Tag Archives: Tsunamis

World

Tonga: Tsunami warning issued after 7.9 magnitude earthquake

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CNN
 — 

The government of the island nation of Tonga called for an immediate evacuation inland on Friday following what it said was a 7.9 magnitude earthquake that triggered a tsunami warning.

“A strong earthquake has occurred near Tonga and felt in whole of Tonga. A dangerous tsunami could occur in minutes,” the government said in a statement on its website.

“You are advised to evacuate immediately inland to high ground or to the 3rd level of a steel or concrete building until the threat has passed. Mariners are advised to move to deep ocean away from reefs,” it said.

The Tonga government said the earthquake occurred at a depth of 10 kilometers (6.2 miles) about 200 kilometers (124 miles) east of the city of Neiafu, on the island of Vava’u.

The United States Geological Survey (USGA) said Friday a 7.3 magnitude earthquake had been detected 211 kilometers east of Neiafu, Tonga.

Earlier this year, Tonga was hit by a record-breaking eruption from an underwater volcano, which released a huge plume of ash, gas and steam up to 20 kilometers into the atmosphere and sent tsunami waves rolling across the Pacific.

The main island, Tongatapu, suffered significant damage from the tsunami and was smothered in a thick layer of ash.

At least two deaths were reported at the time.

This is a breaking news story. More to follow.

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Science

Asteroid that wiped out the dinosaurs also triggered a global tsunami

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CNN
 — 

When a city-size asteroid slammed into Earth 66 million years ago, it wiped out the dinosaurs – and sent a monster tsunami rippling around the planet, according to new research.

The asteroid, about 8.7 miles (14 kilometers) wide, left an impact crater about 62 miles (100 kilometers) across near Mexico’s Yucatan peninsula. In addition to ending the reign of the dinosaurs, the direct hit triggered a mass extinction of 75% of animal and plant life on the planet.

When the asteroid hit, it created a series of cataclysmic events. Global temperatures fluctuated; plumes of aerosol, soot and dust filled the air; and wildfires started as flaming pieces of material blasted from the impact re-entered the atmosphere and rained down. Within 48 hours, a tsunami had circled the globe – and it was thousands of times more energetic than modern tsunamis caused by earthquakes.

Researchers set out to gain a better understanding of the tsunami and its reach through modeling. They found evidence to support their findings about the path and power of the tsunami by studying 120 ocean sediment cores from across the globe. A study detailing the findings published Tuesday in the journal American Geophysical Union Advances.

It’s the first global simulation of the tsunami caused by the Chicxulub impact to be published in a peer-reviewed scientific journal, according to the authors.

The tsunami was powerful enough to create towering waves more than a mile high and scour the ocean floor thousands of miles away from where the asteroid hit, according to the study. It effectively wiped away the sediment record of what happened before the event, as well as during it.

“This tsunami was strong enough to disturb and erode sediments in ocean basins halfway around the globe, leaving either a gap in the sedimentary records or a jumble of older sediments,” said lead author Molly Range, who began working on the study as an undergraduate student and completed it for her master’s thesis at the University of Michigan.

Researchers estimate that the tsunami was up to 30,000 times more energetic than the December 26, 2004 Indian Ocean tsunami, one of the largest on record, that killed more than 230,000 people. The energy of the asteroid impact was at least 100,000 times larger than the Tonga volcanic eruption earlier this year.

Brandon Johnson, study coauthor and an associate professor at Purdue University, used a large computer program called a hydrocode to simulate the first 10 minutes of the Chicxulub impact, including the formation of the crater and the beginning of the tsunami.

He included the size of the asteroid and its speed, which was estimated to be moving at 26,843 miles per hour (43,200 kilometers per hour) when it hit the granite crust and shallow waters of the Yucatan peninsula.

Less than three minutes later, rocks, sediments and other debris pushed a wall of water away from the impact, creating a 2.8 mile (4.5 kilometer) tall wave, according to the simulation. This wave subsided as exploded material fell back to Earth.

But as the debris fell, it created even more chaotic waves.

Ten minutes after impact, a ring-shaped wave about a mile high began traveling across the ocean in all directions from a point that was located 137 miles (220 kilometers) away from the impact.

This simulation was then entered into two different global tsunami models, MOM6 and MOST. While MOM6 is used to model deep ocean tsunamis, MOST is part of tsunami forecasting at the National Oceanic and Atmospheric Administration’s Tsunami Warning Centers.

