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The Hunga Tonga–Hunga Ha'apai volcanic eruption on January 15, 2022 generated a tsunami that affected the entire Pacific Ocean. Tsunami waves from the event have been generated both by incoming waves from the source area with a long-wave speed in the ocean of ~200–220 m/s, and by an atmospheric wave propagating at a sound speed of ~315 m/s. Such a dual source mechanism created a serious problem and was a real challenge for the Pacific tsunami warning services. The work of the Russian Tsunami Warning Service (Yuzhno-Sakhalinsk) during this event is considered in detail. The tsunami was clearly recorded on the coasts of the Northwest Pacific and in the adjacent marginal seas, including the Sea of Japan, the Sea of Okhotsk, and the Bering Sea. We examined high-resolution records (1-min sampling) of 20 tide gauges and 8 air pressure stations in this region for the period of January 14–17, 2022. On the Russian coast, the highest waves, with a trough-to-crest wave height of 1.3 m, were recorded at Malokurilskoe (Shikotan Island) and Vodopadnaya (southeastern coast of Kamchatka). Using numerical simulation and data analysis methods, we were able to separate oceanic "gravity" tsunami waves from propagating atmospheric pressure waves. In general, we found that on the outer (oceanic) coasts and southern coast of the Sea of Okhotsk, oceanic tsunami waves prevailed, while on the coast of the Sea of Japan, oceanic and atmospheric tsunami waves had similar heights. [ABSTRACT FROM AUTHOR]

The explosive eruption of the Hunga Tonga-Hunga Ha'apai volcano on 15 January 2022 generated atmospheric waves traveling around the Earth, which caused ionospheric disturbances on various spatio-temporal scales. A HF Doppler sounding system in Japan detected characteristic ionospheric disturbances showing periodic oscillations in the Doppler frequency with a period of ~ 4 min. In this study, such periodic oscillations were examined by comparing Doppler frequency data with Total Electron Content data obtained by Global Navigation Satellite System. The observed periodic oscillations in the Doppler frequency were characterized by a sawtooth or S-letter shaped variation, implying the passage of the traveling ionospheric disturbances through the reflection points of the HF Doppler sounding system. It was also found that the periodic oscillations occurred prior to the arrival of the tropospheric Lamb wave excited by the Tonga eruption. From the total electron content data, the traveling ionospheric disturbances causing the periodic oscillations were excited by the tropospheric Lamb waves at the conjugate point in the southern hemisphere, namely, the electric field perturbations due to the Lamb waves in the southern hemisphere mapped onto the sensing area of the HF Doppler sounding system in the northern hemisphere along the magnetic field lines. The periodic oscillations were observed only in the path between Chofu transmitter and Sarobetsu receiver, whose the radio propagation path is almost aligned in the north–south direction. This suggests that the traveling ionospheric disturbance has a structure elongating in the meridional direction. The variation in the Doppler frequency was reproduced by using a simple model of the propagation of the traveling ionospheric disturbances and the resultant motion of the reflection point. As a result, the vertical motion of the reflection point associated with the periodic oscillations was estimated to be about 1 km. It is known that 4-min period variations are sometimes observed in association with earthquakes, which is due to resonances of acoustic mode waves propagating between the ground and the lower ionosphere. Therefore, a similar resonance structure in the southern hemisphere is a plausible source of the traveling ionospheric disturbances detected in the northern hemisphere. [ABSTRACT FROM AUTHOR]

Based on the barometric data recorded by the seismic monitoring network on the Chinese mainland, Lamb wave periods and relative arrival times of 462 stations are obtained with the aid of Meyer's wavelet decomposition, Welch's periodogram spectrum estimation and waveform cross-correlation. By extracting the seismic Rayleigh waves of two seismic stations in the South Pacific and comparing them with the synthetic seismograms, the occurrence time of the first two large volcanic eruptions and the largest volcanic eruption are credibly deduced, and then the travel times and propagation speeds of the Lamb waves are obtained. In order to further explain the attributes of the pressure disturbance associated with the complex acoustic gravity wave (AGW) phases on pressure, a series of numerical simulations with the QSSP program are applied to yield highly similar waves corresponding to the barometric records, which indicates that the eruption source may contain more than 10 sub-events within an hour. According to our detailed analyses, major conclusions are obtained as follows: (1) Although the primary pressure disturbance of the Tonga volcanic eruption appears to be a simple bulge, it is in fact a complex wave composed of multiple eruptions. The largest eruption occurred about 13 min after the first large eruption. (2) In addition to the propagation of the traditional Lamb mode, the Pekeris mode phase that propagates with a lower speed is also observed in some stations, and its amplitude is about a fifth of the Lamb wave. The Pekeris waves may have been more significantly delayed as they traveled against the westerly wind due to their much shorter periods and lower velocities. (3) The group velocity of the Lamb wave is about 308 m/s. Its average period is 70 min, and the wavelength is about 1300 km. The arrival time deviation at each station is negatively correlated with the difference in the near-surface air temperature between North and South China. However, accurately estimating the parameters of the Pekeris waves or the antipodal Lamb waves is challenging due to their low signal-to-noise ratio (SNR), even though the horizontal propagation speed of the Pekeris wave toward China is estimated to be approximately 225 m/s. (4) Much shorter periods and later arrivals at the stations within 200 km of Beijing may be related to the significant cooling (i.e. 12 °C temperature drop), which occurred from Ulantoba, Outer Mongolia, to Beijing beginning at noon on January 15 (Beijing time). [ABSTRACT FROM AUTHOR]

