ITS3.6/SM1.2

Late-breaking session: The 15 January 2022 Hunga Tonga Volcanic Eruption – Observation, Understanding and Impact of large explosive volcanic eruptions

The 2021-2022 Hunga Tonga-Hunga Ha'apai eruption in Tonga was among the largest of recent decades. The event was notable for its high intensity, generating a convective column that rapidly ascended well into the stratosphere; for the atmospheric pressure wave generated by the explosion, which was detected globally; and for generating a tsunami that was observable across Pacific Ocean shorelines. Following a series of preceding seismic and explosive events since December 2021, the sustained phase of the eruption on 15th January was relatively short lived, but the associated pressure wave and tsunami impacts were the most far-reaching since the eruption of Krakatau volcano in 1883. Tsunamis were recorded both locally and in the far-field, but their mechanism(s) remains uncertain; in the near field being from either (or both of) the collapsing eruption column or a phreatomagmatic explosion as the erupting mass mixed with sea water. In the far-field the tsunamis are possibly best explained by the massive atmospheric pressure wave, that is the first instrumentally recorded eruption-generated event of its type, which affected the entire global atmosphere and ionosphere, causing the observed infrasound waves and unusual long-period seismic resonances.
This interdisciplinary late-breaking session welcomes contributions from all disciplines involved in local and global observations of this eruption and its effects, including remote sensing observations and modeling as well as hazard assessment and estimation of damage and long-term consequences.

Co-organized by AS4/GMPV10/NH/OS4
Convener: Torsten Dahm | Co-conveners: Hélène Hébert, David Tappin, Elvira Astafyeva, Sebastian Watt
Presentations
| Thu, 26 May, 08:30–11:47 (CEST)
 
Room N1

Presentations: Thu, 26 May | Room N1

Chairpersons: Elvira Astafyeva, Sebastian Watt, Torsten Dahm
08:30–08:40
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EGU22-13584
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solicited
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Highlight
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Virtual presentation
Shane Cronin, Marco Brenna, Taaniela Kula, Ingrid Ukstins, David Adams, Jie Wu, Joa Paredes Marino, Geoff Kilgour, Graham Leonard, James White, Simon Barker, and Darren Gravley

The phreatoplinan eruption of the shallow submarine Hunga Volcano Tonga formed global air-pressure waves, regional tsunami and an up to 55 km-high eruption column. Despite its large explosive magnitude, the magma erupted were similar to past compositions, and comprised crystal poor (<8 wt% total; plag>cpx>opx) andesite with ~57-63 wt% silica glass. Low magnitude Surtseyan eruptions in 2009-2015 formed from small pockets of andesite that ascended slowly, resulting in high microphenocryst and microlite contents. Large eruptions, including events in ~AD200 and AD1100 and the 2022 event drew magma rapidly from a ~5-7 km deep mid-crustal reservoir. Rapid decompression and quenching (augmented by magma-water interaction) records the heterogeneity of the reservoir, with mingled glass textures and cryptic mixing of subtly different melts. The 2022 feldspar phenocrysts show more mafic melt inclusion compositions than host glass, clear uniform cores and thin rims evidencing ~1 month-long changes caused by decompression, rise and internal mingling of subtlety different melts. CPX phenocrysts show uniform cores a variety of more mafic and similar melt inclusions to the bulk glass, and thin overgrowth rims reflecting only decompression and mingling. Lithic fragments (<8wt%) include common hydrothermal minerals (sulphides, quartz etc). Without evidence of a mafic trigger, or crystalisation induced overpressures, this extremely violent eruption was triggered by top-down processes that led to rapid exhumation/decompression of magma and very efficient explosive magma-water interaction. This could include any, or all of: flank collapse; hydrothermal seal fracturing and ingress of water into the upper magma system and caldera collapse. Subsequent earthquakes suggest that the crustal magma system was rapidly recharged in the days following the eruption.

How to cite: Cronin, S., Brenna, M., Kula, T., Ukstins, I., Adams, D., Wu, J., Paredes Marino, J., Kilgour, G., Leonard, G., White, J., Barker, S., and Gravley, D.: The 15 January 2022 Hunga eruption, Tonga – first petrographic and geochemical results, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13584, https://doi.org/10.5194/egusphere-egu22-13584, 2022.

08:40–08:47
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EGU22-13585
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Virtual presentation
Ingrid Ukstins, Shane Cronin, David Adams, Jie Wu, Joali Paredes Marino, Marco Brenna, Ian Smith, and Isabelle Brooks-Clarke

The 15 Jan 2022 eruption of Hunga-Tonga-Hunga-Ha’apai was the largest explosive volcanic event in the last 30 years. These islands represent the subaerially exposed summit of the Hunga Volcano, merged into a single land mass during the most recent eruption in 2014-2015. The 2022 eruption likely represents a 1-in-1000-year event for the Hunga Volcano, with the previous large-magnitude eruption occurring in ~1100 CE during a series of caldera-forming events. The 2022 erupted magma is plagioclase-, orthopyroxene- and clinopyroxene-bearing basaltic andesite to andesite dominated by blocky, poorly vesicular glassy ash with lesser amounts of vesicular pumiceous ash and fine lapilli. Melt Inclusions (MIs) hosted in plagioclase, clinopyroxene and orthopyroxene are abundant and glassy, some displaying shrinkage bubbles, with no evidence of secondary crystallization along the walls or within the MI glass. The groundmass glass and MI in the three main phenocryst phases were analysed for major, trace and volatile element concentrations to enable identification of magmatic sources and to better constrain processes happening at depth. Preliminary data indicate that plagioclase phenocrysts range from An93 to An78, and MI range from 54.1 to 58.7 wt % SiO2, with MgO from 2.5 to 5.3 wt %. Clinopyroxene phenocrysts range from En42 to En50, and MI range from 51.6 to 65.1 wt % SiO2, with MgO from 1.1 to 5.7 wt %. Orthopyroxene phenocrysts range from En68 to En77, and MI range from 55.7 to 59.6 wt % SiO2, with MgO from 2.5 to 5.3 wt %. Clinopyroxene MI span the full range of SiO2 compositions observed from the Hunga Volcano, from the host 2022 event (SiO2: ~57.5 wt %), the 1100 CE event (SiO2: ~60 wt %), the 2014-2015 event (SiO2: ~60.5 wt %), and the most evolved 2009 event (SiO2: ~63 wt %) and extend an additional ~4 wt % SiO2 to more mafic compositions. Orthopyroxene MI most closely resemble the 1100 CE event and the average groundmass glass compositions of the 2022 event. Plagioclase MI overlap the least silicic compositions observed in the 2022 groundmass glass (58.6 wt% SiO2) and extend down to 54 wt % SiO2, overlapping the main field of clinopyroxene MI. Both plagioclase and clinopyroxene MI tend to show higher MgO as compared to the 2022 groundmass glass at the same SiO2 concentration, whereas orthopyroxene shows lower MgO than the groundmass glass. SO3 in MI ranges up to 1600 ppm, significantly higher than the 2022 groundmass glass which averages 200 ppm, with both plagioclase and clinopyroxene MI preserving the highest observed concentrations. In contrast, Cl concentrations in MI extend to 2000 ppm, with the highest values in orthopyroxene and clinopyroxene, and plagioclase MI are lower and generally overlie the main groundmass glass concentrations (~1300 ppm). F was below detection limits. We postulate that clinopyroxene crystals reflect a more primitive basaltic andesite magma, whereas orthopyroxene crystals were likely derived from the magmatic remnants of the 2009 and 2014/2015 events in the upper magma system, and plagioclase crystals were sourced from the full range of magma sources.