Both models delivered almost the exact same results, creating a timeline of the tsunami for the research team.

An hour after impact, the tsunami had travel beyond the Gulf of Mexico into the North Atlantic Ocean. Four hours post-impact, the waves passed through the Central American Seaway and into the Pacific Ocean. The Central American Seaway once separated North and South America.

Within 24 hours, the waves entered the Indian Ocean from both sides after traveling across the Pacific and Atlantic oceans. And by 48 hours after impact, large tsunami waves had reached most of Earth’s coastlines.

The underwater current was strongest in the North Atlantic Ocean, the Central American Seaway and the South Pacific Ocean, exceeding 0.4 miles per hour (643 meters per hour), which is strong enough to blast away sediments on the ocean floor.

Meanwhile, the Indian Ocean, North Pacific, the South Atlantic and the Mediterranean were shielded from the worst of the tsunami, with lesser underwater currents.

The team analyzed information from 120 sediments that largely came from previous scientific ocean-drilling projects. There were more intact sediment layers in the waters protected from the tsunami’s wrath. Meanwhile, there were gaps in the sediment record for the North Atlantic and South Pacific oceans.

The researchers were surprised to find that sediment on the eastern shores of New Zealand’s north and south islands had been heavily disturbed with multiple gaps. Initially, scientists thought this was because of the activity of tectonic plates.

But the new model shows the sediments being directly in the pathway of the Chicxulub tsunami, despite being 7,500 miles (12,000 kilometers) away.

“We feel these deposits are recording the effects of the impact tsunami, and this is perhaps the most telling confirmation of the global significance of this event,” Range said.

While the team didn’t estimate the tsunami’s impact on coastal flooding, the model shows that the North Atlantic coastal regions and South America’s Pacific coast were likely hit with waves taller than 32.8 feet (20 meters). The waves only grew as they neared the shore, causing flooding and erosion.

Future research will model the extent of global flooding after the impact and how far inland the tsunami’s effects could be felt, according to study coauthor and University of Michigan professor and physical oceanographer Brian Arbic.

“Obviously the greatest inundations would have been closest to the impact site, but even far away the waves were likely to be very large,” Arbic said.

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World

Long COVID-free, isolated Pacific islands hit with outbreaks

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BANGKOK (AP) — For more than two years, the isolation of the Pacific archipelago nation of Tonga helped keep COVID-19 at bay.

But last month’s volcanic eruption and tsunami brought outside deliveries of desperately needed fresh water and medicine — and the virus.

Now the country is in an open-ended lockdown, which residents hope will help contain the small outbreak and will not last too long.

“We have pretty limited resources, and our hospitals are pretty small,” Tongan business owner Paula Taumoepeau said Friday. “But I’m not sure any health system can cope. We are lucky we’ve had two years to get our vax rate pretty high, and we had a pretty immediate lockdown.”

Tonga is only one of several Pacific countries to experience their first outbreaks over the past month. All have limited health care resources, and there is concern that the remoteness that once protected them may now make helping them difficult.

“Clearly when you’ve got countries that have already got a very stretched, and fragile health system, when you have an emergency or a disaster and then you have the potential introduction of the virus, that’s going to make an already serious situation immeasurably worse,” said John Fleming, the Asia-Pacific head of health for the Red Cross.

Tonga was coated with ash following the Jan. 15 eruption of the massive undersea Hunga Tonga Hunga Ha’apai volcano, then hit with a tsunami that followed.

Only three people have been confirmed killed, but several small settlements in outlying islands were wiped off the map and the volcanic ash tainted much of the drinking water.

The nation of 105,000 had reported only one case of COVID-19 since the beginning of the pandemic — a Church of Jesus Christ of Latter-day Saints missionary returning to the island from Africa via New Zealand who tested positive in October — and authorities debated whether to let international aid in.

They decided they had to, but despite strict precautions unloading ships and planes from Australia, New Zealand, Japan, Britain and China, two Tongan men who worked at the capital’s Queen Salote Wharf handling shipments tested positive on Tuesday.

“Tonga is just out of luck this year,” said Samieula Fonua, the chairman of Tonga Cable Ltd., the state-own company that owns the sole fiber-optic cable connecting the nation to the rest of the world. “We desperately need some good news.”

The two were moved into isolation, but in tests of 36 possible contacts, one’s wife and two children also tested positive, while the others tested negative, the local Matangi Tonga news site reported.

It was not clear how many people might have come into contact with the dockworkers, but the government released a list of locations where the virus could have spread, including a church, several shops, a bank and a kindergarten.

