Rayleigh and Sezawa Waves Generated by Explosions

Kubotera, Akira

doi:10.4294/jpe1952.5.33

Cited by 4 publications

(3 citation statements)

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“…Therefore, regardless of the frequency, there is a fundamental Rayleigh mode whose speed V R1 tends, in the limit of LF, toward the speed of a Rayleigh wave at the free surface of the bedrock (so typically, around 2500 m/s here), and in the limit of HF, toward the speed of a Rayleigh wave at the free surface of the sediments (so typically, around 190 m/s here). The energy associated with this Rayleigh mode, also known as the M 1 wave [61], [62], is mainly trapped below the sediment surface and decreases exponentially with depth. The penetration depth in the bedrock decreases with increasing sedimentary layer thickness for a given frequency [60].…”

Section: ) Modal Acoustic Propagationmentioning

confidence: 99%

“…Depending on the considered frequency range, there can also be an infinite number of higher order modes, known as Sezawa modes [62], [60] with a low cutoff frequency. Their phase speed lies between V S rock (at the LF limit) and V S sed (at the HF limit).…”

Section: ) Modal Acoustic Propagationmentioning

confidence: 99%

“…Their phase speed lies between V S rock (at the LF limit) and V S sed (at the HF limit). As illustrated in [62] for the mode 2, also known as the M 2 wave [61], [62], the energy associated with these modes has a fairly significant penetration depth in the bedrock in particular close to the cutoff frequencies, while for HF the energy is rather concentrated in the sedimentary layer with a penetration depth of one λ in the basement. The sinusoidal nature of the displacement amplitudes of the Rayleigh-Sezawa modes in the sedimentary layer is much more pronounced for the higher Sezawa modes at large h sed /λ values [60].…”

Section: ) Modal Acoustic Propagationmentioning

confidence: 99%

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Assessment of Risks Induced by Countermining Unexploded Large-Charge Historical Ordnance in a Shallow Water Environment—Part II: Modeling of Seismo-Acoustic Wave Propagation

Favretto-Cristini

Wang

Cristini

et al. 2022

IEEE J. Oceanic Eng.

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The goal of this work presented in a two-companion paper is to pave the way for reliably assessing the risks of damage to buildings on the shore, induced by the detonation of large-charge historical ordnance (i.e., countermining) in variable shallow water environments. Here, we focus on the impact of the marine environment, more specifically the unconsolidated sedimentary layer, on detonation-induced seismo-acoustic wave propagation. We rely on a multidisciplinary cross-study including real data obtained within the framework of a countermining campaign, and numerical simulations of the seismo-acoustic propagation using a spectral-element method. We first develop a strategy relying on physical insights into the different kind of waves that can propagate in a coastal environment, to provide clues for a computational cost reduction. The geological surveys and the hydroacoustic measurements provide input data for the 3-D axisymmetric modeling of wave propagation. The numerical simulations, obtained for one specific source-receiver path with a variable sedimentary facies, are compared with the real seismic data induced by the detonation of a charge either on the seabed, or in the water column, and recorded on the coast. Numerical analysis sheds light on the strong interaction between surface waves and the sedimentary facies. The short-scale and deep Manuscript

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Section: ) Modal Acoustic Propagationmentioning

confidence: 99%

Section: ) Modal Acoustic Propagationmentioning

confidence: 99%