It comprises a single, immense, rounded dome in the shape of a shield, formed of hardened lava from an eruption around 144 million years ago.
It covers around 310,000 square kilometres (119,000 square miles) - the equivalent area of Britain and Ireland combined - and slopes upwards to a height of around 3.5km above the sea floor.
'Tamu Massif is the largest known single, central volcano in the world,' the team reported in the journal Nature Geoscience.
In area, 'it is ... approximately the same as the British Isles or Olympus Mons on Mars, which is considered the largest volcano in the Solar System.'
It adds: 'Although Olympus Mons seems to be a giant because it is more than 20km in height, its volume is only around 25 per cent larger.'
Olympus Mons, in addition, has relatively shallow roots, whereas Tamu Massif delves some 30km into Earth's crust.
Ocean surveyors had until now surmised Tamu Massif to be a vast system of multiple volcanoes, a kind that exists in about a dozen locations around the planet.
|Mar 10||The children of Japan's Fukushima battle an invisible enemy|
|Some of the smallest children in Koriyama, a short drive from the crippled Fukushima nuclear plant, barely know what it's like to play outside -- fear of radiation has kept them in doors for much of their short lives. (Reuters )|
|Mar 10||Japan Airlines 787 makes emergency landing in Honolulu|
|A Japan Airlines- operated Boeing 787 made an emergency landing at Honolulu Airport after oil pressure in its right engine dropped, the Japanese carrier said. (cbsnews.com )|
|Mar 09||Thousands protest in Japan ahead of Fukushima anniversary|
|Banging on drums and waving "Sayonara nukes" signs, thousands of people rallied in a Tokyo park and marched to Parliament on Sunday to demand an end to nuclear power ahead of the third anniversary of the Fukushima disaster. (scmp.com )|
|Mar 09||Astronaut Wakata becomes commander of International Space Station|
|Astronaut Koichi Wakata, 50, became the first Japanese to serve as commander of the International Space Station on Sunday. (Kyodo )|
|Mar 09||Mt Gox faced 150,000 attacks per second: report|
|Bitcoin exchange MtGox faced massive hacker offensives last month, coming under some 150,000 DDoS attacks per second for several days ahead of its spectacular failure, a report said Sunday. (AFP )|
|Mar 08||Japanese girl bitten 100 times in New Zealand dog attack|
|New Zealand doctors said Friday that a 7-year-old Japanese girl was bitten about 100 times during a dog mauling that has horrified many in the South Pacific nation. (USA Today )|
|Mar 08||Fewer than 40 pct of Tokyo residents, commuters prepared for quake|
|Fewer than 40 pct of residents and commuters in Tokyo take specific measures to prepare for a possible huge earthquake beneath the Japanese capital, despite high awareness on disaster prevention, a Metropolitan Police Department survey showed Friday. (Jiji Press )|
|Mar 08||Blizzard pummels northern Japan|
|A blizzard struck northern Japan on Friday with authorities warning of avalanches, high waves, strong winds and traffic disruption. (thehindu.com )|
|Mar 08||Japanese men do near the least housework|
|An international survey shows Japanese men fell into a group doing the least housework. (NHK )|
|Mar 07||Kashiwa murder suspect says he wanted to fly hijacked plane into Skytree|
|The man under arrest for fatally stabbing one man and wounding three others during a 10-minute rampage in Kashiwa, Chiba Prefecture, on Monday night, told police on Thursday that he wanted to hijack a plane at Haneda airport and fly it into Tokyo Skytree to take revenge on society. (Japan Today )|
|Mar 07||Japan's Beethoven apologizes before cameras|
|The man lauded as "Japan's Beethoven," who has admitted he never wrote his compositions, appeared before cameras for the first time since the scandal surfaced - clean-shaven and minus his trademark sunglasses. (abcnews.go.com )|
|Mar 07||Serial underwear thief operated in three prefectures|
|Police in Sano, Tochigi Prefecture, have indicted a man for stealing more than 200 items of women's underwear in three prefectures. (Japan Today )|
|Mar 07||Kashiwa stabbing suspect's identity: 'celeb NEET'|
|The 24-year-old suspect in the murder of a man on a street in Kashiwa, Chiba Prefecture, on Monday is believed to have posted a profile online in which he identified himself as a "celeb NEET," meaning a celebrity without a job, according to local online news site J-Cast News. (Japan Times )|
|Mar 07||Under 20 pct of nonregular male workers in 20s have girlfriends|
|The proportion of single nonregular Japanese male workers in their 20s who have girlfriends stood at 18.7 pct in 2012, against 30.7 pct for regular employees, a government survey revealed Thursday. (Jiji Press )|
|Mar 06||24-year-old man arrested over knife attacks in Kashiwa|
|Police in Kashiwa, Chiba Prefecture, on Wednesday night arrested a 24-year-old unemployed man over four knife attacks within 10 minutes that left one man dead and three others injured on a street. (Japan Today )|