How to cite: Ukstins, I., Cronin, S., Adams, D., Wu, J., Paredes Marino, J., Brenna, M., Smith, I., and Brooks-Clarke, I.: Hunga-Tonga-Hunga-Ha’apai Jan 15, 2022 eruption: Assembly of heterogeneous magma sources recorded in melt inclusions from plagioclase, clinopyroxene and orthopyroxene., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13585, https://doi.org/10.5194/egusphere-egu22-13585, 2022.

08:47–08:54
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EGU22-13587
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Virtual presentation
Joali Paredes-Mariño, James White, Tobias Dürig, Rachel Baxter, Taaniela Kula, Shane Cronin, Ingrid Ukstins, Jie Wu, David Adams, Marco Brenna, and Isabelle Brooks-Clarke

The January 2022 eruption of Hunga Volcano, Tonga is likely the most explosive mafic eruption yet documented. It exhibited dynamics of ash plume expansion and atmospheric pressure waves unlike anything seen before. This is remarkable considering that it erupted crystal-poor and microlite-poor andesitic magma (57-63 wt% silica glass). The climactic phase produced an eruptive column of at least 39 km in height, however, the ash volume appears anomalously small for the explosive magnitude. Ash from nine different sites across the Kingdom of Tonga were analyzed for textural and morphological properties and grain size distribution. The tephra comprises light pumice (16%), dark pumice (44%), glassy microlite-rich grains (25%), lithics (7%) and free-crystals (Pl, Cpx, Opx) (8%). Specific gravity of particles range from 0.4 to ~2.5. Secondary electron images show that pumices have a variable vesicularity, from dense glassy blocky particles; glassy particles with isolated vesicles and weakly deformed, thick vesicle walls; and a smaller percentage of microvesicular pumices, coated in finer particles. The general characteristics imply a rapid decompression, fragmentation and chilling. This implies some form of phreatomagmatism but with high-efficiency to generate such a large blast – e.g., via propagation of stress waves and thermal contraction rapidly increasing a magma surface area for interaction. The ash is fine-grained and poorly sorted overall. Less than 20 wt.% of ash particles are >1 mm at 80 km SE of the volcano on the main island of Tongatapu, while 70 km NE of the volcano (Nomuka Island) has finer ash, with only 2% of particles >1 mm. It appears that the dispersion axis for the event was directed toward the E or ESE, across the main population centre of Nuku’alofa on Tongatapu. Of the fine fraction 20 wt.% is < 30 micron, 8 wt.% <10 micron but unusually few particles of very fine range (<0.05 wt.% finer than 1 micron). Variations in the mode and sorting of ash fall at different locations and angles from the vent show that there was potentially complex dispersal of ash from different phases of the 11-hour long eruption, and or different plume heights and fragmentation processes involved. Plume observations suggest at least two different plume levels during main phases of the eruption and the fragmentation mechanisms likely varied from the blast-generating phase and the lesser-explosive phases leading up to and following this.

How to cite: Paredes-Mariño, J., White, J., Dürig, T., Baxter, R., Kula, T., Cronin, S., Ukstins, I., Wu, J., Adams, D., Brenna, M., and Brooks-Clarke, I.: Understanding fragmentation mechanism(s) during the 15 January 2022 Hunga Volcano (Tonga) eruption through particle characteristics, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13587, https://doi.org/10.5194/egusphere-egu22-13587, 2022.

08:54–09:01
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EGU22-13586
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ECS
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Highlight
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Virtual presentation
Sönke Stern, Shane Cronin, Marta Ribo, Simon Barker, Marco Brenna, Ian E. M. Smith, Murray Ford, Taaniela Kula, and Rennie Vaiomounga

In December 2014, eruptions began from a submarine vent between the islands of Hunga Tonga and Hunga Ha’apai, 65 km north of Tongatapu, Tonga. The “Hungas” represent small NW and NE remnants of the flanks of a larger edifice, with a ~5 km-diameter collapse caldera south of them. The 2014/15 Surtseyan explosive eruptions lasted for 5 weeks, building a 140 m-high tuff ring.

Deposits on Hunga Ha’apai and tephra fall on Tongatapu record two very large magnitude eruptions producing local pyroclastic density currents and tephra falls of >10 cm-thick >65 km away. These likely derive from the central edifice/caldera. The 2022 eruption produced slightly less tephra fall, but an extremely large explosive event, with regional tsunami indicating substantive topographic change.

