National Geographic News
The Tamu Massif underwater volcano.

A 3-D map of the Tamu Massif formation, which scientists now say is one huge shield volcano

Illustration courtesy IODP

Brian Clark Howard

National Geographic

Published September 5, 2013

A volcano the size of New Mexico or the British Isles has been identified under the Pacific Ocean, about 1,000 miles (1,600 kilometers) east of Japan, making it the biggest volcano on Earth and one of the biggest in the solar system.

Called Tamu Massif, the giant shield volcano had been thought to be a composite of smaller structures, but now scientists say they must rethink long-held beliefs about marine geology.

“This finding goes against what we thought, because we found that it’s one huge volcano,” said William Sager, a geology professor at the University of Houston in Texas. Sager is lead author in a study about the find that was published this week in the peer-reviewed journal Nature Geoscience.

“It is in the same league as Olympus Mons on Mars, which had been considered to be the largest volcano in the solar system,” Sager told National Geographic.

Tamu Massif is a rounded dome that measures about 280 by 400 miles (450 by 650 kilometers), or more than 100,000 square miles. Its top lies about 6,500 feet (about 2,000 meters) below the ocean surface, while the base extends down to about 4 miles (6.4 kilometers) deep. Tamu Massif dwarfs the largest active volcano on Earth, Mauna Loa in Hawaii, which measures about 2,000 square miles (5,200 square kilometers).

Made of basalt, Tamu Massif is the oldest and largest feature of an oceanic plateau called the Shatsky Rise in the northwestern Pacific Ocean. The total area of the rise is similar to Japan or California.

Sager started studying Tamu Massif about 20 years ago. He named it Tamu Massif because Tamu is short for Texas A&M University, where the scientist worked at the time; massif is French for “massive” and is a scientific term for a large mountain.

Scientists had known about the Shatsky Rise since the early 20th century, when it was first mapped, he explained. “We knew it was a big mountain range, but we didn’t know what the structure was like or how it formed,” said Sager.

He added that Tamu Massif is different from classic seamounts, the volcanoes that protrude off the ocean floor around the world by the tens of thousands. Tamu Massif is much larger, with a much more gentle slope than classic seamounts, Sager said.

Near the summit of Tamu Massif, the slope is only around one degree, he said. Down the flank the slope is half a degree, and it’s even less than that near the base. (The average slope of a staircase is 40 degrees, and an easy ski slope is about 10 degrees.) ”If you were standing on the massif, you would have a hard time knowing which way is down,” said Sager.

Finding an Unusual Structure

Scientists had thought the giant Shatsky Rise formed over time as a composite of several volcanoes that grew together, in a process similar to the way the big island of Hawaii was made by the outpourings of five separate volcanoes that were in close proximity.

But when Sager and colleagues looked at seismic data of Tamu Massif, they were surprised at what they found.

“We saw what appear to be lava flows going out from the center of the volcano in all directions, with no obvious large secondary source of volcanism, so that was a surprise,” Sager said.

The team also performed geochemical analysis on core samples taken from the massif. They found that the huge structure appeared to be made out of the same rock, of the same age.

So the scientists concluded that Tamu Massif was created by a single volcano, and probably over a relatively short period of time of a few million years. The volcano went “extinct,” meaning inactive, shortly after it formed, Saged added. That was probably in the Late Jurassic to Early Cretaceous period, about 145 million years ago.

“If what they are saying is correct, that is truly a massive volcano,” said Brian Jicha, a geologist at the University of Wisconsin who has received funding from National Geographic to study the formation of the Aleutian Islands.

“There are a lot of these oceanic plateaus, so if some of them really are just volcanoes, this paper might begin to change the way we think oceanic plateaus are built, and maybe even some of the continental basalt plateaus,” said Jicha, who was not involved in the study.

Sager agrees that more work is needed on other oceanic plateaus. “There could be around a dozen of these things out there,” he said about the possibility of more large shield volcanoes under the sea.

Sager noted that although Tamu Massif currently appears to be the largest single volcano on Earth, there are still larger volcanic complexes, such as the Siberian Traps, which may hold other mysteries. Those features were likely made up of molten rock from different sources, he said, unlike Tamu Massif's formation according to the new theory.

How Did the Volcano Form?

Sager said scientists are still trying to work out the details of how Tamu Massif formed.