Prime Minister Siaosi Sovaleni imposed an open-ended lockdown starting 6 p.m. on Wednesday. It could be particular arduous for Tongans because most have been without any internet connections since the volcanic eruption severed the fiber optic cable to the country.

One of the infected dock workers has since tested negative, but remains in quarantine, and 389 others have been cleared of COVID-19, Sovaleni told reporters in Tonga. But he said Friday that a primary contact to one of the people infected had tested positive, and ordered the lockdown extended another 48 hours.

The government has been primarily communicating with residents by radio addresses, and Fonua said his crews estimate they may have to replace an 87-kilometer (54 mile) section of undersea cable. They were hoping to restore service by next week.

It is not yet known what variant of the virus has reached Tonga, nor who brought it in. Officials have stressed that the aid deliveries were tightly controlled, and that it is not yet proven the virus came in that way.

Sailors aboard the Australian aid ship HMAS Adelaide reported nearly two dozen infections after an outbreak on board, but authorities said it had been unloaded at a different wharf. Crew members aboard aid flights from Japan and Australia also reported infections.

“The people are OK with the lockdown because they understand the reason why, so the corona doesn’t spread over our little country,” Tulutulu Kalaniuvalu, a 53-year-old former police official who runs a business, told The Associated Press. He added that most Tongans depend on crops they grow on plantations and hope the lockdown is short-lived.

Experience from elsewhere, especially with the prevalence of the rapidly spreading omicron variant, suggests that Tonga faces an uphill battle in trying to contain the outbreak, Indonesian epidemiologist Dicky Budiman told the AP.

Some 61% of Tongans are fully vaccinated, according to Our World in Data, but because the country has not yet seen any infections, there’s no natural immunity and it is not clear whether the shots were given long enough ago that they may now be less effective, Budiman said.

He recommended that the government immediately start offering booster shots and open vaccinations to younger children.

“If we race with this virus we will not win,” he said in an interview from Australia. “So we have to move forward by protecting the most vulnerable.”

The October case of the missionary with COVID-19 prompted a wave of vaccinations, and 1,000 people already showed up for a first dose after the current outbreak was detected, Kalaniuvalu said.

Solomon Islands reported its first community outbreak on Jan. 19. With only 11% of its population fully vaccinated, the virus has been spreading rapidly with the Red Cross reporting that less than two weeks later, there are now more than 780 recorded cases and five COVID-19 related deaths.

Elsewhere, Fiji — still reeling from damage caused by Cyclone Cody in early January — has been battling an ongoing spike in cases, fueled by omicron, and cases have been reported for the first time in Kiribati, Samoa and Palau.

Palau has nearly its entire population fully vaccinated, while Fiji has 68% and Samoa 62%, but Kiribati is only at 33%.

The key to ensuring hospitals aren’t overwhelmed is to make sure more people get shots, Budiman said.

“These countries that choose to have this COVID-free strategy, they are very vulnerable,” he said.

Kalaniuvalu said some people have questioned the decision to let the ships carrying aid in to Tonga, but most feel it was necessary to help through the aftermath of the volcano and tsunami, and that the islanders now just had to do their best to minimize the impact of the outbreak.

“To be honest with you, we were one of the luckiest countries in the world for almost three years, now it’s finally here in Tonga,” he said.

“We, the people of Tonga, knew sooner or later the coronavirus would come to Tonga because the corona is here to stay.”

___ Perry reported from Wellington, New Zealand.

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World

Volcanic ash delays aid to Tonga as scale of damage emerges

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WELLINGTON, New Zealand (AP) — Thick ash on an airport runway was delaying aid deliveries to the Pacific island nation of Tonga, where significant damage was being reported days after a huge undersea volcanic eruption and tsunami.

New Zealand’s military is sending much-needed drinking water and other supplies, but said the ash on the runway will delay the flight at least a day. A towering ash cloud since Saturday’s eruption had prevented earlier flights. New Zealand is also sending two navy ships to Tonga that will leave Tuesday and pledged an initial 1 million New Zealand dollars ($680,000) toward recovery efforts.

Australia also sent a navy ship from Sydney to Brisbane to prepare for a support mission if needed.

Communications with Tonga have been extremely limited, but New Zealand and Australia sent military surveillance flights to assess the damage on Monday.

U.N. humanitarian officials and Tonga’s government “report significant infrastructural damage around Tongatapu,” U.N. spokesman Stephane Dujarric said.

