Eerie Purple Skies Over Japan As Powerful Typhoon Bears Down

The skies turned an eerie shade of purple as one of the most powerful typhoons in decades bore down on Japan's capital. 

Japan has sent tens of thousands of troops and rescue workers to save stranded residents and fight floods caused by one of the worst typhoons to hit the country in recent history, which killed 33 people and briefly paralysed Tokyo.

Nineteen people are missing, public broadcaster NHK said, as Typhoon Hagibis left vast swathes of low-lying land in central and eastern Japan inundated and cut power to almost half a million homes.

More than 170 people are injured according to the Australian Associated Press.

More than 4.4 million people were told to evacuate their homes in eastern and north-eastern Japan after it made landfall south of Tokyo on Saturday and moved north.

As the super typhoon touched and the evacuations began, residents posted images on social media of the skies turning vivid shades of pink and purple.

The skies above Japan. Image: @ika-mesugorira/PA Wire

"Beautiful sky in Japan before the typhoon. Looks peaceful but it's actually an indication that the storm is coming #PrayforJapan," one person wrote on Twitter.

In past similar weather events, purple skies have been said to be the result of  "scattering", a phenomenon where molecules and small particles in the atmosphere change the direction in which light rays travel.

Meteorologist Lauren Rautenkranz explained scattering following Hurricane Michael in the US last year.

"As sunlight shines down to Earth, most of the colours of the spectrum are able to reach the surface uninterrupted," she said.

"This light bounces from particle to particle until it eventually reaches your eyes. But the sky doesn't appear violet and blue because of our eyes' limitations."

While blue is normally detected under normal conditions, purple can sometimes become visible during a storm.

Hagibis means "speed" in the Philippine language, Tagalog, and the government has warned it could be the strongest to hit Tokyo since 1958.

READ MORE: One Dead, Millions Told To Evacuate As Japan's Worst Typhoon In 60 Years Makes Landfall

The typhoon made landfall on Japan's main island of Honshu on Saturday evening. A magnitude 5.7 earthquake shook Tokyo shortly after.

It brought record-breaking rainfall in many areas, including the popular resort town of Hakone, which was hit with 939.5 mm of rain over 24 hours.

Authorities lifted rain and flood warnings for the Kanto region before dawn on Sunday, but imposed them on areas further north after Typhoon Hagibis blasted through the capital.

Pedestrians hold onto umbrellas as rain falls amid strong winds in Tokyo. Image: Getty

Attention focused on Fukushima, where Tokyo Electric Power Co overnight reported irregular readings from sensors monitoring water in its Daiichi nuclear plant, which was crippled by the 2011 earthquake and tsunami.

Ten people have been killed in areas including the Chiba, Gunma, Kanagawa and Fukushima prefectures surrounding Tokyo, public broadcaster NHK said on Sunday.

Among them was a man in his 60s who was found in a flooded apartment in Kawasaki, it said.

Sixteen people were also missing early on Sunday, it said.

Damaged houses in Ichihara, Chiba prefecture. Image: Getty Images

The Japan Meteorological Agency issued the highest alert level for 12 prefectures, warning of potential for once in decades rain totals. It lifted the alerts early Sunday.

"Damage from floods and landslides is likely taking place already," an agency official told a news conference carried by NHK.

"It is critical that people take action urgently to protect their lives and the lives of loved ones."

The capital's main airports, Haneda and Narita, stopped flights from landing and connecting trains were suspended, forcing the cancellation of more than a thousand flights.

Train operators suspended bullet train services extensively, while many train and subway lines in Tokyo were also down for most of Saturday.

On Sunday, Hagibis was over the Pacific, off the north-eastern coast of Japan, travelling north-east at 60 km/h, with wind gusts of up to 142 km/h.

Rugby World Cup Chaos

Japan and Scotland's match in Yokohama will go ahead as scheduled. Tournament organisers confirmed the venue is fit to be used for the final Pool A match on Sunday.

Earlier, the typhoon prompted Rugby World Cup officials to cancel Namibia's match with Canada in Kamaishi.

The decision to cancel the Pool B match was made on safety grounds, organisers said in a statement on Sunday, urging fans not to travel to Kamaishi or the venue, which will be closed.

"Ticket holders will be entitled to a full face-value refund," organisers said.

Kamaishi Recovery Memorial Stadium in Kamaishi. Image: AAP

The Pool C match between the USA and Tonga at Hanazono and the Pool D match between Wales and Uruguay at Kumamoto will go ahead as scheduled.

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Hagibis has left millions confined indoors and streets deserted as record rains and fierce winds flood rivers and threaten widespread damage.