Here we report the bathymetric details of the caldera as of November 2015. A multibeam sounder (WASSP) was used to mapping the shallow (<250 m) seafloor concentrating on the edges of the Hunga caldera. These results were combined with an aerial survey of the 2015 tuff cone, using a combination of drone photogrammetry and real-time kinematic GPS surveys. The bathymetry reveals that previous historical eruptions, including 1988 and 2009, and likely many other recent unknown produced a series of well-preserved cones around the rim of the caldera. Aside from the raised ground in the northern caldera produced by the 2009 and 2014/15 eruptions, the southern portion is also elevated to within a few m below sea level, with reefs present. During the 2015 visit, uplifted fresh coral showed that inflation was ongoing and that the caldera was likely in the process of resurgence.

Much of Hunga Tonga and the 2014/2015 cone was destroyed in the 2022 eruptions, with Hunga Ha’apai intact, but dropping vertically by ~10-15 m. The violence of the 2022 eruption was likely augmented by either caldera collapse or flank collapse from the upper edifice, rapidly unroofing the andesitic magma system and enabling efficient water ingress.

This data provides an essential base layer for assessing changes on the ocean floor, especially to determine any caldera or upper-flank changes. Understanding these changes is crucial for future forecasting future volcanic hazards at Hunga and other nearby large submarine volcanoes.

How to cite: Stern, S., Cronin, S., Ribo, M., Barker, S., Brenna, M., Smith, I. E. M., Ford, M., Kula, T., and Vaiomounga, R.: Post-2015 caldera morphology of the Hunga Tonga-Hunga Ha’apai caldera, Tonga, through drone photogrammetry and summit area bathymetry, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13586, https://doi.org/10.5194/egusphere-egu22-13586, 2022.

09:01–09:08
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EGU22-13590
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Highlight
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Virtual presentation
Thomas R. Walter and Simone Cesca and the GFZ-DLR-Geomar Task Force Team

The Hunga-Tonga eruption culminated on January 15, 2022, with a high-intensity Plinian eruption exceeding 20 km height, tsunamis affecting local islands and the circumpacific region, locally air-coupled seismic surface waves recorded at teleseismic distances, and explosive shock waves that repeatedly travelled around the world. Hunga-Tonga is a flat-topped volcano that rises about 1700 m above the seafloor, hosting a submarine 3-4 km diameter caldera floor that lies at less than 200 m water depth and is surrounded by an elevated, approx. 100-200 m high caldera wall. Only small parts of the volcano are rising at the caldera wall above the sea level, such as the islands Hunga Tonga Hunga Ha'apai in the north and small unnamed rocks in the south. Satellite imagery acquired by Pleiades and Sentinel 1A suggests that during the January 15, 2022 eruption, the central part of the Hunga Tonga Hunga Ha'apai as well as the small rocks in the south disappeared. By analysing satellite radar and imagery, we constrain island perimeters and morphologies before and after the eruption, to find evidence for island subsidence and erosion. In addition, seismic data recorded during the January 15, 2022 eruption was analysed in the time and frequency domains, revealing high amplitude activity over ~1 hr. The comparison of seismic, GNSS and local tsunami recordings gives insights into the time-succession of the eruption. For instance, moment tensor inversion suggests that the largest amplitude seismic signal was produced by a dominant tensile non-double component, characteristic of volcanic explosions. Furthermore, we also found evidence for reverse polarity mechanisms in agreement with subsidence of a caldera, possibly indicating incremental activity of a ring fault. We discuss the possible contribution of a caldera to the evolving eruption dynamics and the need to improve geophysical monitoring of this island arc in general and acquire high-resolution submarine data Hunga Tonga Hunga Ha'apai in specific.

How to cite: Walter, T. R. and Cesca, S. and the GFZ-DLR-Geomar Task Force Team: Caldera subsidence during the Hunga-Tonga explosive eruption?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13590, https://doi.org/10.5194/egusphere-egu22-13590, 2022.

09:08–09:15
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EGU22-13599
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On-site presentation
Alexandre Baron, Guillaume Payen, Valentin Duflot, Patrick Chazette, Sergey Khaykin, Yann Hello, Nicolas Marquestaut, Marion Ranaivombola, Nelson Bègue, Thierry Portafaix, and Jean-Pierre Cammas

Explosive volcanism periodically induces disturbances of the upper troposphere and low stratosphere. These injections of massive amount of aerosols, ash and gases perturb locally the physico-chemical balance of the impacted atmospheric layers, in particular the ozone concentration via heterogeneous chemistry on particles. On a larger scale some exceptional eruption can have a significant influence on the Earth radiative budget as it was the case following eruptions of El Chichon in 1982 and Mount Pinatubo in 1991.

On January 15, 2022, the Hunga-Tonga volcano erupted in the Tonga archipelago (20.5°S, 175.4°W). The Plinian eruption was of a rare intensity, especially because of the depth of the underwater caldera. The first estimates indicate a power between 10 and 15 Mt TNT, probably the most powerful since the eruption of Krakatoa in 1883. This short (~ 8min) but intense explosion whose pressure wave was observed all around the globe injected about 400 kt of material into the atmosphere (to be compared to the 20 Mt injected during the Mount Pinatubo eruption). The Volcano Stratospheric Plume (VSP) quickly moved westwards and then overflew the island of La Réunion (21°S, 55°E), located at ~12000 km away from Tonga.

In order to monitor the evolution of the VSP, lidar observations were performed at the Observatoire de Physique de l’Atmosphère de La Réunion (OPAR). This observatory is equipped with three lidars capable of stratospheric aerosols measurements at two wavelengths (355 nm and 532 nm). First observations were performed every night from 19 to 27 January 2022 when the first passage of the VSP occurred. The plume structures appeared to be highly variable along time, with altitudes ranging from 19 km to 36 km above the mean sea level while plume thicknesses were ranging from ~1 km to more than 3 km. Remarkable aerosol optical depth were associated with these stratospheric aerosol layers, up to 0.8 at 532 nm on January 21.

The temporal evolution of the VSP structure and optical properties will be presented and discussed.

How to cite: Baron, A., Payen, G., Duflot, V., Chazette, P., Khaykin, S., Hello, Y., Marquestaut, N., Ranaivombola, M., Bègue, N., Portafaix, T., and Cammas, J.-P.: Early evolution of the Hunga – Tonga Volcanic Plume from Lidar Observations at Reunion Island (Indian Ocean, 21°S, 55°E), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13599, https://doi.org/10.5194/egusphere-egu22-13599, 2022.

