volcanic gases (Cashman & Scheu, 2015). But it is possible to evaluate some of their aspects independent from their cause. A sudden, large pressure change propagates at supersonic speed for a certain distance in a medium such as host rock, magma or atmosphere, causing deformation in elastic, plastic and brittle regimes (e.g.,

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“…For example, peak pressure of a weak shock (e.g. Young et al, 2015;Muhlestein et al, 2012;Rogers, 1977) decays with a power of radius slightly larger than 1. Such a dependency may be observed in the presented data (Figure 9a).…”

Section: Discussionmentioning

confidence: 99%

Experimental multiblast craters and ejecta — seismo-acoustics, jet characteristics, craters, and ejecta deposits and implications for volcanic explosions

Sonder¹,

Graettinger²,

Neilsen³

et al. 2022

Preprint

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Blasting experiments were performed that investigate multiple explosions that occur in quick succession in the ground and their effects on host material and atmosphere. Such processes are known to occur during volcanic eruptions at various depths, lateral locations, and energies. The experiments follow a multi-instrument approach in order to observe phenomena in the atmosphere and in the ground, and measure the respective energy partitioning. The experiments show significant coupling of atmospheric (acoustic)- and ground (seismic) signal over a large range of (scaled)distances (30--330\m, 1--10\(\m\J^{-1/3}\)). The distribution of ejected material strongly depends on the sequence of how the explosions occur. The overall crater sizes are in the expected range of a maximum size for many explosions and a minimum for one explosion at a given lateral location. The experiments also show that peak atmospheric over-pressure decays exponentially with scaled depth at a rate of \bar{d}_0 = 6.47x10^{-4} mJ^{-1/3}; at a scaled explosion depth of \(4x10^{-3} mJ^{-1/3} ca. 1% of the blast energy is responsible for the formation of the atmospheric pressure pulse; at a more shallow scaled depth of 2.75x10^{-3 \mJ^{-1/3} this ratio lies at ca. 5.5–7.5%. A first order consideration of seismic energy estimates the sum of radiated airborne and seismic energy to be up to 20\% of blast energy.

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Outdoor measurements of spherical acoustic shock decay

Cited by 8 publications

References 19 publications

Evaluating the applicability of a screen diffraction approximation to local volcano infrasound

Evaluating the applicability of a screen diffraction approximation to local volcano infrasound

Experimental Multiblast Craters and Ejecta—Seismo‐Acoustics, Jet Characteristics, Craters, and Ejecta Deposits and Implications for Volcanic Explosions

Experimental multiblast craters and ejecta — seismo-acoustics, jet characteristics, craters, and ejecta deposits and implications for volcanic explosions

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