![Shock waves, landslides may have caused 'rare' volcano tsunami: experts](https://www.berlinertageblatt.de/media/shared/articles/1b/d7/0c/Shock-waves--landslides-may-have-ca-977952.jpg)
-
'Super proud' Sabalenka downs Pegula to win US Open thriller
-
In Papua New Guinea, Pope holds mass 'at the edge of the world'
-
Hewett stays positive for wheelchair tennis despite agonising defeat
-
Three things on US Open champion Aryna Sabalenka
-
Sabalenka downs Pegula to win US Open thriller
-
USA men land Paralympic basketball three-peat, Jiang takes 7th swim gold
-
USA slump to first home defeat against Canada in 67 years
-
Argentina hand Australia record 67-27 loss in Rugby Championship
-
England impress on Carsley bow, Germany, Dutch hit five
-
AFP photographer wins top prize for Gaza coverage
-
No Love for Packers for three weeks after ligament sprain: reports
-
Pedro Almodovar: chronicler of modern Spain crowned in Venice
-
Almodovar wins top Venice prize for end-of-life film
-
Trump sounds dark tone at rally, Harris 'ready' for debate
-
Wirtz and Musiala dazzle to kick-start new Germany era
-
Chinese teenager takes 7th gold of Paris Paralympics
-
England interim boss Carsley 'respects' divided opinions over anthem
-
Neuville moves to the front in the Acropolis Rally
-
Garfield, Pugh charm Toronto in new romance 'We Live in Time'
-
21 boys confirmed dead in Kenya school inferno
-
Over 100,000 protest in France against new prime minister
-
Golden 30 minutes takes China to swimming Paralympics swimming domination
-
Green leads Australia to T20 series sweep of Scotland
-
Nigeria, Cameroon win afer chaotic AFCON build-ups
-
Nicole Kidman: A-lister, cinematic chameleon, wins in Venice
-
'I had to prove myself', says Kolisi after win against All Blacks
-
Almodovar wins top prize at Venice film festival
-
Grealish savours England redemption after 'worst summer'
-
Carsley makes flying start as England interim boss in win over Ireland
-
Springboks close on Rugby Championship with storming win over All Blacks
-
Sri Lanka's De Silva and Kamindu Mendis defy England in third Test
-
Farrell's Racing lose on opening day of Top 14
-
Ireland and UK to 'reset' relations as Starmer visits Dublin
-
Dunbar takes second Vuelta stage as Roglic closes in on victory
-
Fritz eyes US Open glory to end 21 years of American hurt
-
Thousands protest in France against new prime minister
-
Death toll from Kenya school blaze rises to 21
-
Brazil's right rallies for 'freedom' after X suspended
-
Trump to hold rally in swing state, Harris preps for debate
-
Stone at the double as Sri Lanka collapse against England in third Test
-
French tennis player takes legal action over online abuse
-
Italy backs Kyiv's 'legitimate defence' as Zelensky presses allies
-
The Body Shop rescued from administration after deal
-
Martin roars to victory in San Marino sprint, extends MotoGP lead
-
Smoke and screams: The horror of Kenya's school dorm inferno
-
MotoGP leader Martin roars to victory in San Marino sprint
-
Ireland and UK to 'reset' relations as Starmer begins Dublin visit
-
Ma Lin turns brutal encounter with bear into glorious Paralympic career
-
Flintoff appointed England Lions head coach
-
Sri Lanka hit back as Pope falls during England collapse in second Test
![Shock waves, landslides may have caused 'rare' volcano tsunami: experts](https://www.berlinertageblatt.de/media/shared/articles/1b/d7/0c/Shock-waves--landslides-may-have-ca-977952.jpg)
Shock waves, landslides may have caused 'rare' volcano tsunami: experts
A rare volcano-triggered tsunami sparked by the eruption of Hunga Tonga-Hunga Ha'apai in Tonga could have been caused by shock waves or shifting underwater land, experts said Monday.
"A volcanic-source tsunami event is rare but not unprecedented," a post on the website for New Zealand's geological hazard monitoring system GNS said Monday.
GNS Tsunami Duty Officer Jonathan Hanson said it probably occurred in part thanks to a previous eruption of the same volcano one day earlier.
"It is likely that the earlier 14 January eruption blew away part of the volcano above water, so water flowed into the extremely hot vent," wrote Hanson.
"This meant that the Saturday evening eruption initially occurred underwater and exploded through the ocean, causing a widespread tsunami," he said.
Two days after Hunga Tonga-Hunga Ha'apai's massive explosion, the nation's 100,000 population remained virtually cut off from the rest of the world with crippled communications and stalled emergency relief efforts.
The volcano cloaked Tonga in a film of ash, sent a column of ash and gas 20 kilometres into the air and shock waves that could be seen from space rippling across the planet.
It also triggered a Pacific-wide tsunami whose waves were strong enough to drown two women in Peru more than 10,000 kilometres (6,000 miles) away.
- Ring of Fire -
Hunga Tonga-Hunga Ha'apai is located in the so-called Ring of Fire, where a rift between shifting tectonic plates results in increased seismic activity.
In a volcanic eruption, magma rising to the surface of the Earth's crust causes volcanic gases to be released that then push their way out from underground, creating pressure.
When the gases reach water it expands into water vapour, creating even more pressure.
Volcano expert Ray Cas of Monash University in Australia said he suspected the intensity of the explosion suggested a large amount of gas had risen into the vent.
"The tsunamis could have been triggered by shock waves propagating through water," he commented on the Australian Science Media Centre.
"But more likely largely by a landslide on the submarine part of the volcanic edifice triggered by the explosive eruption."
Yet another possibility is that the volcano's special location just beneath the surface of the ocean could have made its effects worse.
The volcano's 1,800 metres of height is almost entirely submerged beneath the surface of the ocean, the edge of its crater forming an uninhabited island.
"When eruptions happen deep in the ocean, the water tends to muffle the activity. When it happens in the air, the risks are concentrated to the immediate area," Paris-based geologist Raphael Grandin told AFP.
"But when it's just under the surface, that's when the tsunami risk is greatest," he said.
- Exceptionally loud eruption -
People are reported to have heard Hunga Tonga-Hunga Ha'apai's eruption as far away as Alaska, 9,000 kilometres from the source, which Grandin said is "exceptional".
"As far as I know the last explosion that was audible at that distance was caused by the Krakatoa volcano in Indonesia in 1883 -- it killed 36,000 people," he said.
Experts also said that while the volcano could experience further activity, past research shows an eruption of Saturday's scale probably only occurs every 1,000 years.
Scientists who commented on the phenomenon said they would know more about how it took place once communication with the Pacific nation of some 170 islands could be restored.
M.Ouellet--BTB