09:15–09:22
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EGU22-13583
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Highlight
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Virtual presentation
Simon Carn, Benjamin Andrews, Valentina Aquila, Christina Cauley, Peter Colarco, Josef Dufek, Tobias Fischer, Lexi Kenis, Nickolay Krotkov, Can Li, Larry Mastin, Paul Newman, and Paul Wallace

The 15 January 2022 eruption of the submarine Hunga Tonga-Hunga Ha'apai (HTHH) volcano (Tonga) ranks among the largest volcanic explosions of the satellite remote sensing era, and perhaps the last century. It shares many characteristics with the 1883 Krakatau eruption (Indonesia), including atmospheric pressure waves and tsunamis, and the phreatomagmatic interaction of magma and seawater likely played a major role in the dynamics of both events. A portion of the HTHH eruption column rose to lower mesospheric altitudes (~55 km) and the umbrella cloud extent (~500 km diameter at ~30-35 km altitude) rivalled that of the 1991 Pinatubo eruption, indicative of very high mass eruption rates. However, sulfur dioxide (SO2) emissions measured in the HTHH volcanic cloud (~0.4 Tg) were significantly lower than the post-Pinatubo SO2 loading (~10–15 Tg SO2), and on this basis we would expect minimal climate impacts from the HTHH event. Yet, in the aftermath of the eruption satellite observations show a persistent stratospheric aerosol layer with the characteristics of sulfate aerosol, along with a large stratospheric water vapor anomaly. At the time of writing, the origin, composition and eventual impacts of this stratospheric gas and aerosol veil are unclear. We present the preliminary results of a multi-disciplinary approach to understanding the HTHH eruption, including 1D- and 3D-modeling of the eruption column coupled to a 3D atmospheric general circulation model (NASA’s GEOS-5 model), volatile mass balance considerations involving potential magmatic, seawater and atmospheric volatile and aerosol sources, and an extensive suite of satellite observations. Analysis of the HTHH eruption will provide new insight into the dynamics and atmospheric impacts of large, shallow submarine eruptions. Such eruptions have likely occurred throughout Earth’s history but have never been observed with modern instrumentation.

How to cite: Carn, S., Andrews, B., Aquila, V., Cauley, C., Colarco, P., Dufek, J., Fischer, T., Kenis, L., Krotkov, N., Li, C., Mastin, L., Newman, P., and Wallace, P.: Satellite observations and modeling of the 2022 Hunga Tonga-Hunga Ha'apai eruption, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13583, https://doi.org/10.5194/egusphere-egu22-13583, 2022.

09:22–09:29
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EGU22-13593
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ECS
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On-site presentation
Aurélien Podglajen, Raphaël Garcia, Solene Gerier, Alain Hauchecorne, Albert Hertzog, Alexis Le Pichon, Francois Lott, and Christophe Millet

In the frame of the Strateole 2 balloon project, 17 long-duration stratospheric balloons were launched from Seychelles in fall 2021. At the time of the main eruption of Hunga-Tonga on January 15 2022, two balloons were still in flight over the tropical Pacific, respectively at altitudes of 20 and 18.5 km, and distances of 2,200 and 7,600 km from the volcano. The balloon measurements include wind, temperature and pressure at a sampling rate of 1 Hz. Those observations of this extreme event at that altitude are unique.

In this presentation, we will describe the observations of multiple wave trains by the balloons. The signature of the Lamb wave and infrasounds are particularly striking. The characteristics of the eruption and its scenario will be examined using a synergy of stratospheric in situ observations, ground observations and geostationary satellite images. Finally, we will discuss the complementarity of balloon observations with respect to the ground network due to their altitude and geographic location with respect to the source.

How to cite: Podglajen, A., Garcia, R., Gerier, S., Hauchecorne, A., Hertzog, A., Le Pichon, A., Lott, F., and Millet, C.: Stratospheric observations of acoustic-gravity waves from the Hunga-Tonga eruption, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13593, https://doi.org/10.5194/egusphere-egu22-13593, 2022.

09:29–09:36
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EGU22-13595
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Virtual presentation
Bernard Legras, Sergey Khaykin, Aurélien Podglajen, and Pasquale Sellitto and the ASTuS

The Hunga Tonga eruption has generated an atmospheric plume rising above 40 km,  establishing an observational record. Due to the explosive nature of the eruption with a lot of water, the plume carried an unprecedented amount of water and a cloud of sulfated aerosols and possibly ultra-thin ashes was released. The aerosols have already persisted for four weeks with peak scatterring ratio initially above 200 that are still above 30 on many patches, as seen from CALIOP. These high values combined with low depolarization suggest a large amount of small sub-micronic spherical particles, confirmed by in situ balloon measurements. This is compatible with dominance of sulfated aerosols.

As the stratospheric flow has been mostly zonal with no breaking wave during the period and region of interest, and the horizontal shear dominates, the plume has been mostly dispersed in longitude keeping a similar latitudinal vertical pattern from the early days. A part has migrated to the tropical band reaching 10°N. Several concentrated patches have been preserved in particular a "mushroom" like pattern at 20S which has already circulated once around the Earth. . We will discuss the stability of this pattern in relation with vortical and thermal structures that are detected from several instruments and the meteorological analysis.

We will also discuss the likely impact on the stratospheric composition and the radiative effect on the yearly basis.  

How to cite: Legras, B., Khaykin, S., Podglajen, A., and Sellitto, P. and the ASTuS: Persistence Hunga Tonga plume in the stratosphere and its journey around the Earth., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13595, https://doi.org/10.5194/egusphere-egu22-13595, 2022.

09:36–09:43
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EGU22-13578
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ECS
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On-site presentation
Edhah Munaibari, Lucie Rolland, Anthony Sladen, and Bertrand Delouis

The Hunga Tonga volcanic eruption on Jan. 15, 2022 released a highly energetic atmospheric pressure wave that was observed all around the globe in different types of measurements (e.g., barometers and infrasound sensors, satellites images, ionospheric measurements, etc.). In addition, the eruption triggered a meteo-tsunami followed by a series of tsunami waves. Tide gauges across the Pacific Ocean, the Atlantic and the Indian oceans recorded significant sea-level changes related to the primary eruption.