Abstract—The possibility of remote studying the electromagnetic and ionospheric effects of the eruption of the Tonga volcano on January 15, 2022 is demonstrated. At distances up to 15000 km from the source, geomagnetic variations associated with Schuman resonance (SR) perturbations, propagation of Lamb wave and acoustic-gravity waves were detected. It is shown that the formation of a high-power source of thunderstorm activity caused by the eruption resulted in a significant (more than threefold) increase in the amplitude of geomagnetic disturbances at SR frequencies, which correlates with the number of lightning events. The effect of the eruption on the frequency characteristics of the SR was not detected. [ABSTRACT FROM AUTHOR]

On 15 January 2022, the Hunga Tonga-Hunga Ha'apai (HTHH) (175.38° W, 20.54° S) volcano erupted explosively. It is considered the most explosive volcanic eruption during the past 140 years. The HTHH volcanic eruption caused intense ripples, Lamb waves, and gravity waves in the atmosphere which encircled the globe several times, as reported by different studies. In this study, using OMI, SAGE-III/ISS, and CALIPSO satellite observations, we investigated the spread of the volcanic SO2 cloud due to the HTHH eruption and subsequent formation of sulfuric acid clouds in the stratosphere. It took about 19–21 days for the stratospheric SO2 injections of the HTHH to encircle the globe longitudinally due to a dominant westward jet with wind speeds of ~2500 km/day, and it slowly dispersed over the whole globe within several months due to poleward spread. The formation of sulfuric acid clouds intensified after about a month, causing the more frequent occurrence of high aerosol optical depth elevated layers in the stratosphere at an altitude of about 20–26 km. This study deals with the dynamics of volcanic plume spread in the stratosphere, knowledge of which is essential in estimating the accurate radiative effects caused by perturbations in the earth–atmosphere system due to a volcanic eruption. In addition, this knowledge provides important input for studies related to the geo-engineering of the earth's atmosphere by injecting particulates and gases into the stratosphere. [ABSTRACT FROM AUTHOR]

The manifestations of the Hunga Tonga–Hunga Haʻapai volcano explosive eruption on January 15, 2022, in the Pacific region were investigated using the data of the DART deep ocean sea level stations and the IRIS ground-based barographs. It was found that the atmospheric Lamb wave, caused by the explosion of the volcano, was formed at 04:27 UTC ± 4 min and propagated over the Pacific Ocean at a speed of 312 ± 4 m/s. It is shown that the leading distinct pulse recorded by all DART deep ocean sea level stations is a direct manifestation of the atmospheric Lamb wave. Theoretical estimations of the amplitude manifestations of the Lamb wave in the bottom pressure variations have been made. It is shown that the amplitude of bottom pressure variations in the deep ocean is a few times larger than the amplitude of pressure variations in the Lamb wave. Theoretical estimates of the amplitude of surface gravity waves excited in the ocean by traveling atmospheric disturbance passing a depth jump are carried out. [ABSTRACT FROM AUTHOR]

