Uitbarsting vulkaan Hunga Tonga (incl. tsunami + nasleep)

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How the Tonga volcano eruption from 2022 may affect Australia's weather for up to eight years

Lasting impacts from an enormous volcanic eruption a year ago may have a cooling and rainy influence on parts of Australia for up to eight years, according to scientists.

In January 2022, the underwater volcano Hunga Tonga-Hunga Ha'apai erupted, shooting ash and other particles more than half way to space.

The eruption triggered a tsunami that reached heights of more than 19 metres above sea level, and created long lasting and vivid sunsets for several months following.

But the powerful explosion also caught the intrigue of scientists around the globe, fascinated by its potential impacts on climate.

Of particular interest was the record-breaking amount of water vapour, a strong greenhouse gas, which it pumped into the stratosphere.

So a year on, what do we know about its influence on Australian weather?

Volcano potentially added to rain on east coast
Martin Jucker, from the University of New South Wales Climate Change Research Centre, is leading a research paper exploring the impacts of the eruption's water vapour on Australian weather.

The paper is currently at peer review stage.

Dr Jucker said while it was too early to provide solid answers with the paper still under review, they did have some idea about what the impacts might be on weather in Australia.

These included a potential increase in rainfall over the east coast of Australia, south of about Brisbane, between mid-February 2022 and mid-April 2022.

"So we can say, around March, April last year, the volcano would probably have favoured rain in Australia on the east coast," he said

This was by moving a large band of cloud, known as the South Pacific Convergence Zone (SPCZ), closer to Australia.

"The South Pacific Convergence Zone is where it rains a lot," Dr Jucker said.

"It's basically constantly cloudy.

"And so if that moves further south-west, that move means this band of rain moves closer to the (Australian) coast."

Dr Jucker said they were "quite confident" about the correlation between the eruption and the shift in position of the SPCZ."

But he said they could not put a figure on how much of an influence on rainfall it had during that time.

This was because it was too hard to untangle from other factors, such as La Nina, climate change and natural variability.

He said they also could not link it to a specific weather event, such as the Lismore flooding which occurred during this period, for the same reasons.

Possible cooling in WA and northern Australia
Dr Jucker said there could also be impacts to temperature for up to eight years because of how long it takes for particles to clear out of the stratosphere.

While our day-to-day weather occurs in the troposphere, the bottom layer of the atmosphere, conditions in the stratosphere can have flow-on impacts to how weather systems at the surface behave.

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Tonga Underwater Volcano Eruption Disrupted Satellite Signals Halfway Around the World

Research shows that volcanic eruptions can create plasma bubbles in the ionosphere, significantly disrupting satellite communication. These findings prompt revisions to the current models on atmospheric and ionospheric interactions.

An international team has used satellite- and ground-based ionospheric observations to demonstrate that an air pressure wave triggered by volcanic eruptions could produce an equatorial plasma bubble (EPB) in the ionosphere, severely disrupting satellite-based communications. Their findings will be published today (May 22) in the journal Scientific Reports.

The ionosphere is the region of the Earth’s upper atmosphere where molecules and atoms are ionized by solar radiation, creating positively charged ions. The area with the highest concentration of ionized particles is called the F-region, an area 150 to 800 km above the Earth’s surface. The F-region plays a crucial role in long-distance radio communication, reflecting and refracting radio waves used by satellite and GPS tracking systems back to the Earth’s surface.

These important transmissions can be disrupted by irregularities in the F-region. During the day, the ionosphere is ionized by the Sun’s ultraviolet radiation, creating a density gradient of electrons with the highest density near the equator. However, disruptions to this, such as the movement of plasma, electric fields, and neutral winds, can cause the formation of a localized irregularity of enhanced plasma density. This region can grow and evolve, creating a bubble-like structure called an EPB. EPB can delay radio waves and degrade the performance of GPS.

Since these density gradients can be affected by atmospheric waves, it has long been hypothesized that they are formed by terrestrial events such as volcanic activity. For an international team led by Designated Assistant Professor Atsuki Shinbori (he, him) and Professor Yoshizumi Miyoshi (he, him) of the Institute for Space–Earth Environmental Research (ISEE), Nagoya University, in collaboration with NICT, The University of Electro-Communications, Tohoku University, Kanazawa University, Kyoto University and ISAS, the Tonga volcano eruption offered them a perfect opportunity to test this theory

The Tonga volcano eruption was the biggest submarine eruption in history. This allowed the team to test their theory using the Arase satellite to detect EPB occurrences, the Himawari-8 satellite to check the initial arrival of air pressure waves and ground-based ionospheric observations to track the motion of the ionosphere. They observed an irregular structure of the electron density across the equator that occurred after the arrival of pressure waves generated by the volcanic eruption.