We focus our presentation on the imprint of tsunami waves on the ionosphere. We make use of an extensive collection of Global Navigation Satellites Systems (GNSS) data recorded by multi-constellation GNSS receivers across the Pacific Ocean and beyond. The observation of tsunami-induced ionospheric signatures is made possible by the efficient coupling of tsunami waves with the surrounding atmosphere and the generation of internal gravity waves (IGWs). With the help of GNSS systems (Beidou, GPS, Galileo, GLONASS, QZSS), ionospheric disturbances can be monitored and observed by utilizing the Total Electron Content (TEC) derived from the delay that the ionosphere imposes in the electromagnetic signals transmitted by the GNSS satellites. We identify and characterize the ionospheric TEC signatures following the passage of the Tonga tsunami. We investigate the influence of known key ambient parameters such as the local geomagnetic field, the tsunami propagation direction, and the distance to the tsunami source on the amplitude of the observed signatures. Moreover, we correlate the detected tsunami-induced TEC signatures with sea level measurements to assess their tsunami origins. And we contrast the identified TEC signatures in the Pacific Ocean with their analogs induced by the tsunami triggered by the Mar. 4, 2021 8.1 Mw Kermadec Islands earthquake. Both events took place relatively in the same geographical region, with the former being less complex (no meteo-tsunami, shorter duration, and about one order of magnitude smaller in amplitude). Finally, we provide estimations of the tsunami amplitude at the ocean level in the areas crossed by GNSS radio signals, some of them not covered by open ocean sea-level sensors (DART buoys).

How to cite: Munaibari, E., Rolland, L., Sladen, A., and Delouis, B.: Global ionospheric signature of the tsunami triggered by the 2022 Hunga Tonga volcanic eruption, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13578, https://doi.org/10.5194/egusphere-egu22-13578, 2022.

09:43–09:50
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EGU22-13592
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ECS
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Highlight
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Virtual presentation
Boris Maletckii and Elvira Astafyeva

The 15th January 2022 Hunga Tonga- Hunga Ha’apai (HTHH) volcano explosion is one of the most powerful eruptive events over the last 30 years. Based on early computations, its VEI was at least 5. The explosion caused atmospheric air shock waves that propagated around the globe, and also generated a tsunami. All these effects seemed to have produced quite a significant response in the ionosphere.

In this contribution, we analyze the ionospheric disturbances generated by the HTHH volcano eruption by using ground-based 8 GNSS receivers located in the near-field of the volcano (i.e., less than 2000 km). We test our previously developed methods to detect and locate the explosive event and its ionospheric signatures in a near-real-time (NRT) scenario. 

To detect co-volcanic ionospheric disturbances (co-VID), we use the TEC time derivative approach that was previously used for detection of ionospheric disturbances generated by large earthquakes. For this event, we modified the previously developed method to proceed not only 1-second but also 30 sec data. This approach detects the first perturbations ~12-15 minutes after the eruption onset. Further, it estimates the instantaneous velocities in a near field to be about ~500-800 m/s. Finally, from the obtained velocity vectors and the azimuths of co-VID propagation we calculate the position of the source in the ionosphere. 

Besides, we used the same TEC time derivative approach to produce NRT Travel Time Diagrams. The NRT TTD additionally verify the correlation with the source and velocities’ values.

How to cite: Maletckii, B. and Astafyeva, E.: The Near Real time analysis of Hunga Tonga-Hunga Ha’apai eruption in the ionosphere by GNSS, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13592, https://doi.org/10.5194/egusphere-egu22-13592, 2022.

09:50–09:57
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EGU22-13580
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ECS
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On-site presentation
Bruce Enki Oscar Thomas, Jean Roger, and Yanni Gunnell

The population and built infrastructure of the Kingdom of Tonga are highly exposed to ocean- and climate-related coastal hazards. The archipelago was impacted on January 15, 2022, by a destructive tsunami caused by the Hunga Tonga-Hunga Ha'apai submarine volcanic eruption. Weeks later, several islands were still cut off from the world, this situation was made worse by covid-19-related international lockdowns and no precise idea of the magnitude and pattern of destruction. Like in most Pacific islands, the Kingdom of Tonga lacks an accurate population and infrastructure database. The occurrence of events such as this in remote island communities highlights the need for (1) precisely knowing the distribution of residential and public buildings, (2) evaluating what proportion of those would be vulnerable to a tsunami depending on various run-up scenarios, (3) providing tools to the local authorities for elaborating efficient evacuation plans and securing essential services outside the hazard zones. Using a GIS-based dasymetric mapping method previously tested in New Caledonia for assessing, calibrating, and mapping population distribution at high resolution, we produce maps that combine population clusters, critical elevation contours, and the precise location of essential services (hospitals, airports, shopping centers, etc.), backed up by before–after imagery accessible online. Results show that 62% of the population on the main island of Tonga lives in well-defined clusters between sea level and the 15 m elevation contour, which is also the value of the maximum tsunami run-up reported on this occasion. The patterns of vulnerability thus obtained for each island in the archipelago, are further compared to the destruction patterns recorded after the earthquake-related 2009 tsunami in Tonga, thereby also allowing us to rank exposure and potential for cumulative damage as a function of tsunami cause and source-area. By relying on low-cost tools and incomplete datasets for rapid implementation in the context of natural disasters, this approach can assist in (1) guiding emergency rescue targets, and (2) elaborating future land-use planning priorities for disaster risk-reduction purposes. By involving an interactive mapping tool to be shared with the resident population, the approach aims to enhance disaster-preparedness and resilience. It works for all types of natural hazards and is easily transferable to other insular settings.

How to cite: Thomas, B. E. O., Roger, J., and Gunnell, Y.: A rapid, low-cost, high-resolution, map-based assessment of the January 15, 2022 tsunami impact on population and buildings in the Kingdom of Tonga, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13580, https://doi.org/10.5194/egusphere-egu22-13580, 2022.

