Source of a Tsunami of Seismotectonic Origin

Левин, Б. В.; Носов, М. А.

doi:10.1007/978-3-319-24037-4_2

Cited by 5 publications

(10 citation statements)

References 57 publications

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“…Since then, similar meteotsunami models have been proposed for weather systems/storms interacting with the ocean (see, e.g. Murty 1984; Levin & Nosov 2009). These models correspond to the shallow-water equation (SWE) with a forcing that mimics the atmospheric pressure contributions, and are hereafter referred to as one-way coupled (OWC) as there is no feedback from the ocean to the atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Two-way coupled long-wave isentropic ocean-atmosphere dynamics

Winn

Sarmiento²,

Alferez

et al. 2023

J. Fluid Mech.

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The events following the 15 January 2022 explosions of the Hunga Tonga-Hunga Ha'apai volcano highlighted the need for a better understanding of ocean-atmosphere interactions when large amounts of energy are locally injected into one (or both). Starting from the compressible Euler equations, a two-way coupled (TWC) system is derived governing the long-wave behaviour of the ocean and atmosphere under isentropic constraint. Bathymetry and topography are accounted for along with three-dimensional atmospheric non-uniformities through their depth average over a spherical shell. A linear analysis, yielding two pairs of gravito-acoustic waves, offers explanations for phenomena observed during the Tonga event. A continuous transcritical regime (in terms of water depth) is identified as the source of large wave generation in deep water bodies, removing the singularity-driven Proudman-type resonance observed in one-way coupled models. The refractive properties, governing the interaction of the atmospheric wave with step changes in water depth, are derived to comment on mode-to-mode energy transfer. Two-dimensional global simulations modelling the propagation of the atmospheric wave (under realistic conditions on the day) and its worldwide effect on oceans are presented. Local maxima of water-height disturbance in the farfield from the volcano, linked to the atmospheric wave deformation (in agreement with observations), are identified, emphasising the importance of the TWC model for any daylong predictions. The proposed framework can be extended to include additional layers and physics, e.g. ocean and atmosphere stratification. With the aim of contributing to warning system improvement, the code necessary to simulate the event with the proposed model is made available.

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Section: Introductionmentioning

confidence: 99%

Two-way coupled long-wave isentropic ocean-atmosphere dynamics

Winn

Sarmiento²,

Alferez

et al. 2023

J. Fluid Mech.

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“…Therefore, detecting the early arrival of tsunami-generated EM signals at geomagnetic observatories has the potential to provide an advance warning of the order of tens of minutes. This represents a notable improvement on traditional tsunameter networks based on bottom pressure sensors, which are capable of only real-time detection (Levin & Nosov 2016).…”

Section: Discussionmentioning

confidence: 99%

Electromagnetic field generated by tsunamigenic seabed deformation

Renzi

Mazza

2023

J. Fluid Mech.

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We derive a mathematical model of an electromagnetic (EM) field generated by tsunamigenic seabed deformation over an ocean of constant depth. We solve the governing Maxwell equations for the EM field, coupled with a potential flow model of Cauchy–Poisson type for the transient fluid motion forced by seabed deformation. Our new model advances previous studies, where simplified formulae without direct forcing were assumed for the wave field. Using complex integration and large-time asymptotics, we obtain a novel analytical solution for the magnetic field propagating at large distance from the seabed deformation in two dimensions. We show that this magnetic field is made of two terms, one proportional to an Airy function, and thus propagating similarly to the surface gravity wave, and one proportional to a Scorer function, which exhibits a phase lag with respect to the surface gravity wave. Such a phase lag explains the time difference between the arrival of the EM field and the surface gravity wave generated by seabed deformation, which were observed in recent measurements and numerical results. Finally, we discuss the opportunity to detect EM fields as precursors of surface gravity waves in tsunami early warning systems. We introduce a novel non-dimensional parameter to identify the propagation regime of the magnetic field, i.e. self-induction versus diffusion-dominated. We show that tsunami early warning via EM field is possible for diffusion-dominated regimes when the water depth is less than 2 km. Our findings provide a rigorous analytical explanation of existing observations and numerical results.

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“…In this work, the initial sea surface displacements for hypothetical 7.0 and 8.0 Mw earthquakes along the Cocos Plate with epicenters at 16.9718°N–101.973°W, ~86 km from Zihuatanejo (near the epicenter of the April 18, 2014 earthquake 7.2 Mw, the last hardest submarine earthquake near Zihuatanejo [Servicio Sismológico Nacional; SSN, 2020]), were calculated using the Okada (1985) formulae with the okada85 function (Beaudecel, 2019) for a fault plane with a depth, strike, dip, and rake of 20 km, 300°, 14°, and 100°, respectively (Figures 5 and 6), values similar to those reported by the Harvard Centroid‐Moment‐Tensor Project catalog (CMT, 2020) for the September 19, 1985 earthquake 8.1 Mw. The fault length, width and average slip were calculated via the earthquake moment magnitude (Levin & Nosov, 2016), assuming incompressibility of water, and considering the initial water surface elevation from the mean sea level to be equivalent to the seabed displacement field induced by the slip on the fault plane. The movement of the seafloor was considered to be instantaneous, and the water surface followed the changes to the seafloor (Wang, 2009).…”

Section: Model For Simulating Tsunami Generation and Floodingmentioning

confidence: 99%

Tsunami run‐up along the Zihuatanejo region, Mexican Pacific Coast: A modelling study

Contreras‐Tereza

Salas‐de‐León

Monreal‐Jiménez

et al. 2020

J Flood Risk Management

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A numerical hydrodynamic model was applied to Zihuatanejo Bay on the Mexican Coast of the Pacific Ocean to study the heights and arrival times of tsunamis produced by hypothetical 7.0 and 8.0 Mw magnitude earthquakes with epicenter in the Cocos Plate, at 16.9718°N–101.973°W, as well as the flooding of Zihuatanejo Town by the tsunamis. The travel times of the tsunamis to Zihuatanejo Coast are between 18 and 19 min, maximum sea surface elevations of 1 and 10 m at the coast are estimated following a 7.0 and 8.0 Mw earthquake respectively with a tsunami inland penetration up to 400 m in the second case affecting restaurants, hotels, banks, schools, businesses, museums, and even the municipal market of the town. Therefore, a densely populated area would be affected by a tsunami triggered by an 8.0 Mw earthquake.

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Source of a Tsunami of Seismotectonic Origin

Cited by 5 publications

References 57 publications

Two-way coupled long-wave isentropic ocean-atmosphere dynamics

Two-way coupled long-wave isentropic ocean-atmosphere dynamics

Electromagnetic field generated by tsunamigenic seabed deformation

Tsunami run‐up along the Zihuatanejo region, Mexican Pacific Coast: A modelling study

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