“The results of this study showed EPBs generated in the equatorial to low-latitude ionosphere in Asia in response to the arrival of pressure waves caused by undersea volcanic eruptions off Tonga,” Shinbori said.

The group also made a surprising discovery. For the first time, they showed that ionospheric fluctuations start a few minutes to a few hours earlier than the atmospheric pressure waves involved in the generation of plasma bubbles. This could have important implications because it suggests that the long-held model of geosphere-atmosphere-cosmosphere coupling, which states that ionospheric disturbances only happen after the eruption, needs revision.

“Our new finding is that the ionospheric disturbances are observed several minutes to hours before the initial arrival of the shock waves triggered by the Tonga volcanic eruption,” Shinbori said. “This suggests that the propagation of the fast atmospheric waves in the ionosphere triggered the ionospheric disturbances before the initial arrival of the shock waves. Therefore, the model needs to be revised to account for these fast atmospheric waves in the ionosphere.”

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Giant Eruption Plume from Tonga’s Volcano Produced Most Intense Lightning Rates Ever Detected

On January 15, 2022, Hunga Volcano in Tonga produced the most violent eruption in the modern satellite era, sending a water-rich plume at least 58 km (36 miles) high. This plume created record-breaking amounts of volcanic lightning observed both from space and by radio antennas on the ground thousands of kilometers away. New research shows that the eruption created more lightning — 2,615 flashes per minute at peak intensity — than any storm yet documented on Earth, including supercells and tropical cyclones. The peak lightning rate is significantly higher than the second most intense lightning event ever detected — 993 flashes per minute — in a thunderstorm over the southern United States in 1999.

An explosive eruption began on December 19, 2021 near the remote islands of Hunga Tonga and Hunga Ha’apai in the South Pacific Ocean.

These two islands are small peaks on the rim of a much larger submarine caldera volcano known as Hunga Volcano.

The explosive activity intensified on January 13, 2022, followed by the climactic eruption on January 15 that sent a water-rich volcanic plume into the mesosphere of our planet.

In addition to significant local impacts on the Kingdom of Tonga, the eruption created global-scale acoustic waves, tsunamis, ionospheric and geomagnetic disturbances, and warmed the climate due to water vapor injection.

The event continues to push the boundaries of our understanding of how explosive volcanism impacts the broader Earth system.

“This eruption triggered a supercharged thunderstorm, the likes of which we’ve never seen,” said lead author Dr. Alexa Van Eaton, a volcanologist at the U.S. Geological Survey.

“These findings demonstrate a new tool we have to monitor volcanoes at the speed of light and help the U.S. Geological Survey’s role to inform ash hazard advisories to aircraft.”

“The storm developed because the highly energetic expulsion of magma happened to blast through the shallow ocean.”

“Molten rock vaporized the seawater, which rose up into the plume and eventually formed electrifying collisions between volcanic ash, supercooled water and hailstones. The perfect storm for lightning.”

Combining data from sensors that measure light and radio waves, Dr. Van Eaton and colleagues tracked lightning flashes and estimated their heights.

The eruption produced just over 192,000 flashes (made up of nearly 500,000 electrical pulses), peaking at 2,615 flashes per minute.

Some of this lightning reached unprecedented altitudes in Earth’s atmosphere, between 20 to 30 km (12-19 miles) high.

“With this eruption, we discovered that volcanic plumes can create the conditions for lightning far beyond the realm of meteorological thunderstorms we’ve previously observed,” Dr. Van Eaton said.

“It turns out, volcanic eruptions can create more extreme lightning than any other kind of storm on Earth.”

The lightning provided insight into not only the duration of the eruption, but also its behavior over time.

“The eruption lasted much longer than the hour or two initially observed,” Dr. Van Eaton said.

“The January 15 activity created volcanic plumes for at least 11 hours. It was really only from looking at the lightning data that we were able to pull that out.”

The researchers saw four distinct phases of eruptive activity, defined by plume heights and lightning rates as they waxed and waned.