Coffee break
Chairpersons: David Tappin, Hélène Hébert, Torsten Dahm
10:20–10:30
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EGU22-13572
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solicited
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Virtual presentation
Piero Poli and Nikolai Shapiro

Most of the largest volcanic activity in the world occurs in remote places as deep oceans or poorly monitored oceanic islands. Thus, our capacity of monitoring volcanoes is limited to remote sensing and global geophysical observations. However, the rapid estimation of volcanic eruption parameters is needed for scientific understanding of the eruptive process and rapid hazard estimation. We first a method to rapidly identify large volcanic explosions, based on analysis of seismic data. The method automatically detects and locate long period (0.01-0.03Hz) signals associated with physical processes close to the Earth surface, by analyzing surface waves recorded at global seismic stations. With this methodology, we promptly detect the January 15, 2022 Hunga Tonga eruption, among many other signals associated with known and unknown processes. We further use the waves generate by the Hunga Tonga volcanic explosion and estimate important first-order parameters of the eruption (Force spectrum, impulse). We then relate the estimated parameters with the volcanic explosivity index (VEI). Our estimate of VEI~6, indicate how the Hunga Tonga eruption is among the largest volcanic activity ever recorded with modern geophysical instrumentation, and can provide new insights about the physics of large volcanoes.

How to cite: Poli, P. and Shapiro, N.: Seismological characterization of dynamics parameter of the Hunga Tonga explosion from teleseismic waves, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13572, https://doi.org/10.5194/egusphere-egu22-13572, 2022.

10:30–10:37
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EGU22-13598
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Presentation form not yet defined
Julien Vergoz, Alexis Le Pichon, Constantino Listowski, Patrick Hupe, Christopher Pilger, Peter Gaebler, Lars Ceranna, Milton Garcés, Emanuele Marchetti, Philippe Labazuy, Pierrick Mialle, Quentin Brissaud, Peter Näsholm, Nikolai Shapiro, and Piero Poli

The eruption of Hunga volcano, Tonga is the most energetic event recorded by the infrasound component of the global International Monitoring System (IMS). Infrasound, acoustic-gravity and Lamb waves were recorded by all 53 operational stations after circling four times the globe. The atmospheric waves recorded globally exhibit amplitude and period comparable to the ones observed following the 1883 Krakatoa eruptions. In the context of the future verification of the Comprehensive Nuclear-Test-Ban Treaty, this event provides a prominent milestone for studying in detail infrasound propagation around the globe for almost one week as well as for calibrating the performance of the IMS network in a broad frequency band.

How to cite: Vergoz, J., Le Pichon, A., Listowski, C., Hupe, P., Pilger, C., Gaebler, P., Ceranna, L., Garcés, M., Marchetti, E., Labazuy, P., Mialle, P., Brissaud, Q., Näsholm, P., Shapiro, N., and Poli, P.: A global analysis of deep infrasound produced by the January 2022 eruption of Hunga volcano, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13598, 2022.

10:37–10:44
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EGU22-13576
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ECS
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Virtual presentation
Elizaveta Tsukanova, Alisa Medvedeva, Igor Medvedev, and Tatiana Ivelskaya

The Hunga Tonga volcanic eruption on 15 January 2022 created a tsunami affecting the entire Pacific Ocean. The observed tsunami was found to have a dual mechanism and was caused both by the wave incoming from the source area and by an atmospheric wave propagating with the speed of sound. The tsunami was clearly recorded in the marginal seas of the northwestern Pacific, including the Sea of Japan, the Sea of Okhotsk and the Bering Sea, in particular on the coasts of Kamchatka, the Kuril Islands and the Aleutian Islands. We examined high-resolution records (1-min sampling) of about 50 tide gauges and 15 air pressure stations in these seas for the period of 14-17 January 2022. On the Russian coast, the highest wave with a trough-to-crest wave height of 1.4 m was recorded at Vodopadnaya, on the southeastern Kamchatka Peninsula; on the coasts of the Aleutian Islands the tsunami waves were even higher, up to 2 m. Based on numerical modelling we estimated the arrival time of the gravitational tsunami waves from the source. We revealed that the character of sea level oscillations for most of the stations evidently changed before these waves arrived. A comparative analysis of sea level and atmospheric data indicated that these changes were probably caused by the atmospheric waves generated by the volcanic eruption.

How to cite: Tsukanova, E., Medvedeva, A., Medvedev, I., and Ivelskaya, T.: The 2022 Tonga tsunami in the marginal seas of the northwestern Pacific Ocean, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13576, https://doi.org/10.5194/egusphere-egu22-13576, 2022.

10:44–10:51
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EGU22-13579
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ECS
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Virtual presentation
Shenjian Zhang, Rongjiang Wang, and Torsten Dahm

Low-frequency seismic energy whose spectrum is centered at certain narrow bands has been detected after violent volcano eruptions. Normal-mode analysis related this signal to the resonances between the atmosphere and the solid earth.
After the powerful eruption of Hunga Tonga-Hunga Ha’apai volcano on Jan. 15, 2022, this low-frequency signal is found on long period and very long period seismometers worldwide. The amplitude spectrum of the signal for this eruption consists of three clear peaks locating at 3.72, 4.61 and 6.07 mHz, instead of two distinct bands for previous cases. The spectrogram analysis shows that this low-frequency energy lasts for several hour and is independent of air wave arrival, while the cross-correlation result confirms that the signal travels as Rayleigh waves with a speed of 3.68 km/s. In this study, we summarize our findings on the observation, and show our synthetic waveforms to provide a possible explanation for the source of this signal. We suggest that the atmospheric oscillations near the volcano excited by the eruption act as an enduring external force on the surface of the solid earth, and produce Rayleigh waves propagating all over the world.

How to cite: Zhang, S., Wang, R., and Dahm, T.: Modeling low-frequency Rayleigh waves excited by the Jan. 15, 2022 eruption of Hunga Tonga-Hunga Ha’apai volcano, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13579, https://doi.org/10.5194/egusphere-egu22-13579, 2022.