“There has been no contact from the Ha’apai Group of islands, and we are particularly concerned about two small low-lying islands — Mango and Fonoi — following surveillance flights confirming substantial property damage,” Dujarric said.

New Zealand’s High Commission in Tonga also reported “significant damage” along the western coast of the main island of Tongatapu, including to resorts and along the waterfront area.

Satellite images captured the spectacular eruption, with a plume of ash, steam and gas rising like a giant mushroom above the South Pacific. Tsunami waves of about 80 centimeters (2.7 feet) crashed into Tonga’s shoreline, and crossed the Pacific, causing minor damage from New Zealand to Santa Cruz, California. The eruption set off a sonic boom that could be heard as far away as Alaska.

Two people drowned in Peru, which also reported an oil spill after waves moved a ship that was transferring oil at a refinery.

New Zealand’s Acting High Commissioner for Tonga, Peter Lund, said there were unconfirmed reports of up to three fatalities on Tonga so far.

One death has been confirmed by family: British woman Angela Glover, 50, who was swept away by a wave.

Nick Eleini said his sister’s body had been found and that her husband survived. “I understand that this terrible accident came about as they tried to rescue their dogs,” Eleini told Sky News. He said it had been his sister’s life dream” to live in the South Pacific and “she loved her life there.”

The explosion of the Hunga Tonga Hunga Ha’apai volcano, about 64 kilometers (40 miles) north of Nuku’alofa, was the latest in a series of dramatic eruptions. In late 2014 and early 2015, eruptions created a small new island and disrupted air travel to the Pacific archipelago.

Earth imaging company Planet Labs PBC had watched the island after a new vent began erupting in late December. Satellite images showed how drastically the volcano had shaped the area, creating a growing island off Tonga.

The U.N. World Food Program is exploring how to bring in relief supplies and more staff and has received a request to restore communication lines in Tonga, Dujarric said.

One complicating factor is that Tonga has managed to avoid outbreaks of COVID-19. New Zealand said its military staff were vaccinated and willing to follow Tonga’s protocols.

New Zealand’s military said it hoped the airfield in Tonga would be opened either Wednesday or Thursday. The military said it had considered an airdrop but that was “not the preference of the Tongan authorities.”

Communications with the island nation is limited because the single underwater fiber-optic cable that connects Tonga to the rest of the world was likely severed in the eruption. The company that owns the cable and repairs could take weeks.

Samiuela Fonua, who chairs the board at Tonga Cable Ltd., said the cable appeared to have been severed about 10 to 15 minutes after the eruption. He said the cable lies atop and within coral reef, which can be sharp.

Fonua said a ship would need to pull up the cable to assess the damage and then crews would need to fix it. A single break might take a week to repair, he said, while multiple breaks could take up to three weeks. He added that it was unclear yet when it would be safe for a ship to venture near the undersea volcano to undertake the work.

A second undersea cable that connects the islands within Tonga also appeared to have been severed, Fonua said. However, a local phone network was working, allowing Tongans to call each other. But he said the lingering ash cloud was continuing to make even satellite phone calls abroad difficult.

___

Associated Press journalist Jill Lawless in London contributed to this report.



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World

Volcano erupts in Pacific, West Coast under tsunami advisory

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WELLINGTON, New Zealand (AP) — An undersea volcano erupted in spectacular fashion near the Pacific nation of Tonga on Saturday, sending large tsunami waves crashing across the shore and people rushing to higher ground. A tsunami advisory was in effect for Hawaii, Alaska and the U.S. Pacific coast, with reports of waves pushing boats up in the docks in Hawaii.

There were no immediate reports of injuries or the extent of the damage because all internet connectivity with Tonga was lost at about 6:40 p.m. local time — about 10 minutes after problems began, said Doug Madory, director of internet analysis for the network intelligence firm Kentik.

Tonga gets its internet via an undersea cable from Suva, Fiji, which presumably was damaged. The company that manages that connection, Southern Cross Cable Network, could not immediately be reached for comment.

In Hawaii, the Pacific Tsunami Warning Center reported waves slamming ashore from half a meter (1.6 feet) in Nawiliwili, Kauai, to 80 centimeters (2.7 feet) in Hanalei. “We are relieved that there is no reported damage and only minor flooding throughout the islands,” the center said, describing the situation in Hawaii.