“The insights gained from linking lightning intensity to eruptive activity can provide better monitoring and nowcasting of aviation-related hazards during a large volcanic eruption, including ash cloud development and movement,” Dr. Van Eaton said.

Onderwatervulkaan slingerde in 2022 150 miljoen ton waterdamp de atmosfeer in
NASA constateert opwarmingseffect, IPCC negeert het

Onderwatervulkaan slingerde in 2022 150 miljoen ton waterdamp de atmosfeer in
NASA constateert opwarmingseffect, IPCC negeert het

Dagelijks wordt ons verteld dat CO2 een problematisch broeikasgas is, verantwoordelijk voor de opwarming van de aarde. Waterdamp is echter een vele malen sterker broeikasgas, ook al lijkt het IPCC dat te negeren. In januari 2022 barstte de onderwatervulkaan Hunga Tonga in de Stille Zuidzee uit en slingerde 150 miljoen ton waterdamp de atmosfeer in. De NASA waarschuwde vervolgens voor tijdelijke opwarming. Zou dat nu het geval zijn? Er zijn nog heel wat klimaatpuzzels op te lossen, schrijft Ferdinand Meeus.

Temidden van alle klimaathysterie zou men wel eens kunnen vergeten dat de aarde over immense oerkrachten beschikt. Zo bericht de NASA over een enorme uitbarsting in januari 2022 van de onderwatervulkaan Hunga Tonga in de Stille Zuidzee. De boodschap: de immense hoeveelheid waterdamp die door de vulkaan in de atmosfeer werd geslingerd, zou kunnen leiden tot tijdelijke opwarming van het aardoppervlak.

De spectaculaire eruptie van Hunga Tonga had een kracht van meerdere Hiroshima-atoombommen. "We hebben nog nooit zoiets gezien", zegt Luis Millán, een atmosferische wetenschapper bij NASA's Jet Propulsion Laboratory, California Institute of Technology in Pasadena. Tot in Nederland werden er luchtdrukverschillen gemeten door de kracht van de schokgolven. Gelukkig was tijdens de uitbarsting de NASA-satelliet Aura in de buurt. Voorzien van een uiterst gevoelige Microwave Limb Sounder sensor die tot vijftien verschillende sporen gas kan detecteren die belangrijk zijn voor de beïnvloeding van atmosferische klimaatprocessen.

150 miljoen ton waterdamp
In een studie, gepubliceerd in Geophysical Research Letters, schatten Millán en zijn collega's dat de Tonga-uitbarsting ongeveer 150 miljoen ton (!) waterdamp de atmosfeer inslingerde, tot op 53 km hoogte. Dat is een verhoging van wel 10% van de normaal aanwezige hoeveelheid waterdamp in de atmosfeer. Overeenkomend met bijna vier keer de hoeveelheid waterdamp die vrijkwam bij de uitbarsting van de Pinatubo in 1991 in de Filipijnen.

De grote hoeveelheid waterdamp die door de Tonga-vulkaan werd uitgestoten kan volgens de wetenschappers van NASA enkele jaren in de stratosfeer blijven en daardoor de atmosferische processen beïnvloeden. Met als gevolg chemische reacties die de aantasting van de ozonlaag tijdelijk kunnen verergeren en een effect hebben op wolkenvorming. De extra waterdamp kan ook direct de oppervlaktetemperatuur beïnvloeden, aangezien waterdamp een heel sterk broeikasgas is, en wel veel sterker dan CO2.



Belangrijkste broeikasgas
Ook volgens het KNMI is waterdamp het belangrijkste broeikasgas. Op de KNMI Kennis&Uitleg-pagina kunnen we lezen dat "bijna 2/3 van het natuurlijke broeikaseffect komt door de aanwezigheid van waterdamp in onze atmosfeer." En verder: "zonder broeikasgassen en met gelijke andere factoren (zoals de weerkaatsing van zonlicht) zou het gemiddeld op aarde 33 graden kouder zijn. Andere belangrijke broeikasgassen zijn koolstofdioxide en methaan." Tot zover het KNMI.

De meeste vulkaanuitbarstingen hebben een tijdelijk afkoelend effect, omdat de uitgestoten gassen kleine deeltjes bevatten (aerosolen) die het inkomende zonlicht weerkaatsen. De eruptie van de Hunga Tonga was echter totaal anders vanwege de enorme hoeveelheid uitgestoten waterdamp.