He said it seems likely that the spot on the seafloor had the right mix of elements, including a boundary of three tectonic plates, thin crust, and a source of hot magma below that was able to bubble up to the surface. The molten rock poured out, and then built up a wide, gradual rise as it cooled.

Precisely how the magma made it to the surface is an open question. Perhaps a blob of the rock got superheated, and then rose to the surface due to buoyancy. Or, cracks in the overlying crust could have opened, allowing molten rock to spill out.

The next step will be more work to figure out what the source of the magma was, said Sager. He would like to go back and measure the magnetic properties of the rock, using a ship that is equipped with GPS. The data will give him a better idea how the lava spread out, he said.

Jicha added that “if it is indeed really one volcano, and the case is fairly compelling, the amount of magma that had to go through the lithosphere [crust] is off the charts.”

“Not only does [Tamu Massif] give us a new wow in the form of a giant new volcano, but it gives us new insight into a building block of an oceanic plateau,” said Sager.

He’s not sure if the new volcano will help scientists better understand Olympus Mons on Mars, but noted that “we can see the surface of Mars better than we can see the bottom of the ocean.”

Tamu Massif, he said, “has been hiding out for 145 million years because it found a good place to hide.”

Follow Brian Clark Howard on Twitter and Google+.

44 comments
Linda Loughlin
Linda Loughlin

As Sagan said its easier to see the face of Mar than it is under the sea don't believe the Smithsonian when they say it is dead it is a sleeping giant you do not have enough data to make that supposition....

Meena Mehrotra
Meena Mehrotra

The planet continues to amaze us each day with its ever changing phenomenon, do we think we know it all?

PeterthreeDogs Mulshine
PeterthreeDogs Mulshine

This must mean that Earth started out as a smaller planet & over time got bigger & bigger. As volcanic material comes out of cracks /weaknesses in the Earth surface the pressure must be released & the volume expanded.how could it NOT be??

Paul Sojka
Paul Sojka

If it erupted it would be an extinction level event. Lets hope it sleeps for another 150 million years. As far as life goes its a sea mount which means its covered with life.

Roy Acosta
Roy Acosta

japan is near phillipines not affect it is eruption?

Øystein Aasbø
Øystein Aasbø

Hi, nice article.

May I ask what echo sounder system you used to survey the volcano.

Nandan K
Nandan K

how tall is it? how did the lava spread? is there any life there?

Ajim Attar
Ajim Attar

If It exploed imagine how much it has a influence on surrounding areas.

STEPHEN GREENWELL
STEPHEN GREENWELL

In the book The 12th planet, Zecharia Sitchin describes a collision between a moon from Nibiru and earth, that has been backed by earths thin crust in the pacific ocean (thus the ring of fire) and the so called asteroid belt. The more we learn of our planet the more I believe Sitchen was correct. And when Nibiru shows back up, maybe not in my life time, it will prove his research was correct.

Isabella Weeks
Isabella Weeks

Imagine the size of the tsunami if that volcano were to erupt...

Fernando Encluna
Fernando Encluna

so it has been discovered long,long time ago? but only has it been identified as such - - - a volcano? I can't go there to validate, I have to take it by faith, trusting the scientist as such claim, that's a volcano

Betty Glover
Betty Glover

so this is why the news was saying,in case there were a earthquake off of the Alaskan coast,California was to have a major tidal wave.

Erin Viegas
Erin Viegas

So now we know where the Kaiju are.

A. Person
A. Person

It is pretty sad that it took us this long to find this out.

John Ponshock
John Ponshock

National Geographic let's us know that we still have a lot to learn about our planet. Every story is amazing to say the least!

Joey Tariq
Joey Tariq

I Like looking at the different natural hazards and stuff around the world its like really the only thing that gets my attention! ^^ thank you whoever invented national geographic!!!!!!!!! 

Joey Tariq
Joey Tariq

Pretty cool stuff going on around this world! 

Thomas F.
Thomas F.

Interesting discovery, but come on...  OK - It may be one of the largest in the solar system, but still quite small compared to Olympus Mons, on Mars... 

