Physics of Tsunamis

Левин, Б. В.; Носов, М. А.

doi:10.1007/978-3-319-24037-4

Cited by 104 publications

(105 citation statements)

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“…It would be interesting to include the curvature in our calculation, either as a simple correction factor on the distances, or by trying to derive ray equations from the shallow water wave equations in spherical coordinates, which can be found e.g. in [75]. As this work studied the focusing of the tsunami waves far from the coasts, in the linear regime, it would of course also be of interest to extend the theory to nonlinear waves, where the interplay between the focusing we describe in this thesis and the nonlinearities could only improve our understanding of the run-up.…”

Section: Discussionmentioning

confidence: 99%

Random focusing of tsunami waves

et al. 2015

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Branched flow is a universal phenomenon of random focusing that occurs in wave or particle flows that propagate in weakly scattering, correlated random media. The consecutive effect of small random forces leads to regions of strong focusing which have the appearance of branches and originate from the formation of random caustics. This phenomenon has been experimentally and theoretically studied in various systems, ranging from experimental observations in electronic microdevices on the micrometer scale to theoretical predictions for the propagation of sound waves in the ocean, on the scale of thousands of kilometers. Reconstructions of the tsunami of March 2011 exhibited strong fluctuations in the tsunami height, associated with a filamentation of the flow, reminiscent of the structures observed for example in electron flows in semiconductor microstructures. This raises the question, to what extent are the same mechanisms at play in these very different physical systems and what impact do they have for tsunami predictions. Developing a theory of random caustics and branching in tsunami waves is the main purpose of this thesis.We will start by showing that tsunamis indeed exhibit strong focusing even when propagating over a weakly scattering region of the ocean floor. We will therefore develop the stochastic theory for the characteristic length scale on which random caustics appear in the propagations of tsunamis described by ray equations. We then confirm that the focusing regions of tsunami waves follow the scaling predicted by stochastic ray dynamics with respect to the parameters of the bathymetry. We thus show that tsunamis are indeed subject to the phenomenon of branched flow. We will furthermore demonstrate that, due to the fact that already tiny bathymetry fluctuations can be a source of branched flow, bathymetry has a severe impact on the predictability of tsunami heights. Small uncertainties in the knowledge of the ocean's bathymetry can lead to drastically wrong predictions.Because the ocean floor bathymetry is known to exhibit anisotropies and to be correlated on several length scales due to the various geological processes contributing to its formation, we later extend the general theory of branched flows to systems where the random medium is correlated on more than one single length-scale, both for tsunami waves and Hamiltonian rays, as it is also relevant to many other systems. We calculate how such correlations affect the typical length scale of branching. Our theory is then applicable to a large variety of correlation functions, either anisotropic or isotropic with multiple correlation lengths. We conclude with a proposal for an experiment which scales a tsunami event down to the size of a tank in a laboratory to study the focusing effect of bathymetry structures. Such a tool could be useful in tsunami studies and forecasting and it would allow us to experimentally verify our theoretical and numerical results on random focusing of tsunami waves.3

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Section: Discussionmentioning

confidence: 99%

Random focusing of tsunami waves

et al. 2015

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“…To estimate the possible parameters of the water surface displacement when a meteorite falls, we use a simplified model in which the generation of waves by a meteorite entering the water is parameterized by certain initial conditions (Ward and Asphaug, 2000;Mirchina and Pelinovsky, 1988;Kharif and Pelinovsky, 2005;Levin and Nosov, 2009;Torsvick et al, 2010). It is suggested that in the initial stage of a crater formation a meteorite, vertically entering the water, creates a radially symmetrical cavity on the water surface, which can be described by a simple function:…”

Section: Introductionmentioning

confidence: 99%

“…According to Levin and Nosov (2009) about 16% of the kinetic energy of the falling body is converted into the energy of tsunami waves. The parameter α is 1.27, and the value of q and δ is calculated as follows:…”

Section: Introductionmentioning

confidence: 99%

Numerical modeling of the 2013 meteorite entry in Lake Chebarkul, Russia

Козелков

Kurkin

Pelinovsky

et al. 2017

Nat. Hazards Earth Syst. Sci.

