three questions about the eruption of the volcano whose shock wave was recorded as far away as France

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A fungus of smoke and ashes 30 km high! Stunning views taken from space have shown the moment the Hunga Tonga-Hunga Ha’apai volcano erupted on Friday (January 14) on one of Tonga’s uninhabited islands, located about 65 km from the capital Nuku’alofa . The cloud spread out into the lower stratosphere with a diameter of over 450 kilometers.

The eruption lasted eight minutes, and was so loud it was heard “like a sound of distant thunder” on the Fiji Islands, more than 800 km away, according to officials in the Fijian capital, Suva. It also caused tsunamis that flooded coasts from Japan to the United States, and killed two people in Peru. Franceinfo looks back on this disaster which deprives the Tonga archipelago of telephone and internet connections for several weeks.

1What is the damage on site?

New Zealand Prime Minister Jacinda Ardern, said Sunday his government had established satellite contact with the country’s high commission in Nuku’alofa. No casualties were reported in Tonga’s capital, she says, but there is damage “important” in some areas.

On Monday evening, the family of Angela Glover, a 50-year-old Briton, announced that she had been swept away by the tsunami in Tonga after trying to rescue dogs from her shelter, reports the BBC. This is the first death recorded in the country.

“A 1.20 m tsunami was observed in Nuku’alofa”, the country’s capital, the Australian Bureau of Meteorology announced. “The tsunami had a significant impact on the northern shoreline of Nuku’alofa, with boats and large rocks washed ashore”, reported Jacinda Ardern, without specifying whether there had been damage in the other islands of the archipelago. The Pacific Tsunami Warning Center (PTWC) said at 3 a.m. GMT (4 a.m. in France) that the tidal wave threat was “generally past” for countries bordering the ocean.

This eruption severed an underwater communication cable and could deprive the archipelago of internet for “two weeks”, said the Director of Networks of the Southern Cross Cable Network. This company assists Tonga Cable Limited, owner of the 872 kilometer cable linking Tonga to Fiji and from there to the rest of the world. Initially, the internet outage was attributed to a power outage caused by the powerful eruption, but tests conducted after power was restored revealed a broken cable.

The relief of the Tongan archipelago has also been modified. Islands have completely disappeared, others have been swallowed up, reports the Futura-sciences site. In particular that born in 2014 from a previous eruption of the same volcano. Today, “The island born in 2014 literally exploded. This implies that what was under the island also disappeared, and that is what caused the tsunami”, advances to New Caledonia The 1st Jérôme Aucan, Director of the Pacific Community Center for Ocean Science.

2Did the eruption have repercussions elsewhere on the globe?

The eruption, one of the most powerful in recent decades in the world, was heard as far away as Alaska. It triggered a tsunami that flooded the coasts of the United States to Chile and Japan. Ash and acid rain battered much of the Pacific.

More than 10,000 kilometers from the site of the eruption, in Peru, two women died by drowning on the beach of Naylamp, in Lambayeque, in the North, due to “abnormal waves” from the eruption in Tonga, the local National Emergency Operations Center said on Sunday. The day before, Peru had closed 22 ports as a precaution. The police had rescued 23 people on the coast.

In Chile, the National Emergency Situations Office had warned of the possibility that a “minor tsunami” does not reach Easter Island and other Chilean archipelagos. In the United States, the West Coast and Hawaii were affected by minor flooding. “The main impacts expected are strong rip currents and flooding of coasts and low-lying areas”, had warned the weather service. The American Geological Institute (USGS) has recorded the eruption as equivalent to a magnitude 5.8 earthquake at zero depth.

3Why was the tremor felt as far away as France?

The wave of the eruption was recorded in France, more than 17,000 km away. In Paris, it arrived in two stages. A first clear variation in atmospheric pressure was observed on Saturday between 8 p.m. and 9 p.m., a second in the night from Saturday to Sunday between 2 a.m. and 3 a.m.

Elsewhere in France, some meteorological stations such as those in the Var “recorded the sharp variations in atmospheric pressure following the shock wave from the eruption of the volcano in the Tonga Islands, which occurred around 6:10 a.m. French time this day”, wrote the Facebook account Météo varoise on Saturday, adding that “many other weather stations in Western Europe have recorded these variations”.

“It’s very impressive, but you have to imagine that in 1883, the wave of the eruption of Krakatoa in Indonesia had circled the planet seven times.”

Philipson Bani, volcanologist at the Development Research Institute

at La1ere

“We used to say that it is the equivalent of 10,000 atomic bombs”, compare for New Caledonia The 1st Philipson Bani, volcanologist at the Research Institute for Development (IRD). “According to the first scientific studies that came out this Sunday morning, it is a sequence that occurs every 1,000 years”, adds Jérôme Aucan.


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