Effective model of gassy sediments and acoustical approach for its verification

Characterization of the gassy sediment layer in shallow water using an acoustical method: Lake Kinneret as a case study

“…On one side, the wavelength used should be small enough to provide high resolution. On the other side, as it was described earlier, at the frequencies close to the bubble resonance frequency, the reflection coefficient and attenuation coefficient become complex (Katsman et al 2021). For the frequency band used in this study, the highest resolution in d estimates was about 6 cm.…”

“…First, the behavior of acoustic waves become much more complex at resonant frequencies of the gas bubble, , which, in turn, depend on bubble size, gas thermal properties, sediment dynamic bulk and shear moduli, bulk density, and ambient hydrostatic pressure (Anderson and Hampton 1980 a , 1980 b ; Best et al 2004; Tõth et al 2015). According to recent calculations performed for sediment and bubble properties like in Lake Kinneret, are located at 4–20 kHz (Katsman et al 2021). It was shown that at signal frequencies, , less than the attenuation coefficient does not exceed .…”

“…Studies of the acoustic properties of gassy sediment have also been conducted in recent decades using different methodologies, including analysis of the resonance and nonlinear properties of bubbles in water/sediment, and in their aggregations (Abegg and Anderson 1997; Anderson et al 1998; Wilkens and Richardson 1998; Gardner 2003; Abegg et al 2008; Anderson and Martinez 2015; Tõth et al 2015; Katsman et al 2021). Recently, the analysis of the mid‐frequency (~ 1 kHz) pulse response in Lake Kinneret, including multiple reflections, was carried out to estimate the CH 4 void fraction in gassy sediment (Katsnelson et al 2017; Uzhansky et al 2020, 2022).…”

Integrated methodology for gas content assessment and prediction in shallow muddy lake sediments: acoustic mapping and correlation analysis

“…Second limitation is related to resonance (the Minnaert resonance) frequency of gas bubbles. Katsman et al [ 23 ] demonstrated that sediment sound speed, sediment attenuation coefficient, and reflection coefficient at the water-sediment interface, show non-linear frequency dependence, which are controlled by the bubble size, cumulative gas content, and corresponding resonant frequency of the gas bubble. This limits the sharpness of the pulse, which width is inversely proportional to the frequency band of the chirp.…”