Over waterdamp als broeikasgas horen we heel weinig in de reguliere media, die zich meestal eenzijdig focussen op de menselijke uitstoot van koolstofdioxide. Boze tongen beweren dat je moeilijk een klimaatangst-hysterie kunt verkopen met "waterdamp" en je ook moeilijk een "waterdamp-taks" kunt invoeren. Maar dat zijn boze tongen.



Warme deken
Het belang van waterdamp als broeikasgas is heel goed merkbaar in woestijnen. Daar is bijna geen waterdamp aanwezig in de lucht. Daarom zal het daar 's avonds snel afkoelen, omdat de aarde de opwarming tijdens de dag via infraroodstraling 's nachts kan afvoeren richting heelal. In een vochtig tropisch klimaat zal de aanwezige waterdamp in de lucht deze infraroodstraling als een deken vasthouden. Het CO2-gehalte in woestijnen en tropen is gelijk. Het verschil van soms wel 30-40°C tussen dag en nacht in woestijnen komt uitsluitend door het ontbreken van het broeikaseffect van waterdamp. Ook bij ons is het broeikaseffect van waterdamp (wolken) goed merkbaar. Een nacht met bewolking is steeds warmer dan een nacht zonder wolken. De door de aarde uitgezonden infraroodstraling wordt door de waterdamp, aanwezig in de wolken, geabsorbeerd en vastgehouden en geeft dan "een warme deken".



Energiebudget
Het IPCC werkt met het concept van radiative forcing (RF) om het klimaat op aarde te beschrijven. De aarde als geheel is voor het IPCC een complex energiesysteem met inkomende energie (hoofdzakelijk van de zon) en uitgaande energie (infraroodstraling van de aarde). Deze twee tegengestelde energiestromen worden dan beïnvloed door wisselwerkingen met wolken, land en zee. Zoals weergegeven in onderstaande simpele illustratie van het energiebudget van de aarde. De energiestromen in de illustratie worden uitgedrukt in Watt/m2.


Kort door de bocht en heel eenvoudig samengevat kan men het IPCC-paradigma als volgt samenvatten: als het energiebudget van het systeem aarde in evenwicht is, dan is de globale gemiddelde temperatuur ook in evenwicht.

Verstoring
Voor veranderingen (verstoringen) in het energie-evenwicht van de aarde gebruikt het IPCC het concept RF als de netto verandering in de energiebalans van het aardsysteem als gevolg van een opgelegde verstoring. RF wordt ook uitgedrukt in energie-eenheid Watt per vierkante meter gemiddeld over een bepaalde periode, met als begin de "pre-industriële tijdsperiode. Om u een idee te geven is - volgens het IPCC - de huidige "verstoring" van het aardse energie-evenwicht door broeikasgassen netto ongeveer 2,72 Watt/m2. Vergeleken met de inkomende zonne-energie van 340 Watt/m2 is deze "verstoring" dus ongeveer 0,8%.

Voor het berekenen van deze netto verstoring van 2,72 Watt/m2 houdt het IPCC rekening met verschillende componenten. In het laatste IPCC-rapport AR 6 (Werkgroep 1 The Physical Science, Technical Summary) vinden we op pag. 92 het volgende overzicht waar waterdamp (hoewel het belangrijkste broeikasgas!) niet wordt vermeld.

Klimaatwetenschappers als prof. Happer (Princeton), prof. Lindzen (MIT) en prof. Koonin (NY) vinden dit theoretisch berekende broeikaseffect van 0,8% veel te klein als verklaring voor mogelijke klimaatverandering door het broeikaseffect van CO2.



Modellen negeren waterdamp
Waar blijft waterdamp in de IPCC-rapporten? Opvallend genoeg wordt waterdamp niet door het IPCC meegenomen als een radiative forcing in de klimaatmodellen. Wél alle andere bekende broeikasgassen en wisselwerkingen met aerosolen. Waarom het IPCC waterdamp niet meeneemt als radiative forcing - terwijl dat bij CO2 wel gebeurt - is eigenlijk het resultaat van een cirkelredenering. De IPCC-consensus is dat hoofdzakelijk één molecuul - namelijk CO2 - de regelknop voor het klimaat is. Vandaar dat alle klimaatmodellen zijn geprogrammeerd om uitkomsten te genereren op basis van verschillende CO2-niveaus.