On Tonga, home to about 105,000 people, video posted to social media showed large waves washing ashore in coastal areas, swirling around homes and buildings, including a church. Satellite images showed a huge eruption, a plume of ash, steam and gas rising like a mushroom above the blue Pacific waters.

New Zealand’s military said it was monitoring the situation and remained on standby, ready to assist if asked.

The Tonga Meteorological Services said a tsunami warning was declared for all of the archipelago, and data from the Pacific tsunami center showed waves of 80 centimeters (2.7 feet) had been detected.

The explosion of the Hunga Tonga Hunga Ha’apai volcano was the latest in a series of spectacular eruptions.

A Twitter user identified as Dr. Faka’iloatonga Taumoefolau posted video showing waves crashing ashore.

“Can literally hear the volcano eruption, sounds pretty violent,” he wrote, adding in a later post: “Raining ash and tiny pebbles, darkness blanketing the sky.”

In Hawaii, Alaska and along the U.S. Pacific coast, residents were asked to move away from the coastline to higher ground and pay attention to specific instructions from their local emergency management officials, said Dave Snider, tsunami warning coordinator for the National Tsunami Warning Center in Palmer, Alaska.

The first waves to hit the continental United States were measured at about 30 centimeters (1 foot) in Nikolski, Atka and Adak, Alaska. The wave was about 20 centimeters (.7 feet) at Monterey, California, the U.S. National Tsunami Warning Center said in a tweet.

The National Weather Service said there are reports of waves pushing boats in Hawaii. Sea level fluctuations were also beginning in Alaska and California, according to the National Tsunami Warning Center.

Beaches and piers were closed across Southern California as a precaution but the National Weather Service tweeted there were “no significant concerns about inundation.” Strong rip currents were possible, however, and officials warned people to stay out of the water.

Crowds gathered at the Santa Cruz harbor early Saturday to watch water slowly rise and fall, straining boat ties on docks. There was no obvious immediate damage. In 2011, after the Japanese earthquake and tsunami, a series of surges cost $20 million of damage in the harbor.

“We don’t issue an advisory for this length of coastline as we’ve done — I’m not sure when the last time was — but it really isn’t an everyday experience,” Snider said. “I hope that elevates the importance and severity for our citizens.”

He said the waves already slamming ashore in Hawaii were just under the criteria for a more serious tsunami warning.

“The important thing here is the first wave may not be the largest. We could see this play out for several hours,” he added. “It looks like everything will stay below the warning level but it’s difficult to predict because this is a volcanic eruption and we’re set up to measure earthquake or seismic-driven sea waves.”

Residents of American Samoa were alerted of the tsunami warning by local broadcasters as well as church bells that rang territory-wide. An outdoor siren warning system was out of service. Those living along the shoreline quickly moved to higher ground.

As night fell, there were no reports of any damage and the Hawaii-based tsunami center canceled the alert.

Authorities in the nearby island nations of Fiji and Samoa also issued warnings, telling people to avoid the shoreline due to strong currents and dangerous waves. The Japan Meteorological Agency said there may be a slight swelling of the water along the coast, but it was not expected to cause any damage.

Tonga’s Islands Business news site reported that a convoy of police and military troops evacuated King Tupou VI from his palace near the shore. He was among the many residents who headed for higher ground.

Earlier, the Matangi Tonga news site reported that scientists observed massive explosions, thunder and lightning near the volcano after it started erupting early Friday. Satellite images showed a 5-kilometer (3 mile) -wide plume rising into the air to about 20 kilometers (12 miles).

More than 2,300 kilometers (1,400 miles) away in New Zealand, officials were warning of storm surges from the eruption.

The National Emergency Management Agency said some parts of New Zealand could expect “strong and unusual currents and unpredictable surges at the shore following a large volcanic eruption.”

New Zealand’s private forecaster Weather Watch tweeted that people as far away as Southland, the country’s southernmost region, reported hearing sonic booms from the eruption. Others reported that many boats were damaged by a tsunami that hit a marina in Whangarei, in the Northland region.

The volcano is located about 64 kilometers (40 miles) north of the capital, Nuku’alofa. Back in late 2014 and early 2015, a series of eruptions in the area created a small new island and disrupted international air travel to the Pacific archipelago for several days.

There is not a significant difference between volcanoes underwater and on land, and underwater volcanoes become bigger as they erupt, at some point usually breaching the surface, said Hans Schwaiger, a research geophysicist with the Alaska Volcano Observatory.

With underwater volcanoes, however, the water can add to the explosivity of the eruption as it hits the lava, Schwaiger added.

