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The Hunga‐Tonga volcano eruption on 15 January 2022 generated tsunami waves that impacted both the Pacific and Atlantic coasts of the Americas. A unique feature of this event was the dual tsunami generation mechanism, which led to motions with long (several days) ringing and slow energy decay. The first ocean waves to reach the coast were "atmospheric tsunamis" generated by atmospheric Lamb waves that propagated with the speed of sound (∼314 m/s) and circled the globe in both directions several times before being fully attenuated. The second type of ocean waves were classical "oceanic tsunami" waves forced directly by the volcanic eruption and which propagated across the Pacific at roughly 2/3 the speed of the atmospheric waves. This study focuses on time series of the Hunga‐Tonga event recorded by tide gauges, microbarographs and Deep‐ocean Assessment and Reporting of Tsunamis on and off the Pacific coasts of North and Central America and in the Gulf of Mexico. Atmospheric tsunami waves only were recorded in the Gulf of Mexico, where the sea level response to the second, westward (shoreward) propagating atmospheric wave was stronger than to the first, eastward (seaward) propagating wave. Along the Pacific coast, the atmospheric tsunami waves were approximately 3–4 times smaller than the oceanic tsunami waves, which at several Mexican stations exceeded 2 m in height. The broad frequency range of 0.2–0.25 to 30 cph spanned by the oceanic tsunami in the Pacific indicates that the "effective" source area for the oceanic waves was more extensive than initially proposed. Plain Language Summary: The eruption of the Hunga‐Tonga volcano in January 2022 generated two types of tsunami waves: ordinary "oceanic" tsunami waves forced by the eruption itself and "atmospheric" tsunami waves forced by propagating pressure waves in the atmosphere. The oceanic tsunamis radiated outward into the Pacific while the atmospheric waves propagated around the globe several times in both the eastward and westward directions. Measurements by tide gauges, microbarographs and open‐ocean Deep‐ocean Assessment and Reporting of Tsunamis stations on and off the Pacific coasts of North and Central America and the Gulf of Mexico show that both types of waves were recorded on the Pacific coast but that only the atmospherically generated waves were recorded in the Atlantic Ocean and adjoining Gulf of Mexico. The atmospheric tsunamis were 3–4 times smaller than the oceanic tsunamis, which at Port San Luis and several Mexican locations, including Manzanillo and Ensenada, were higher than 2 m. The broad frequency content of the oceanic waves indicates that their source region had an "effective" area that greatly exceeded that directly spanned by the volcanic eruption. Key Points: The Tonga volcanic event generated two types of tsunami waves: "oceanic" by the eruption and "atmospheric" by atmospheric Lamb wavesThe open‐ocean and coastal records enabled us to separate the two types of tsunami waves and determine their physical propertiesThe waves span a wide frequency range, indicating that the "effective" source region greatly exceeded that covered by the eruption [ABSTRACT FROM AUTHOR]

The dual frequency Global Navigation Satellite System (GNSS) observations could determine the total electron content (TEC) in the ionosphere. In this study, GNSS TEC was applied to detect traveling ionospheric disturbances (TIDs) after the eruption of Hunga Tonga–Hunga Ha'apai (HTHH) on 15 January 2022. The eruption caused two types of tsunamis, first is tsunami generated by atmospheric wave (meteo‐tsunami) and second is caused by eruption induces water displacement or tsunami classic. At the same time with former tsunami, the atmospheric wave (shock and lamb waves) also caused TIDs at a speed of approximately ∼0.3 km/s. We found moderate correlation between this TIDs amplitude and the tsunami wave height model from tide gauge stations in New Zealand (0.64) and Australia (0.65). Further we attempted to reveal 3D structure of the TIDs in New Zealand, South Australia, and Philippines using 3D tomography. The tomography was set up > 1,170 blocks, as large as 1.0° (east–west) × 1.0° (north–south) × 100 km (vertical), up to 600 km altitude over selected regions. Tomogram shows beautiful concentric directivity of the first TIDs generated by atmospheric wave (AW). Key Points: 3D ionospheric disturbances during the 2022 Tonga eruption was investigated with spatial and temporal directionThe highest concentration of the electron disturbances was observed at an altitude of 200–300 km, which decreased at 500–600 kmA correlation between ionospheric disturbances and the height of tsunami associated with eruption was observed [ABSTRACT FROM AUTHOR]