De effecten van waterdamp (en van wolken) worden door de verschillende klimaatmodellen op verschillende manieren via parametrisatie meegenomen in hun complexe berekeningen. Dat is de reden waarom de verschillende klimaatmodellen zeer uiteenlopende uitkomsten geven. Ook de laatste zesde generatie CIMP6-klimaatmodellen (in theorie dus de meest geavanceerde en de beste) gaven dusdanig grote verschillen in temperatuurvoorspelling bij verdubbeling van CO2, dat zelfs het IPCC heeft geadviseerd om de "heetste" modellen maar niet te gebruiken.

De oorzaak van deze grote verschillen is hoe de feedback van waterdamp en wolken wordt meegenomen in de berekeningen. Het is letterlijk nattevingerwerk.



Versterkingsmechanisme
In de klimaatmodellen van het IPCC wordt het effect van het belangrijkste broeikasgas waterdamp als een feedback of versterkingsmechanisme meegenomen in de temperatuurberekeningen. Het IPCC bevestigt weldat waterdamp de grootste feedback geeft en dat het effect van de wolken de grootste onzekerheid is in de berekeningen van de klimaatmodellen. We lezen in het meest recente IPCC-rapport AR6 op pag. 95: The combined water vapour and lapse rate feedback makes the largest single contribution to global warming, whereas the cloud feedback remains the largest contribution to overall uncertainty.



Klimaat als onopgeloste puzzel
Prof. Bjorn Stevens is directeur van het Max Planck Instituut voor Meteorologie in Hamburg en een erkende wereldwijde expert op het gebied van wolken en klimaatmodellen. Hij bevestigt dat we nog steeds niet weten hoe wolken ons klimaat beïnvloeden. In het vaktijdschrift Nature of Geoscience schrijft hij, samen met elf andere top-klimaatwetenschappers uit USA, Frankrijk, UK , Japan en Australië: "de fundamentele puzzels van de klimaatwetenschap blijven onopgelost vanwege ons beperkte begrip van hoe wolken, circulatie en klimaat op elkaar inwerken. Een voorbeeld is ons onvermogen om robuuste beoordelingen te geven van toekomstige wereldwijde en regionale klimaatveranderingen.

Vanwege de vele nog niet opgeloste puzzels van de klimaatwetenschap en gezien het feit dat waterdamp het belangrijkste broeikaseffect veroorzaakt, kunnen we niet uitsluiten dat we sinds 15 januari 2022 genieten van Hunga-Tonga-weer.

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Tonga volcano triggered seafloor debris stampede

Last year's Tonga volcanic eruption produced the fastest underwater flows ever recorded, scientists say.

Huge volumes of rock, ash and mud were clocked moving across the ocean floor at speeds of up to 122km/h (75mph).

These "density currents", as they're known, snapped long sections of telecommunications cabling, cutting the Pacific kingdom's link to the global internet.

They also smothered and killed all sealife in their path.

It's another example of the prodigious scale of the 15 January eruption.

The underwater volcano called Hunga-Tonga Hunga-Ha'apai is already in the record books for:

the height of its eruption plume, which rose half way to space (58km) producing the biggest atmospheric disturbance in instrumented history triggering the most intense lightning storm - 2,600 flashes per minute

Scientists knew most of the roughly six cubic km of rock and ash thrown into the sky by the volcano must have come back down and spread out across the ocean floor, but now they've been able to map and measure its journey underwater and say something about its speed.

They did this by surveying and sampling the seafloor to see where the deposits went, and by comparing the timing of the eruption with the timing of the cable breaks.

There were two cables operational near the volcano, one connecting Tonga to the global internet and the other distributing this service to local islands.

The domestic cable, 50km from Hunga-Tonga, was the first to go down, 15 minutes after the onset of the main eruptive event. The international cable, some 70km away, followed about an hour later.

Researchers, led from the UK's National Oceanography Centre, say their investigations indicate the flow that broke the local submarine cable must have been moving at 73-122km/h (45-75mph); and even at the greater distance of the international cable, a velocity of 47-51km/h (29-32mph) is realistic.

"These flows hit the sweet spot for going as fast as they possibly could," said Dr Mike Clare, who is a co-lead author on a report in this week's Science Magazine.