On 15 January 2022, Tonga's Hunga Tonga‐Hunga Ha'apai (HTHH) volcano violently erupted, generating a tsunami that killed three people. Acoustic‐gravity waves propagated by the eruption and tsunami caused global complex ionospheric disturbances. In this paper, we study the nature of these perturbations from Global Navigation Satellite System observables over the southwestern Pacific. After processing data from 818 ground stations, we detect supersonic acoustic waves, Lamb waves, and tsunamis, with filtered magnitudes between 1 and 7 Total Electron Content units. Phase arrivals appear superpositioned up to ∼1,000 km from HTHH and are distinct by ∼2,200 km. Within ∼2,200 km, signals have an initial low‐frequency pulse that transitions to higher frequencies. We note the presence of a faster perturbation generated 1 hr post‐eruption which crosses the tsunami disturbance ∼3,000 km from HTHH, potentially contributing to premature land arrivals. Lastly, the arrival of tsunami‐generated disturbances coincides with deep‐ocean observations. Plain Language Summary: The 15 January 2022 volcanic eruption of Hunga Tonga‐Hunga Ha'apai and subsequent tsunamis sent powerful energy waves into the ionosphere (a layer of Earth's atmosphere that is deformed by energy emitted from events like volcanic eruptions, tsunamis, earthquakes, tornadoes, hurricanes, and large man‐made explosions). These waves can provide valuable information about different phases of the event, such as the powerful explosion, sound wave, and tsunami. Using Global Positioning Systems data, we measure these ionospheric signals over the southwestern Pacific Ocean to examine which phases of the event contributed to each ionospheric disturbance. We successfully detect all three event phases in the ionosphere and determine the distance at which these signals separate from one another. Furthermore, we validate our data by comparing tsunami signals in the ionosphere against direct ocean‐based observations of tsunami activity. Of particular note is our observation of a faster ionospheric signal that forms an hour after the eruption and catches up to the tsunami's disturbance. Our work supports the hypothesis that others have proposed in which high‐energy waves from the eruption escalated tsunami speeds and wave heights. This, in turn, supports the observation of early tsunami arrivals that were reported along many Pacific coastlines. Key Points: We see distinct phase arrivals in the ionosphere for a supersonic wave, Lamb wave, and tsunami (the latter is validated by ocean sensors)Phase arrivals begin to separate at ∼1,000 km from Tonga and are fully separated by ∼2,200 kmWe highlight a faster disturbance that propagates 1 hr post‐eruption and meets the tsunami perturbation ∼3,000 km from the volcano [ABSTRACT FROM AUTHOR]

The eruption of Hunga-Tonga Volcano on January 15, 2022 has stimulated a wide spectrum of atmospheric waves globally. To probe the surface deformation pattern, Sentinel-1 Synthetic Aperture Radar (SAR) data has been analyzed. It has been approximated that an overall area of about 2.47 square kilometres experienced deformation in conjunction with this event. To characterize the atmospheric wave propagation, barometric pressure data from 1814 stations distributed all around the globe have been examined. This study encompassed with the propagation characteristics of the waves over four zones including Indian and Polar regions for the first time using barometric data. Time-series observations indicate that the waves propagated globally multiple times. Within the Indian region, three minor arc passages and one major arc passage were identified. In Japan, two minor arc passages and one major arc were present. Conversely, in North America, both minor and major arc passages were detected, occurring a minimum of three times. Moreover, the attributes of these waves, such as their propagation speed and periodicity, were compared across these four regions. The estimated phase speed and periodicity fall within the ranges of approximately 291–314 m/s and 10–180 min, respectively including Polar Regions. These speed and periodicity measurements of the observed waves suggest that the dominant mode of wave propagation generated during the Tonga volcanic eruption is that of Lamb waves. In addition, a slower propagation phase speed of about 226.6 m/s was identified in Japan which corresponds to Pekeris mode of waves. • Hunga-Tonga volcanic eruption triggered atmospheric waves that travelled globally in all direction multiple times. • Analysis of barometric data from India, Japan, North America and Polar Regions reveal the multi-wave characteristics of atmospheric waves. • The comparison of phase speed and periodicities are in the range ∼291–314 m/s and 45–50 min respectively. [ABSTRACT FROM AUTHOR]

The Lamb waves caused by the explosive phase of the eruption of the Hunga-Tonga-Hunga-Ha'apai Volcano located on the island of the same name, circled the globe several times, exciting the same disturbances on their way in the Earth's crust and oceans. They were recorded at Cape Schultz with a laser nanobarograph, and the induced deformation perturbations were recorded with a laser strainmeter. The first 2 gPa disturbance was recorded 7 h 50 min after the volcanic eruption. [ABSTRACT FROM AUTHOR]

Tide gauge data indicated that ocean waves were generated by the eruption of the Hunga Tonga-Hunga Ha'apai volcano on January 15, 2022. These high-amplitude waves reached the Japanese coast earlier than expected for free ocean waves. These fluctuations in sea level were reasonably reproduced by an ocean model, with realistic bottom topography forced by sea-level pressure perturbations well reproduced by atmospheric general circulation models. While early arrival times are associated with atmospheric Lamb waves, the amplitude of the sea level changes cannot be fully explained by the resonance mechanism associated with sea-level pressure fluctuations of Lamb and Pekeris waves alone. Rather, resonance due to atmospheric waves in conjunction with the amplification effects caused by a steep continental slope is required in order to reproduce sea level fluctuations along the Japanese coast. In particular, the deep Northwest Pacific Basin to the east of Japan is important for strengthening the amplitude of the meteorological tsunami. • Sea level fluctuations due to the 2022 volcanic eruption in Tonga was reproduced. • Meteorological tsunamis were generated by Lamb and Pekeris waves. • Meteorological tsunamis by Pekeris waves are amplified due to Proudman resonance. • Meteorological tsunamis are amplified by entering the sharp continental slope. [ABSTRACT FROM AUTHOR]