Before an explosion, there is generally an increase in small local earthquakes at the volcano, but depending on how far it is from land, that may not be felt by residents along the shoreline, Schwaiger said.

In 2019, Tonga lost internet access for nearly two weeks when the same fiber-optic cable was severed . The director of the local cable company said at the time that a large ship may have cut the cable by dragging an anchor. Until limited satellite access was restored people couldn’t even make international calls.

___

Associated Press writers Jennifer McDermott in Providence, Rhode Island, Frank Bajak in Boston, Mari Yamaguchi in Tokyo and Fili Sagapolutele in Pago Pago, American Samoa, contributed to this report.

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Science

Supermassive black holes could host giant, swirling gas ‘tsunamis’

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This artist’s visualization shows a supermassive black hole surrounded by dust and gas forming tsunamis on its outer edges.  (Image credit: Illustration by Nima Abkenar)

Could gas escaping the gravitational grasp of supermassive black holes be forming “tsunamis” in space? 

In a new, NASA-funded study, astrophysicists used computer simulations to model the environment around supermassive black holes in deep space. They found that there could be massive, tsunami-like structures forming near these black holes that are essentially massive, swirling walls of gas that have narrowly escaped the intense gravitational pull of the black hole. They even think that supermassive black holes could host the largest tsunami-like structures in the universe. 

“What governs phenomena here on Earth are the laws of physics that can explain things in outer space and even very far outside the black hole,” Daniel Proga, an astrophysicist at the University of Las Vegas, Nevada (UNLV), said in a NASA statement. 

Gallery: Black Holes of the Universe

This artist’s visualization shows a supermassive black hole surrounded by dust and gas forming tsunamis on its outer edges. The added close-ups show the tsunamis in more detail.  (Image credit: Illustration by Nima Abkenar)

In this study, researchers took a close look at the strange environment around supermassive black holes and how gases and radiation interact there.

Supermassive black holes sometimes have large disks of gas and matter that swirl around them, feeding them over time in a combined system known as an active galactic nucleus. These systems, which often shoot out jets of material, emit bright, shining X-rays above the disk, just out of gravitational reach of the black hole. This X-ray radiation pushes winds that stream out of the center of the system. This is called an “outflow.” 

This X-ray radiation could also help to explain denser, gaseous regions in the environment around supermassive black holes called “clouds,” the researchers think.

“These clouds are 10 times hotter than the surface of the sun and moving at the speed of the solar wind, so they are rather exotic objects that you would not want an airplane to fly through,” lead author Tim Waters, a postdoctoral researcher at UNLV who is also a guest scientist at Los Alamos National Laboratory in New Mexico, said in the same statement. 

The team showed with computer simulations how, far enough away from the black hole to be outside of its reach, the atmosphere of the disk spinning around the black hole can start to form waves of gas and matter. With the addition of the outflow winds that are pushed out by X-ray radiation, these waves can grow into massive tsunamis. These swirling waves of gas can stretch up to 10 light-years above the disk, the researchers found. Once these tsunami-like structures form, they are no longer under the influence of the black hole’s gravity, according to the statement. 

In these simulations, the researchers showed how bright X-ray radiation close to a black hole seeps into pockets of hot gas in the outer atmosphere of the disk. These bubbles of hot plasma expand into nearby, cooler gas at the edges of the disk, helping to spur the tsunami-like structures. The bubbles also block the outflow wind and spiral off into separate structures up to a light-year in size. These side structures are known as Kármán vortex streets, which are weather patterns that also occur on Earth (though on Earth, this pattern of swirling vortexes looks quite different.) 

Kármán vortex streets are named for the Hungarian-American physicist Theodore von Kármán, whose name also marks the boundary between Earth’s atmosphere and space.

This research goes against previous theories that have suggested that clouds of hot gas near an active galactic nucleus form spontaneously because of fluid instability, according to the statement. This study also contradicts the previous notion that magnetic fields are necessary to move cooler gas from a disk around a supermassive black hole. 

While no satellites currently operational can confirm their work, the team hopes to bolster their findings with future research and hopefully telescopic observations. Additionally, observations of plasma near active galactic nuclei from NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM-Newton space telescope are consistent with this team’s findings, according to the statement from NASA.

This work was published June 15 in the Astrophysical Journal.

Email Chelsea Gohd at cgohd@space.com or follow her on Twitter @chelsea_gohd. Follow us on Twitter @Spacedotcom and on Facebook.

