Gravity waves and acoustic waves generated by submarine earthquakes

Yamamoto, Tokuo

doi:10.1016/0261-7277(82)90016-x

Cited by 50 publications

(47 citation statements)

References 3 publications

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“…As anticipated in §2.1, a good approximation for the HA wavenumbers β n = iβ n is 16) see for example Yamamoto (1982), Stiassnie (2010) and Renzi & Dias (2014a). As a consequence, the eigenmodes (2.9) become…”

Section: Model Equationsmentioning

confidence: 77%

“…This means that the dynamics away from the source is dominated by the propagating component p p n , which is stronger than the trapped longshore component p t n of figure 4. Figure 5 also reveals that shorter HA waves travel faster, followed by a tail of longer waves (see also Yamamoto 1982;Renzi & Dias 2014b). This is opposite to the dispersive E. Renzi behaviour of gravity waves (Mei et al 2005).…”

Section: Numerical Examplementioning

confidence: 78%

“…parallel to bathymetry, but decays along x regardless of the water depth! This is different from the known dynamics in 2D, where each nth HA mode decays only in regions where the water depth is less than the cut-off value (2n − 1)πc/(2ω), see Yamamoto (1982); Stiassnie (2010); ; Kadri (2015). The analytical structure of (3.27) reveals that no simple harmonic HA waves can exist when |α n | ω/c, i.e.…”

Section: Solution For Cylindrical Topographymentioning

confidence: 79%

“…The 0th mode represents the surface gravity wave, which is hardly influenced by compressibility (Yamamoto 1982;Stiassnie 2010;Renzi & Dias 2014a). The higher modes n > 0 represent the associated HA waves, which for given frequency ω can be either evanescent or propagating at large |x|, depending on the system parameters (see §3).…”

Section: Model Equationsmentioning

confidence: 99%

“…The eigenfunctions (2.9) are a normalised form of those used in the solution of Sammarco et al (2013), namely f n = cosh[β n (z + h)]/ cosh(β n h). Note that the latter expression becomes singular for z < 0 in the limit β n → i(2n − 1)π/(2h), which describes the HA modes of the system (Yamamoto 1982;Stiassnie 2010). Such a singularity would prevent us from obtaining an analytical representation of the HA field quantities (though a numerical solution is still possible, see Sammarco et al 2013).…”

Section: Model Equationsmentioning

confidence: 99%

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Hydro-acoustic frequencies of the weakly compressible mild-slope equation

Renzi

2016

J. Fluid Mech.

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This draft was prepared using the LaTeX style file belonging to the Journal We present a novel analytical solution for hydro-acoustic waves in a weakly compressible fluid over a slowly varying bottom. Application of a multiple-scale perturbation technique and matched asymptotic analysis leads to a uniform analytical solution of the depthaveraged governing equations in three dimensions. We show that the slow depth variation plays a leading-order effect on the evolution of the normal mode amplitude and direction. This dynamics is much richer than the two-dimensional limit analysed in previous studies.For tsunamigenic disturbances, we show that the hydro-acoustic wave field is made up by longshore trapped and offshore propagating components, which were not explicated in previous work. For a plane beach, we find an exact analytical solution of the model equation in terms of integrals of Bessel functions. Our model offers a physical insight into the evolution of hydro-acoustic waves of interest for the design of tsunami early warning systems.

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Section: Model Equationsmentioning

confidence: 77%

Section: Numerical Examplementioning

confidence: 78%

Section: Solution For Cylindrical Topographymentioning

confidence: 79%

Section: Model Equationsmentioning

confidence: 99%

Section: Model Equationsmentioning

confidence: 99%

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Hydro-acoustic frequencies of the weakly compressible mild-slope equation

Renzi

2016

J. Fluid Mech.

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Traveltime delay and initial phase reversal of distant tsunamis coupled with the self‐gravitating elastic Earth

2014

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Systematic tsunami traveltime delays of up to 15 min relative to the numerically simulated long waves from the 2010 Chilean and 2011 Tohoku-Oki earthquakes were widely observed at deep ocean tsunamimeters. Enigmatic small negative phases appearing before the main peak were commonly found only at the trans-oceanic locations. The frequency dependence of the measured tsunami phase velocities shows reverse dispersions at long periods, i.e., the tsunami speed becomes slower at periods beyond 1000 s. This is consistent with the phase velocities of a tsunami mode coupled with a self-gravitating elastic Earth, suggesting that the effects of compression and dilatation of seawater, elastic tsunami loadings on a solid Earth, and the geopotential variations associated with the motion of mass during tsunami propagation are responsible for the traveltime delays and the initial negative phases. Simple 1-D tsunami propagation tests confirm that the reverse dispersion creates a small negative phase that precedes the main peak at large distances. A new method to simulate tsunami waveforms on real ocean bathymetry that takes into account seawater compressibility, the elasticity of the Earth, and geopotential perturbations has been developed by applying a phase correction to the simulated long waves. The simulated waveforms, in which phase corrections are applied for the dispersion effects, accurately reproduce the observed waveforms, including a small initial negative phase that appears at distant locations. The traveltime difference between the observed and simulated waveforms has been decreased to less than 5 min and the waveform difference between them remarkably diminishes.

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Deep ocean water transport by acoustic-gravity waves

Kadri

2014

J. Geophys. Res. Oceans

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Acoustic-gravity waves are compression-type waves propagating with amplitudes governed by the restoring force of gravity. They are generated, among others, by wind-wave interactions, surface waves interactions, and submarine earthquakes. We show that acoustic-gravity waves contribute to deep ocean currents and circulation; they cause chaotic flow trajectories of individual water parcels, which can be transported up to a few centimeters per second.

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Gravity waves and acoustic waves generated by submarine earthquakes

Cited by 50 publications

References 3 publications

Hydro-acoustic frequencies of the weakly compressible mild-slope equation

Hydro-acoustic frequencies of the weakly compressible mild-slope equation

Traveltime delay and initial phase reversal of distant tsunamis coupled with the self‐gravitating elastic Earth

Deep ocean water transport by acoustic-gravity waves

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