"The rock and ash in the high eruption column fell down and went into the ocean like a jet. When this material hit the 40-degree slopes of the volcano flanks, it bit off chunks of the volcano and became even more dense. It walloped the domestic cable, was steered around corners and then walloped the international cable," he told the Science In Action programme on the BBC World Service.

https://twitter.com/NUnl/(...)GIFEINUU9VlfdXA&s=19

Nu dit onderwerp weer relevant werd in grote reeks
https://agupubs.onlinelib(...)10.1029/2023GL104634
https://agupubs.onlinelib(...)10.1029/2023GL104297
https://www.mdpi.com/2073-4433/15/4/483

Nieuwsartikel over het Australische onderzoek dat verwacht dat de impact op het klimaat 7 tot 8 jaar duurt:

https://www.abc.net.au/ne(...)an-weather/101978886

Het onderzoek zelf:

https://www.researchgate.net/publication/372889143_Long-term_surface_impact_of_Hunga_Tonga-Hunga_Ha'apai-like_stratospheric_water_vapor_injection

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New trigger proposed for record-smashing 2022 Tonga eruption

Fifteen minutes before the massive January 2022 eruption of the Hunga Tonga-Hunga Ha’apai volcano, a seismic wave was recorded by two distant seismic stations. Now, researchers argue that similar early signals could be used to warn of other impending eruptions in remote oceanic volcanoes.

The researchers propose that the seismic wave was caused by a fracture in a weak area of oceanic crust beneath the volcano’s caldera wall. That fracture allowed seawater and magma to pour into and mix together in the space above the volcano’s subsurface magma chamber, explosively kickstarting the eruption.

The research was published in Geophysical Research Letters, an open-access AGU journal that publishes high-impact, short-format reports with immediate implications spanning all Earth and space sciences.

The results build on the researchers’ previous work monitoring remote volcanoes. In this case, the Rayleigh wave, a type of seismic wave that moves through the Earth’s surface, was detected 750 kilometers (approximately 466 miles) from the volcano.

“Early warnings are very important for disaster mitigation,” said Mie Ichihara, a volcanologist at the University of Tokyo and one of the study’s coauthors. “Island volcanoes can generate tsunamis, which are a significant hazard.”

Silent precursor to a violent eruption
Hunga Tonga-Hunga Ha’apai is an oceanic volcano in the western Pacific Ocean in the Kingdom of Tonga. The seamount was created by the subduction of the Pacific Plate underneath the Australian Plate, a process that generates magma and leads to eruptions.

On January 15, 2022, the volcano erupted with record-breaking energy, injecting 58,000 Olympic swimming pools of water vapor into the stratosphere, setting off an unprecedented lightning storm and generating a tsunami. That massive eruption was preceded by a smaller eruption on January 14 and, before that, a month of eruptive activity.

Researchers still debate the exact start time of the eruption, though most agree that the eruption started shortly after 4:00 Coordinated Universal Time (UTC). The new study reports a Rayleigh wave that started around 3:45 UTC.

The researchers used seismic data to analyze the Rayleigh wave, which was detected by instruments, but not felt by humans, at seismic stations on the islands of Fiji and Futuna. While Rayleigh waves are a common feature of volcanic eruptions and earthquakes, the researchers believe that this wave signified a precursor event and possible cause of the massive eruption.

“Many eruptions are preceded by seismic activity,” said Takuro Horiuchi, a volcanology graduate student at the University of Tokyo and the lead author of the study. “However, such seismic signals are subtle and only detected within several kilometers of the volcano.”

In contrast, this seismic signal traveled a great distance, indicating a huge seismic event. “We believe unusually large movements started at the time of the precursor,” Horiuchi said.

Secrets of the seamount
Scientists may never know exactly what caused the gigantic, “caldera-forming” eruption, but Ichihara believes that the process was not instantaneous. Instead, she thinks that this precursor event was the start of an underground process that ultimately led to the eruption.

But it can be difficult to nail down the origins of these rare, colossal eruptions.

“There are very few observed caldera-forming eruptions, and there are even fewer witnessed caldera-forming eruptions in the ocean,” Ichihara said. “This gives one scenario about the processes leading to caldera formation, but I wouldn’t say that this is the only scenario.”

Regardless, detecting early eruption signals may give island nations and coastal areas more valuable time to prepare when faced with imminent tsunamis — even when the signal cannot be felt on the surface.

“At the time of the eruption, we didn’t think of using this kind of analysis in real-time,” Ichihara said. “But maybe the next time that there is a significant eruption underwater, local observatories can recognize it from their data.”