Intrinsic Directional Information of Ground Roll Waves

Hazelwood, Richard A.; Macey, Patrick

doi:10.1007/978-1-4939-2981-8_53

Cited by 11 publications

(12 citation statements)

References 3 publications

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“…If this roll direction can be detected by small creatures they may find it useful to determine which way to hunt or flee. As was discussed by Hazelwood & Macey [25] this is feasible for creatures with 3 axis inertial sensors, even when small by comparison to a wavelength.…”

Section: The Extra Information In the Vector Field May Be Critical Fomentioning

confidence: 92%

Modeling Water Motion near Seismic Waves Propagating across a Graded Seabed, as Generated by Man-Made Impacts

Hazelwood¹,

Macey²

2016

JMSE

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Seismic interface waves generated by seabed impacts are believed to have biological importance. Various wave types are of interest to seismologists, who can minimize the unwanted, but often dominant, ground roll waves with suitable instrumentation. Waves made by dredging and piling have been measured using geophones and found to be of this interface type, which propagate much more slowly than the pressure waves in the water column above. Short interface wavelets of a few cycles were modeled using transient finite element analysis (FEA). Wavelets with low losses have been modeled using graded sediment data from the literature. They do not radiate energy away from the interface because the evanescent acoustic pressures they generate decay rapidly with distance from the seabed. Associated water particle velocities are much greater than would be expected from similar acoustic pressure measurements in a free field. This motion is significant to aquatic life which is dependent on inertial sensors (otoliths, etc.) to respond to the environment. Additional amplification of the horizontal seabed motion of the adjacent water is predicted for a short seismic wavelet modeled in a graded solid seabed. Further recent analysis studied the distribution of the energy flux within the sediment layers.

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Section: The Extra Information In the Vector Field May Be Critical Fomentioning

confidence: 92%

Modeling Water Motion near Seismic Waves Propagating across a Graded Seabed, as Generated by Man-Made Impacts

Hazelwood¹,

Macey²

2016

JMSE

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“…The work published earlier [17] using a shear speed depth profile from data published by Hamilton [21] and the polynomial force function of Equation (5) gave more complex wavelet shapes. However, the intriguing morphing characteristic was clear within the animated results presented at various conferences by Hazelwood [36,37]. Figure 9 shows results from the earlier FE model pwb42, based on the Hamilton data.…”

Section: Wavelets In a Hamilton Profile Fe Model Are Also Seen To Mormentioning

confidence: 85%

Optimal Transmission of Interface Vibration Wavelets—A Simulation of Seabed Seismic Responses

Hazelwood¹,

Macey²,

Robinson

et al. 2018

JMSE

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Seismic interface waves generated by seabed impacts are believed to have biological importance. Previous work on the effects of ocean piling and dredging studied water motion adjacent to the seabed, using sediment measurements as reviewed in the literature. This new modelling work has idealised the sediment data to a simple model with few parameters, and has shown how this leads to filtration of the applied energy to propagate simple seismic vibration wavelets. These special wavelets remain compact with high peak levels of the associated water particle velocity as they ripple outward, and provide a means of assessing the worst-case environmental impact. The form of this wavelet morphs from a hump shape to a dip and back, via intermediate forms which are here described in mathematical terms based on the Ricker form. Whilst the model structure is idealised it is much closer to reality than the Rayleigh and Scholte half-space models, but with only two more parameters required. The resultant wavelet peaks are propagated with values given by the optimal limit case of cylindrical spreading (ignoring absorption) which results in a relatively widespread impact.

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“…The current work shows that hermit crabs are sensitive to broad range of frequencies < 410 Hz. The low frequency range is accentuated in the propagation of anthropogenic produced surface waves (Hazelwood, 2012;Hazelwood and Macey, 2015). It is likely that the vibrations summarised in Table 2 are also detectable by other crustacean species, which have similar sensitivities to P. bernhardus (Figure ).…”

Section: Relation To Anthropogenic Vibration Levelsmentioning

confidence: 99%

“…Within this, the impact of seabed vibration upon marine organisms has been largely neglected even though many activities involve direct contact with the seabed, for example pile driving and drilling. These produce substrate-borne vibrations which can travel as compressional (longitudinal), transverse (shear) or surface (Rayleigh or 'ground roll') waves (Aicher and Tautz, 1990;Hazelwood and Macey, 2015;Markl, 1983), with energy being transmitted in one or multiple waveforms depending on the substrate type, boundary layers, and connection to the substrate (Aicher and Tautz, 1990). The energy of low frequency Rayleigh waves in particular, may travel large distances from the source (Brownell, 1977), trapped within the surface seabed with minimal attenuation (Hazelwood and Macey, 2015).…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of Pagurus bernhardus (L.) to substrate-borne vibration and anthropogenic noise

Roberts

Cheesman²,

Elliott

et al. 2016

Journal of Experimental Marine Biology and Ecology

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Despite the prevalence of vibration produced by anthropogenic activities impacting the seabed there are few data and little information as to whether these are detected by crustaceans and whether they interfere with their behaviour. Here the sensitivity of unconditioned Pagurus bernhardus to substrate-borne vibration was quantified by exposure to sinusoidal vibrations of 5 -410 Hz of varied amplitudes using the staircase method of threshold determination, with threshold representing the detection of the response and two behavioural responses used as reception indicators: movement of the second antenna and onset or cessation of locomotion. Thresholds were compared to measured vibrations close to anthropogenic operations and to the time in captivity prior to tests. Behaviour varied according to the strength of the stimulus with a significant difference in average threshold values between the two behavioural indicators, although there was overlap between the two, with overall sensitivity ranging from 0.09 -0.44 m s -2 (root mean squared, RMS). Crabs of shortest duration in captivity prior to tests had significantly greater sensitivity to vibration, down to 0.02 m s -2 (RMS). The sensitivity of P. bernhardus fell well within the range of vibrations measured near anthropogenic operations. The data indicate that anthropogenic substrate-borne vibrations have a clear effect on the behaviour of a common marine crustacean. The study emphasises that these vibrations are an important component of noise pollution that requires further attention to understand the long term effects on marine crustaceans.

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Intrinsic Directional Information of Ground Roll Waves

Cited by 11 publications

References 3 publications

Modeling Water Motion near Seismic Waves Propagating across a Graded Seabed, as Generated by Man-Made Impacts

Modeling Water Motion near Seismic Waves Propagating across a Graded Seabed, as Generated by Man-Made Impacts

Optimal Transmission of Interface Vibration Wavelets—A Simulation of Seabed Seismic Responses

Sensitivity of Pagurus bernhardus (L.) to substrate-borne vibration and anthropogenic noise

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