From Mr. Wiki: Olympus Mons (Latin for Mount Olympus) is a large shield volcano on the planet Mars. By one measure, it has a height of nearly 22 km (14 mi). This makes it the tallest mountain on any planet in the Solar System. It stands almost three times as tall as Mount Everest's height above sea level. (...) The total elevation change from the plains of Amazonis Planitia, over 1,000 km (620 mi) to the northwest, to the summit approaches 26 km (16 mi). The summit of the mountain has six nested calderas (collapse craters) forming an irregular depression 60 km (37 mi) × 80 km (50 mi) across[8] and up to 3.2 km (2.0 mi) deep.[9] The volcano's outer edge consists of an escarpment, or cliff, up to 8 km (5.0 mi) tall, a feature unique among the shield volcanoes of Mars.  ((Now, that's impressive!!)

Michael Bauernfeind
Michael Bauernfeind

We need to predict the energy levels in an eruption and use sound waves equal to that energy to contain it…. Or we can use a wormhole to make a 2-coordinate system vortex that contains the molten rock, using sound waves equal to the energy and have a laser cooling system to "freeze"creating a tower that could be used as a launch system for future rockets.Also, due to global warming, EM transmissions, and raising temperatures the "cork" holding the volcano may be slowly unwinding, threatening an eruption only seen in movies, such as "Star Trek".

lorenzo conti
lorenzo conti

How the world didn't notice that,I have no idea.

PeterthreeDogs Mulshine
PeterthreeDogs Mulshine

@Babu Ranganathan The bible is just a fairy tale.It is nothing  to be quoted as a source of intelligence. It  also  taught,that child murder is OK,[despite the commandment NOT TO KILL!!] that if a daughter curses her father[notice it says" father"NOT Mother.,,The father may kill the child.

STEPHEN GREENWELL
STEPHEN GREENWELL

@Babu Ranganathan You must be a KJ only protestant. Date time stamping with our science is only doubted by our ignorance.

We have lost a lot of knowledge over the thousands of years. Time is only measured by humans because we are no longer eternal beings in this body. Time is not relevant to all other existance. You should read my comment above.

Ray Cassidy
Ray Cassidy

@Babu RanganathanYou plonker Rodney Ranganathan!  Not quite sure how people with some form of intelligence can still spout such drivel!

Jackson James
Jackson James

@Babu Ranganathan

Bible Biology?? Wow... dude you have wasted so much of your life trying to prove something that was written in an effort to establish social order.

The bible is riddled with contradictions and I am not going to waste my time listing them. Adhering to the tenants of the bible is a sign of an inability to accept the fact that life has no meaning or purpose and when you die there is nothing. We want to believe there is a god and some of us are so weak that they claim that they wouldn't want to live in a world where god doesn't exist. Well... reality is all about your perspective... Nietzsche said it best when he said the following: 

A casual stroll through the lunatic asylum shows that faith does not prove anything.

You strike me as a pretty intelligent man Babu, you shouldn't waste it on proving that the adult version of Santa Claus really does in fact exist.

If you want a logical construct... God is perfect omnipotent and all knowing and the only thing that exists. God decides one day to create the universe, but paradoxically does so while being perfect. Perfection in every way means that this entity would be with out want or need or desire; therefore, a perfect god would do nothing forever because it would desire nor need to do nothing.

Charles Bundy
Charles Bundy

@Babu Ranganathan 

Yes, quadrillions of gallons of water were floating in the air magically above the earth.  I find this MUCH easier to believe than evolution.

Ronald Garcia
Ronald Garcia

@Thomas F.But it is wider than Olympus Mons.  It is as wide as Britain. Only 25% smaller in total mass than Olympus.

Libro Rumus
Libro Rumus

@Jackson James


Jackson James 


The direct quotation is SO much more appropriate and affords more freedom to the one who listens.


"That faith makes blessed under certain circumstances, that blessedness does not make of a fixed idea a true idea, that faith moves no mountains but puts mountains where there are none: a quick walk through a madhouse enlightens one sufficiently about this."

Paul Sojka
Paul Sojka

Thats great! Are you not entertained? lol.

Brian Howard
Brian Howard expert

@Ronald Garcia Yep. I had actually written more about the comparison between the two mountains, but my editor cut to keep a focus. Olympus Mons is a lot taller than Tamu Massif, but Tamu has a wider base. The reason Tamu could not grow as high is because the crust underneath it is thin and could not support the weight, so it spread out more.

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