10:51–10:58
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EGU22-13581
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Virtual presentation
Rudolf Widmer-Schnidrig

The phreatic eruption of Hunga-Tonga on January 15, 2022 was so energetic that it excited globe circling air-waves. These wave packets with a dominant period of 30 minutes have been observed in single barograms even after completing at least  four orbits or 6 days after the eruption. Constructive and destructive interference between waves that have left the source region in opposite direction lead to the emergence of standing pressure waves: normal modes of the atmosphere.

 

We report on individual modes of spherical harmonic degree between 30 and 80 covering the frequency bend from 0.2 mHz to 0.8 mHz. These modes belong to the Lamb wave equivalent modes with a phase velocity of 313 m/s.  They are trapped to the Earth’s surface, decay exponentially with altitude and their particle motion is longitudinal and horizontal. The restoring force is dominated by incompressibility. 

 

In the frequency band where we observe these modes the mode branches do not cross with mode branches of the solid Earth. Hence we do not expect any significant coupling with seismic normal modes of the solid Earth. Such a crossing occurs at 3.7mHz and aboce.

 

How to cite: Widmer-Schnidrig, R.: Observation of acoustic normal modes of the atmosphere after the 2022 Hunga-Tonga eruption., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13581, https://doi.org/10.5194/egusphere-egu22-13581, 2022.

10:58–11:05
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EGU22-13591
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Presentation form not yet defined
Mikhail Nosov, Kirill Sementsov, Sergey Kolesov, and Vasilisa Pryadun

The explosive eruption of the Hunga Tonga-Hunga Ha'apai volcano on January 15, 2022 triggered tsunami waves that were observed throughout the Pacific Ocean. In particular, the waves were recorded by several dozen deep-ocean DART stations located at source distances from hundreds to more than 10 thousand kilometers. Our study is aimed at analyzing tsunami waveforms recorded by DART stations in order to identify the formation mechanisms of this volcanogenic tsunami. Waveforms are processed using wavelet analysis. The arrival times of signals of different genesis are estimated making use robust physical assumptions, numerical modeling and satellite images. It has been found that in all records the tsunami signal is clearly observed long before the calculated moment of arrival of gravity surface waves caused by sources localized in the immediate vicinity of the volcano. On the records obtained by distant stations (~10000 km) dispersive gravity waves arrive with a delay of several hours after the signals following the passage of acoustic wave in the atmosphere. In addition to the analysis of waveforms, theoretical estimates of the amplitude of gravity waves in the ocean, caused by an acoustic wave in the atmosphere, will be presented. We also provide a theoretical estimate on how acoustic waves in the atmosphere manifest in pressure variations recorded by an ocean-bottom sensor.

This study was funded by a grant of the Russian Science Foundation № 22-27-00415, https://rscf.ru/en/project/22-27-00415/.

How to cite: Nosov, M., Sementsov, K., Kolesov, S., and Pryadun, V.: Volcanogenic tsunami on January 15, 2022: insights from deep-ocean measurements, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13591, https://doi.org/10.5194/egusphere-egu22-13591, 2022.

11:05–11:12
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EGU22-13589
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Highlight
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On-site presentation
Alberto Armigliato, Cesare Angeli, Glauco Gallotti, Stefano Tinti, Martina Zanetti, and Filippo Zaniboni

The Hunga Tonga-Hunga Ha’apai eruption of January 15 2022 was the culminating event of a sequence of seismic and volcanic events starting back in December 2021. The January 15 eruption manifested itself above the sea level with a number of phenomena, including the generation of a convective column ascending well into the stratosphere, pyroclastic flows travelling over the sea surface, an atmospheric pressure wave recorded by several instruments around the globe, and a tsunami, that represents the main focus of this study.

The tsunami that followed the eruption was observed both in the near-field and in the far-field, propagating across the entire Pacific Ocean and causing damage and loss of lives as far as Peru. In the near-field (Tonga archipelago) it is trickier to distinguish the damage induced by the impact of the eruption and the tsunami waves.

It is still not clear what the main generating mechanism for the ensuing tsunami was. In this contribution, several different hypotheses are investigated, adopting simplified models ranging from the submerged volcanic edifice collapse to the phreatomagmatic explosion and to the atmospheric pressure wave that was recorded across the entire globe. The propagation of the tsunami is simulated numerically with both non-dispersive and dispersive codes. Different spatial scales and resolutions are adopted to check the relative weight of the different generating mechanisms in the near- and in the far-field. Tentative conclusions are drawn by comparing the simulated results with the available experimental data in terms of tide-gauge records and near-field coastal impact.

How to cite: Armigliato, A., Angeli, C., Gallotti, G., Tinti, S., Zanetti, M., and Zaniboni, F.: Numerical investigations on different possible generating mechanisms for the tsunami following the January 15 2022 Hunga Tonga-Hunga Ha’apai eruption, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13589, https://doi.org/10.5194/egusphere-egu22-13589, 2022.

11:12–11:19
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EGU22-13594
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Highlight
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Virtual presentation
Audrey Gailler, Philippe Heinrich, Vincent Rey, Hélène Hébert, Aurélien Dupont, Constantino Listowski, Edouard Forestier, and Stavros Ntafis

Meteotsunamis are long ocean waves generated by atmospheric disturbances. The Tonga volcano eruption on 15 January 2022 generated a Lamb pressure wave propagating all over the globe and generating a tsunami observed at most tide gauges in the world. A first atmospheric wave arrived 20 hours after the eruption on the French Mediterranean coasts and propagated southward. This abrupt atmospheric pressure change was recorded by hundreds of barometers of weather stations around Europe. A second one originating from Africa was observed four hours later with an attenuated amplitude. The first wave can be roughly defined by a sinusoid signal with a period close to one hour and an amplitude of 150 Pa. The associated tsunami was observed by the French stations of the HTM-NET network (https://htmnet.mio.osupytheas.fr/) [1]. Amplitudes range from a few cm to 15 cm and periods range from 20 min to 1 hour.