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Science

Supermassive black holes could host giant, swirling gas ‘tsunamis’

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This artist’s visualization shows a supermassive black hole surrounded by dust and gas forming tsunamis on its outer edges.  (Image credit: Illustration by Nima Abkenar)

Could gas escaping the gravitational grasp of supermassive black holes be forming “tsunamis” in space? 

In a new, NASA-funded study, astrophysicists used computer simulations to model the environment around supermassive black holes in deep space. They found that there could be massive, tsunami-like structures forming near these black holes that are essentially massive, swirling walls of gas that have narrowly escaped the intense gravitational pull of the black hole. They even think that supermassive black holes could host the largest tsunami-like structures in the universe. 

“What governs phenomena here on Earth are the laws of physics that can explain things in outer space and even very far outside the black hole,” Daniel Proga, an astrophysicist at the University of Las Vegas, Nevada (UNLV), said in a NASA statement. 

Gallery: Black Holes of the Universe

This artist’s visualization shows a supermassive black hole surrounded by dust and gas forming tsunamis on its outer edges. The added close-ups show the tsunamis in more detail.  (Image credit: Illustration by Nima Abkenar)

In this study, researchers took a close look at the strange environment around supermassive black holes and how gases and radiation interact there.

Supermassive black holes sometimes have large disks of gas and matter that swirl around them, feeding them over time in a combined system known as an active galactic nucleus. These systems, which often shoot out jets of material, emit bright, shining X-rays above the disk, just out of gravitational reach of the black hole. This X-ray radiation pushes winds that stream out of the center of the system. This is called an “outflow.” 

This X-ray radiation could also help to explain denser, gaseous regions in the environment around supermassive black holes called “clouds,” the researchers think.

“These clouds are 10 times hotter than the surface of the sun and moving at the speed of the solar wind, so they are rather exotic objects that you would not want an airplane to fly through,” lead author Tim Waters, a postdoctoral researcher at UNLV who is also a guest scientist at Los Alamos National Laboratory in New Mexico, said in the same statement. 

The team showed with computer simulations how, far enough away from the black hole to be outside of its reach, the atmosphere of the disk spinning around the black hole can start to form waves of gas and matter. With the addition of the outflow winds that are pushed out by X-ray radiation, these waves can grow into massive tsunamis. These swirling waves of gas can stretch up to 10 light-years above the disk, the researchers found. Once these tsunami-like structures form, they are no longer under the influence of the black hole’s gravity, according to the statement. 

In these simulations, the researchers showed how bright X-ray radiation close to a black hole seeps into pockets of hot gas in the outer atmosphere of the disk. These bubbles of hot plasma expand into nearby, cooler gas at the edges of the disk, helping to spur the tsunami-like structures. The bubbles also block the outflow wind and spiral off into separate structures up to a light-year in size. These side structures are known as Kármán vortex streets, which are weather patterns that also occur on Earth (though on Earth, this pattern of swirling vortexes looks quite different.) 

Kármán vortex streets are named for the Hungarian-American physicist Theodore von Kármán, whose name also marks the boundary between Earth’s atmosphere and space.

This research goes against previous theories that have suggested that clouds of hot gas near an active galactic nucleus form spontaneously because of fluid instability, according to the statement. This study also contradicts the previous notion that magnetic fields are necessary to move cooler gas from a disk around a supermassive black hole. 

While no satellites currently operational can confirm their work, the team hopes to bolster their findings with future research and hopefully telescopic observations. Additionally, observations of plasma near active galactic nuclei from NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM-Newton space telescope are consistent with this team’s findings, according to the statement from NASA.

This work was published June 15 in the Astrophysical Journal.

Email Chelsea Gohd at cgohd@space.com or follow her on Twitter @chelsea_gohd. Follow us on Twitter @Spacedotcom and on Facebook.

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World

Tsunami scars linger a decade later in Japan

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AP PHOTOS: Tsunami scars linger a decade later in Japan

By FOSTER KLUG

March 8, 2021 GMT

TOKYO (AP) — The images still hold the power to shock.

Dazed survivors walk beneath huge sea tankers deposited amid an expanse of rubble and twisted iron that was once a busy downtown, the ships toppled onto their sides like children’s toys. Grieving survivors pick through the flattened debris where their homes used to be. Deserted farms stand in the shadow of the Fukushima nuclear plant, where a catastrophic meltdown still reverberates.