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Abstract. The results of the numerical simulation of possible hydrodynamic perturbations in Lake Chebarkul (Russia) as a consequence of the meteorite fall of 2013 (15 February) are presented. The numerical modeling is based on the Navier-Stokes equations for a two-phase fluid. The results of the simulation of a meteorite entering the water at an angle of 20 • are given. Numerical experiments are carried out both when the lake is covered with ice and when it is not. The estimation of size of the destructed ice cover is made. It is shown that the size of the observed ice hole at the place of the meteorite fall is in good agreement with the theoretical predictions, as well as with other estimates. The heights of tsunami waves generated by a small meteorite entering the lake are small enough (a few centimeters) according to the estimations. However, the danger of a tsunami of meteorite or asteroid origin should not be underestimated.

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“…Les tsunamis sont le plus souvent générés par la déformation du fond marin liée aux séismes (Dotsenko et Soloviev, 1995 ;Levin et Nosov, 2008). Le principe de la génération des tsunamis est présenté en Figure 1 ; -pour estimer la déformation du sol.…”

Section: Introductionunclassified

Déplacements et rotations du sol lors de forts séismes à proximité de failles actives : apports des capteurs accélérométriques

Javelaud¹

2016

Rev. Fr. Geotech.

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Résumé -Lors de forts séismes ou près de failles actives, le sol subit des déplacements et rotations dont les amplitudes peuvent être importantes à la fois pendant et après le séisme. L'appréciation de ces mouvements du sol est fondamentale pour la prédiction des tsunamis, l'estimation des déformations du sol, ainsi que pour le dimensionnement des structures qui se trouvent à proximité de failles actives. Les déplacements peuvent être mesurés par différents moyens tels que topographiques ou géodésiques (InSAR, GPS), mais ces méthodes classiques se limitent essentiellement à la surface de la Terre et aux endroits où le géomètre peut accéder. Dans cet article, nous présentons la possibilité de calculer les déplacements ainsi que la rotation permanente du sol à partir d'accélérogrammes. L'intérêt d'utiliser les accéléromètres en complément des méthodes habituelles réside dans le nombre important d'instruments installés à l'échelle mondiale en des endroits très variés (à la surface, dans les structures, au fond de puits ou sur le fond marin) ainsi qu'au très faible pas d'échantillonnage des enregistrements, en général 100 à 200 Hz. La méthode proposée est tout d'abord validée en des lieux où coexistent des accéléromètres et des mesures classiques. Cela permet de vérifier la justesse des déplacements et rotations permanentes calculés, puis d'utiliser cette méthode là où seuls les accéléromètres peuvent être installés. Des implications pour le dimensionnement des structures sont présentées. Mots clés : Sismologie du mouvement fort / accélérogramme / déplacement / rotationAbstract -Near-field displacement and rotations estimated from strong-motion accelerometers. During large earthquakes, tectonic movements along faults generate in their near-field important deformations, including transitory and permanent displacements, as well as tilting of the surface. An accurate knowledge of the ground motions is important for tsunami prediction, the estimation of ground strain, as well as for the design of structures. Several methods exist to quantitatively measure the ground deformation generated in the near-field of large earthquakes. They include topographic surveys and geodetic techniques (InSar, GPS), but these methods are limited to the Earth surface and to places where the surveyors have access. Here, we show the possibility to estimate coseismic displacements and permanent rotations from strong-motion accelerometers. Using accelerometers besides traditional techniques is interesting because of the large number of instruments deployed worldwide in a variety of different places (on the surface, within structures, boreholes or on the seafloor), and also because of the high sampling frequency of the records, usually 100 to 200 Hz. The proposed method is validated in places where collocated accelerometers and externals measurements exist. It allows estimating the accuracy of the calculated displacements and rotations, then to use this method where accelerometers only can be installed. The implications for the design of structu...

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Physics of Tsunamis

Cited by 104 publications

References 0 publications

Random focusing of tsunami waves

Random focusing of tsunami waves

Numerical modeling of the 2013 meteorite entry in Lake Chebarkul, Russia

Déplacements et rotations du sol lors de forts séismes à proximité de failles actives : apports des capteurs accélérométriques

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