In late 2014 and early 2015, a series of eruptions in the area, about 60 kilometers north of the capital, created a small island and disrupted international flights to the Pacific archipelago for several days.
On Sunday, the Bureau of Meteorology issued renewed tsunami warnings and naval threats to the entire east coast of Australia, with lifeguards closing all beaches affected by the warning. NSW beaches remained closed Sunday night.
Meteorologist Sarah Scully said warnings are expected to be canceled Sunday night, with the highest wave recorded at 1.27 meters on Norfolk Island.
“So a huge amount of energy was released by the volcanic eruption and it was captured by the oceans,” she said, noting that a 0.82 meter wave was recorded on the Gold Coast and a 0.77 meter wave at Twofold Bay.
For a tsunami alert to be canceled, an area must have no significant wave height for six hours, Ms. Scully said.
The eruption generated huge waves on several islands in the South Pacific and triggered several global tsunami warnings, from New Zealand to the west coast of the United States and South America. Echoes could be felt in Mount Hood, Oregon, USA. An evacuation order was issued for California beaches, and waves hit Santa Cruz Harbor, which sank the boats and flooded parking lots.
From Bondi to Newport, many surfers chose to stay in the water, but Bondi’s Ironman series was canceled.
Coastal researcher Hannah Power from the University of Newcastle said geological evidence from massive eruptions shows that the events are not “usually one-off” and often come in multiples.
“Tsunami waves are coming in clusters,” said Associate Professor Power.
“We may see another eruption in days, weeks or even years. Often the first wave is not the biggest, so people can become complacent.
“The last time we saw tsunami waves like this big one hit Australia’s east coast was in 1960. The tsunami waves we’ve seen here have been about a meter high and everyone is thinking ‘well, I’m surfing or swimming in it’. But waves, we “Looking at our shoreline every day, arriving every 10 seconds. Tsunamis are different in that they arrive every 10 to 30 minutes.”
Dr. Power said powerful and unusual water currents were “pushed upstream into estuaries and then withdrawn downstream” while tsunami waves propagated in and out of the estuary system.
“Even as far as 8,000 kilometers away, on the west coast of the United States, we see significant damage from this event,” said Dr. Power and noticed that Tonga is sitting on the Ring of Fire in the Pacific Ocean, which is surrounded by a tectonic plate. borders where more than 90 percent of the world’s earthquake activity takes place.
The Tonga-Kermadec Tomb in the Western Pacific is a truly active part of the world where two tectonic plates meet. It is an area exposed to volcanoes and earthquakes, and an event could mean several months or years of more activity in the future. . “
New Zealand’s Prime Minister Jacinda Ardern said on Sunday that although there were no official reports of deaths or injuries, further volcanic activity could not be ruled out and the ash flags from the eruption had polluted Tonga’s water supply.
“We have … aircraft ready to deploy and are looking at deploying a naval vessel should the need arise,” she said.
“The clear view is that we want to be in Tonga on Earth as soon as we can. For flights that look like tomorrow. [By sea], we are already preparing to take these steps as we speak, ”said Mrs Ardern, noting that the satellite images brought the severity of the eruption and potential damage to the nearest islands. “We are able to implement within eight hours, but we need to know from the Tongan authorities what it is they need to ensure we deliver.”
Australia’s international development minister, Zed Seselja, said Prime Minister Scott Morrison and Mrs Ardern had spoken earlier on Sunday and agreed it was important that “Australia and New Zealand coordinate very closely in any response.”
“The Tongan government has agreed to an offer of assistance from the Australian government on a P8 surveillance flight, which we hope will be able to deploy [Monday] tomorrow, “said Mr Seselja.
In anticipation of ash and weather, the flight will assess damage to critical infrastructure such as roads, ports and power lines, which will determine the next phase of the response.
University of Auckland Professor Shane Cronin, a volcanologist, told New Zealand’s RNZ radio that the umbrella cloud from the explosion was 300 kilometers wide at one point.
“The cloud covered [nearest] island, therefore it became completely dark. The ash lets no light through, ”he said.
Professor Cronin said there would “almost certainly be more outbreaks” in the next few days and weeks.
ANU’s earthquake and tsunami researcher, Professor Phil Cummins, said that while Australia’s east coast had historically avoided major tsunamis, the number of southern volcanoes along the Tonga-Kermadec tomb poses risks.
“If that trench had a major earthquake or a volcanic flank collapse [then] which could cause a significant tsunami on Australia’s east coast. “
University of NSW Coastal Researcher Mitchell Harley said the one-meter-long tsunami waves that hit Sydney’s coasts over the weekend generated strong currents, making surfing and sailing dangerous.
“To the naked eye, it is not easy to see. But if you can imagine high and low tides coming up and down at hyper speed, that’s what’s happening. It’s not a huge wave, just a slow process, and it’s this acceleration that is causing strong rifts. ”
with AP and Mike Foley
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