These arresting images were captured by The Associated Press in 2011 after a massive wall of water leveled part of Japan’s northeastern coast, washing away cars, homes, office buildings and thousands of people.

Ten years later, AP journalists have returned to document the communities that were ripped apart by what’s simply referred to here as the Great East Japan Earthquake. The urge to rebuild in a land that has been wracked by millennia of disaster — volcanic eruptions, tsunamis, earthquakes, war and famine — is powerful, and there are areas where there’s little or no trace of the devastation of 2011.

But this triple disaster in the Tohoku region of Japan — earthquake, tsunami and nuclear meltdown — has been unlike any Japan has faced before, and the challenges of returning to what was normal a decade ago have been immense. Half a million were forced from their homes; tens of thousands have not returned, emptying towns that were already struggling to keep their young people from leaving for Tokyo and the other megacities. Radiation fears linger. Government incompetence, petty squabbling and bureaucratic wrangling have delayed building efforts.

Despite the setbacks and uneven progress, the Tohoku of 2021 is a testament to a collective force of will — national, local and personal. Look closely, though, and you’ll see that even the most breathtaking transformations carry the residue of what happened in 2011, the scars of that deep wound to the region’s psyche.

These AP images, then and now, raise a fundamental question: How do you mark change after great trauma?

In one way, it’s the simplest thing in the world to describe. The removal of tons of rubble here, the absence of toppled tankers there. The repaved roads where there had been cracked and buckled piles of asphalt before. The gleaming new buildings that now rise above what had been cleared dirt patches.

But the starkness of this physical change also carries the idea of something that’s much less clear cut, something about the people who live in these places. Their resilience, their stoicism, their grief and anger and stubborn refusal to bow to forces outside their control, whether natural or bureaucratic.

All of that, and more, is present in these powerful scenes of before and after, then and now.

The pictures tell the story — of great change and the people who made it happen.



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Newly found Fukushima plant contamination may delay cleanup

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TOKYO (AP) — A draft investigation report into the 2011 Fukushima nuclear meltdown, adopted by Japanese nuclear regulators Wednesday, says it has detected dangerously high levels of radioactive contamination at two of the three reactors, adding to concerns about decommissioning challenges.

The interim report said data collected by investigators showed that the sealing plugs sitting atop the No. 2 and 3 reactor containment vessels were as fatally contaminated as nuclear fuel debris that had melted and fell to the bottom of the reactors following the March 2011 tsunami and earthquake.

The experts said the bottom of the sealed plug, a triple-layered concrete disc-shaped lid 12 meters (39 feet) in diameter sitting atop the primary containment vessel, is coated with high levels of radioactive Cesium 137.

The No. 1 reactor lid was less contaminated, presumably because the plug was slightly knocked out of place and disfigured due to the impact of the hydrogen explosion, the report said.

The experts measured radiation levels at multiple locations inside the three reactor buildings, and examined how radioactive materials moved and safety equipment functioned during the accident. They also said venting attempt at Unit 2 to prevent reactor damage never worked, and that safety measures and equipment designs still need to be examined.

The lid contamination does not affect the environment as the containment vessels are enclosed inside the reactor buildings. The report did not give further details about if or how the lid contamination would affect the decommissioning progress.

Nuclear Regulation Commission Chairman Toyoshi Fuketa called the findings “extremely serious” and said they would make melted fuel removal “more difficult.” He said figuring out how to remove the lids would be a major challenge.

Removing an estimated 900 tons of melted fuel debris from three reactors is a daunting task expected to take decades, and officials have not been able to describe exactly when or how it may end.

The Fukushima plant was to start removing melted fuel debris from Unit 2, the first of three reactors, later this year ahead of the 10th anniversary of the accident. But in December, plant operator Tokyo Electric Power Co. and the government announced a delay until 2022. They said the development of a robotic arm for the debris removal — a joint project with Britain — has been delayed due to the pandemic.

Under the current plan, a remote-controlled robotic arm will be inserted from the side of the reactor to reach the molten fuel mixed with melted parts and concrete floor of the reactor. Eventually the lids also would have to be removed, but their contamination is a major setback.

The team of experts entered areas inside the three reactors that were previously highly contaminated and inaccessible after radiation levels came down significantly. They’re seeking data and evidence before they get lost in the cleanup.

Massive radiation from the reactors has caused some 160,000 people to evacuate from around the plant. Tens of thousands are still unable to return home.

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Follow Mari Yamaguchi on Twitter at https://www.twitter.com/mariyamaguchi



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