 

Numerical simulation of the tsunami is performed by the operational code Taitoko developed at CEA [2]. The nested multigrid approach is used to simulate the water waves propagating in the bay of Toulon. The meteotsunami is generated by calculating analytically the atmospheric pressure gradient in the momentum equation. Comparisons of time series between numerical solutions and records are very satisfactory in regions defined by a high resolution topo-bathymetry. A second tsunami simulation is performed by introducing a second pressure wave propagating in the North direction and reaching the HTM-NET stations 4 hours after the first arrival. This second pressure wave results in additional and higher tsunami water waves in agreement with records.

 

 

[1] Rey, V., Dufresne, C., Fuda, J. L., Mallarino, D., Missamou, T., Paugam, C., Rougier, G., Taupier-Letage, I., On the use of long term observation of water level and temperature along the shore for a better understanding of the dynamics: Example of Toulon area, France Ocean Dyn., 2020, https://doi.org/10.1007/s10236-020-01363-7.

[2] Heinrich, P, Jamelot, A., Cauquis, A., Gailler A., 2021. Taitoko, an advanced code for tsunami propagation, developed at the French Tsunami Warning Centers. European Journal of Mechanics - B/Fluids 88(84) . DOI: 10.1016/j.euromechflu.2021.03.001.

How to cite: Gailler, A., Heinrich, P., Rey, V., Hébert, H., Dupont, A., Listowski, C., Forestier, E., and Ntafis, S.: Observation and simulation of the meteotsunami generated in the Mediterranean Sea by the Tonga eruption on 15 January 2022, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13594, https://doi.org/10.5194/egusphere-egu22-13594, 2022.

11:19–11:26
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EGU22-13588
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On-site presentation
Jadranka Sepic, Igor Medvedev, Isaac Fine, Richard Thomson, and Alexander Rabinovich

The Tonga volcanic eruption of 15 January 2022 generated tsunami waves that impacted the entire Global Ocean as far away as 18,000 km from the source in the tropical Pacific Ocean. A defining characteristic of the tsunami was the dual forcing mechanism that sent oceanic waves radiating outward from the source at the longwave speed and atmospheric pressure Lamb waves radiating around the globe at the speed of sound (i.e. roughly 1.5 times faster than the longwave phase speed). Based on time series from several hundred high-resolution observational sites, we constructed global maps of the oceanic tsunami waves and the atmospheric Lamb waves. In some areas of the Pacific Ocean, we were able to distinguish between the two types of motions and estimate their relative contribution. A global numerical model of tsunami waves was constructed and results from the model compared with the observations. The modeled and observed tsunami wave heights were in good agreement. The global maps also enabled us to identify regional “hot spots” where the tsunami heights were highest. In addition to areas in the Pacific Ocean (Chile, New Zealand, Japan, the U.S. West Coast, and the Alaska/Aleutian Islands), “hot regions” included the Western Mediterranean and the Atlantic coasts of Europe and northern Africa.

How to cite: Sepic, J., Medvedev, I., Fine, I., Thomson, R., and Rabinovich, A.: The global reach of the 2022 Tonga volcanic eruption, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13588, https://doi.org/10.5194/egusphere-egu22-13588, 2022.

11:26–11:33
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EGU22-13596
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Virtual presentation
World-wide gravity and pressure signals detected during the eruption at Hunga-Tonga.
(withdrawn)
Philippe Jousset, Jacques Hinderer, Michel van Camp, Andreas Güntner, Harmut Wziontek, Daniele Carbone, and Lotte Krawczyk
11:33–11:40
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EGU22-13582
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ECS
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Presentation form not yet defined
Felix Eckel, Milton Garcés, and Meritxell Colet

The explosive eruption of the Hunga Tonga-Hunga Ha’apai volcano on 15th of January 2022 impacted the Earth, its oceans and atmosphere on a global scale. Witnesses report an audible “bang” as a result of the event in distances of up to several thousand kilometers. With infrasound sensors this sound wave can be detected where the frequency content or the amplitude of the signal renders the event inaudible to the human ear. Infrasound sensors are distributed globally, a selection of these stations upload their data in real time to publicly available servers. In combination with Open Source libraries such as obspy or scipy it is possible to use these data sources to observe the atmospheric disturbances caused by the eruption on a global scale in near real time. With a minimum of data processing not only the first arrival peak of the atmospheric lamb wave can be identified at most stations but also further passes of the wave as it propagates around the planet several times. Having large amounts of publicly available data is crucial in that process. New data chunks can be analyzed and displayed immediately while the signal is still ongoing because data access requests are not required. Additionally, having immediate access to a large dataset allows for big data analysis and reduces the necessity to consider outliers at individual stations and increases the chance to identify the signal after multiple days when overall signal to noise ratios have decreased.

How to cite: Eckel, F., Garcés, M., and Colet, M.: The 15 January 2022 Hunga Tonga event: Using Open Source to observe a volcanic eruption on a global scale in near real time, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13582, https://doi.org/10.5194/egusphere-egu22-13582, 2022.

11:40–11:47
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EGU22-13601
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Virtual presentation
Luis Millán, Lucien Froidevaux, Gloria Manney, Alyn Lambert, Nathaniel Livesey, Hugh Pumphrey, William Read, Michelle Santee, Michael Schwartz, Hui Su, Frank Werner, and Longtao Wu

Hunga Tonga-Hunga Haʻapai, a submarine volcano in the South Pacific, reached an eruption climax on 15 January 2022. The blast sent a plume of ash well into the stratosphere, triggered tsunami alerts across the world, and caused ionospheric disturbances. A few hours after the violent eruption, the Microwave Limb Sounder (MLS) measured enhanced values of water vapor at altitudes as high as 50 km - near the stratopause.
On the following days, as the plume dispersed, several MLS chemical species, including H2O and SO2, displayed elevated values, far exceeding any previous values in the 18-year record. In this presentation we discuss the validity of these measurements, the stratospheric evolution of the SO2 and H2O plumes, and, lastly, the implications of the large-scale hydration of the stratosphere by the eruption.

How to cite: Millán, L., Froidevaux, L., Manney, G., Lambert, A., Livesey, N., Pumphrey, H., Read, W., Santee, M., Schwartz, M., Su, H., Werner, F., and Wu, L.: The Hunga Tonga-Hunga Haʻapai hydration of the stratosphere, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13601, https://doi.org/10.5194/egusphere-egu22-13601, 2022.