In 2022, the Hunga volcano eruption in Tonga generated atmospheric pressure waves that propagated globally and produced tsunamis in all the world's oceans. The largest pressure wave, with an amplitude of several hundred pascals, is the Lamb wave. Standard Lamb wave models, incorporating the sound‐speed as a function of temperature, satisfactorily explain observations in the near‐field but not in the far‐field. We show that an augmented Lamb wave model that includes the effects of wind and topography accurately reproduces the wavefronts observed by satellites and barometers, including those close to the antipode. Winds, first suggested to explain the travel times of Lamb waves from Krakatau in 1883, are now shown to also play a major role in shaping their waveforms; temperature and topography play smaller, but still detectable, roles. Our augmented model provides a significant advance for the development of early warning and hazard assessments for the meteotsunamis these waves produce. Plain Language Summary: The January 2022 explosive eruption of the Hunga volcano in Tonga produced a pressure wave (of a type known as a Lamb wave) in the atmosphere, which was detected worldwide. This wave circled the Earth more than once, and generated tsunami in unexpected times and places. We have derived a mathematical description that allows us to quickly and accurately model the observations of this atmospheric wave. The description includes the effects of winds, temperature, and topography. The wave modeled using this description reproduces satellite and ground observations much better than simpler models, notably the complex pattern of the wave near the antipode of the eruption. Our model clearly identifies global winds as the crucial influence on global‐scale Lamb‐wave propagation, and provides modeling tools for possible future occurrences of such waves and the global tsunamis created by them. Key Points: A augmented model is proposed to simulate the propagation of planetary scale Lamb waves, incorporating wind, temperature and topographyWinds play a primary role shaping Lamb waves in the far field, especially near the antipode of the sourceThe augmented Lamb wave model will help better assess far‐field volcanic tsunami hazards [ABSTRACT FROM AUTHOR]

We investigate the oceanic and ionospheric response in New Caledonia‐New Zealand and Chile‐Argentina to the 15 January 2022 Hunga‐Tonga volcanic eruption. For the first time, we highlight a reversed response in the oceans and in the ionosphere in terms of the amplitudes. The sea‐surface fluctuations due to the passage of the atmospheric Lamb wave (i.e., air‐sea wave) were not remarkable while the related ionospheric perturbation was considerable. Reversely, the eruption‐induced tsunami ("regular" tsunami) caused major variations in sea‐surface heights (∼1 m near the volcano and ∼2 m along the Chilean coastline), whereas the associated ionospheric perturbation was quite small. The observed large‐amplitude ionospheric response due to Lamb waves propagation is difficult to explain, and the coupling between the Lamb wave and the ionosphere is not well‐understood yet. For the first time, we estimate the delay between the Lamb waves and their signatures in the ionosphere to be ∼12–20 min. Plain Language Summary: The eruption of Hunga‐Tonga volcano produced a variety of atmospheric and tsunami waves recorded all over the world. We study the impacts of the eruption together on the oceans and in the ionosphere in New Caledonia‐New Zealand (near the volcano) and Chile‐Argentina (far from the volcano). At the sea surface, we observe two phenomena causing sea‐height variations. The first is a small tsunami (air‐sea wave) created by the Lamb wave: the high‐pressure atmospheric wave triggered by the eruption. The second is the tsunami induced by the eruption itself. Spectacularly, at 300 km altitude, in the ionosphere, we observe perturbations in the electron content caused by the Lamb wave and by the regular tsunami. We are the first to report on the reversed amplitude of the two phenomena in the oceans and in the ionosphere. The sea‐surface perturbation caused by the Lamb wave was not significant, while ionospheric perturbation was considerable. In contrast, the regular tsunami wave produced major variations. For the first time, we estimate the time delay between the Lamb wave and its signature in the ionosphere. Key Points: Joint study of oceanic and ionospheric response in New Caledonia‐New Zealand and Chile‐Argentina to the 15 January 2022 volcanic eruptionNear‐surface propagating Lamb wave caused a small tsunami in the ocean (air‐sea wave) and unusually strong disturbances in the ionosphereInversely, the eruption‐generated tsunami showed significant wave heights in the ocean and much smaller response in the ionosphere [ABSTRACT FROM AUTHOR]

On 15 January 2022, around 4:30 UTC the eruption of the Hunga‐Tonga volcano, in the South Pacific Ocean, generated a violent underwater explosion. In addition to tsunami waves that affected the Pacific coasts, the eruption created atmospheric pressure disturbances that spread out in the form of Lamb waves. The associated atmospheric pressure oscillations were detected in high‐frequency in‐situ observations all over the globe. Here we take advantage of the similarities in the propagation and characteristics between atmospheric Lamb waves and long ocean waves and we use a 2DH ocean numerical model to simulate the phenomenon. We compare the outputs of the numerical simulation with in‐situ atmospheric pressure records and with remote satellite observations. The signal in the model matches the observed atmospheric pressure perturbations and reveals an excellent agreement in the wave arrival time between model and observations at hundreds of locations at different distances from the origin. Plain Language Summary: The underwater explosion of the Hunga‐Tonga volcano in the South Pacific Ocean generated atmospheric pressure disturbances, known as Lamb waves, that propagated and surrounded the globe several times. In this study, we exploit the similarities between atmospheric Lamb waves and long waves in the ocean (e.g., tsunamis) to simulate their propagation using an ocean numerical model. The comparison of our results with remote satellite data and in‐situ atmospheric pressure records reveals that our model correctly reproduces the propagation of the atmospheric disturbances generated by the volcano explosion. Key Points: The underwater Hunga‐Tonga volcano exploded generating Lamb waves that traveled around the Earth several timesWe simulate these waves using a hydrostatic shallow water equation oceanic modelThe results closely follow the observations of atmospheric pressure perturbations [ABSTRACT FROM AUTHOR]