Historic discovery at sea

Surprise! It’s a Volcano

American Association of Petroleum Geologists (AAPG)
William Sager
William Sager

It’s good that William W. Sager, professor in the Earth and Atmospheric Sciences Department at the University of Houston (formerly professor at Texas A&M University) and lead author of a study that helped discover the largest single volcano on Earth, has a high tolerance for stupid questions.

All the more noteworthy as Sager, an AAPG member who has received the school’s College of Geosciences Award for Distinguished Achievement in Research, has more than 110 refereed articles to his credit.

On the other hand, you find the single largest volcano on earth, people are going to ask how it is possible that everyone else missed something so big.

“Things under the ocean are hard to see,” Sager says, anticipating the question, “so we oceanographers have a great deal of difficulty figuring out what is there sometimes.”

The difficulty, it seems, is counter-intuitive. The bigger things are, the harder they are to locate.

Sager, who has participated in 41 research cruises, explains it this way:

“Imagine wandering across something the size of New Mexico with a flashlight and trying to figure out what it is,” which was the case of the area in question, which came to be known as Tamu Massif (Tamu for Texas A&M; Massif is a geologic term meaning an isolated mountain group, but also is French for – wait for it – massive), located about a thousand miles east of Japan in the Pacific Ocean.

“Indeed, this is an apt analogy because for all of our survey lines, we only crossed a few times,” he continued. “So imagine that you are riding across New Mexico on your bike (that’s about how fast a ship goes) in the dark with a flashlight. That’s about what it is like.”

Helpful Innovations

For those who may have missed the announcement, Sager was the lead author for a team that in early September announced it had found the structure – called by others a “supervolcano” – in the Pacific Ocean.

As reported, the volcano rivals in size the solar system’s largest known volcano, Olympus Mons on Mars.

Other scientists already have said that the discovery will lead to the rewriting of textbooks and rethinking of volcanology.

Sager and his team reportedly first studied Tamu Massif nearly 20 years ago, on a research trip to gather data on an undersea mountain range that contains the structure. They didn’t realize, however, that it was a single structure.

Technological innovations have since entered the scene.

Specifically, Sager says there were two developments that came together during the past four years that made the discovery – and more on that word in a moment – happen now.

“Number one is that we were able to use the R/V Marcus G. Langseth, which is a former industry seismic ship,” he said. “The big sound sources of this ship allowed us to shoot sound waves deep within the volcano and make an image from the returned sound waves.”

He says it was like an x-ray profile of the volcano structure made with sound.

“What these data showed us is that on all of our profiles across Tamu Massif, we saw layering that looks like lava flows running downhill from the summit,” he said. “In other words, there appears to be only one source of the lava flows, and that is at the top of the volcano.”

The second development, he said, was a result of the cores collected by Integrated Ocean Drilling Program Expedition 324 in 2009, which was completed the year before the seismic survey.

“We recovered lots of lava flow samples,” he said. “What was especially interesting is that the lava flows from Tamu Massif were characterized by pulses of flows that are very thick – the maximum we cored is 23 meters, or about 75 feet.”

That was huge.

“That kind of flow occurs in places called ‘flood basalt provinces’ and implies that huge quantities of lava poured out,” he explained. “Such lava flows can run long distances, and this is probably why Tamu Massif has a very low slope – about 1 degree or less. You would have trouble knowing which way is down if you were standing on it.”

Back in Your Own Backyard

But getting back to the “discovery” of this, Sager wants to be careful.

“I have tried to be careful with the word ‘discovered,’” he said.

And this is because, like other scientists, he knew there were these volcanic mountains called oceanic plateaus in the oceans in the region, so it’s not like it was completely foreign.

“Indeed, Shatsky Rise (of which Tamu Massif is part) has been known for nearly a century,” he said. “We knew that Shatsky Rise and others were there. In the past few decades, we knew that they were volcanic.”

But that was when they thought it was a series of volcanoes – not one giant volcano.

“What happened in this study is that we realized it is a single volcano,” he said. “With a volcanic edifice of this size, the more likely thing would have been that it is a complex of volcanoes, similar to the Big Island in Hawaii (which includes Mauna Kea, Mauna Loa, Kilauea, Hualalai and Mahu Kona volcanoes).”

When asked about the enormity of such a find, he says it is almost unimaginable.

“We know that birds are the present-day descendants of dinosaurs,” he said. “Let’s say we didn’t know that there were any bigger than the emu or ostrich. But then we discovered fossils of a T-Rex or a bird of similar size. That’s what we have here.”

To wit, the biggest current volcanoes are on the order of 1/50th of the size of Tamu Massif.”

And then there is the comparison to Mars.

“We compared Tamu Massif with Olympus Mons, which is the biggest known volcano in the solar system,” he said, “so we are not surprised that there are volcanoes of that scale.

“We just didn’t know they were hiding in the backyard.”

Work Continues

Reportedly, there is now no danger of Tamu Massif erupting. But when it did erupt, how powerful was it?

“That’s really unclear,” Sager replied. “Tamu was a basaltic volcano – that’s like Kilauea and Mauna Loa in Hawaii. You can drive up to an eruption and have a look and go have lunch. They are not killer eruptions.”

But that doesn’t mean it won’t ruin your day.

“There was an eruption in Iceland in the 1700s (Laki, or Lakagigar) that had environmental effects in Europe,” Sager said, “but civilization was not wiped out.

“We know the age (approximately) of Tamu Massif, and there is no obvious glitch in the geologic record that you could say is a clear environmental effect of this volcano,” he continued. “Maybe this type of eruption did a little bit of damage, but not enough to wipe out the flora and fauna.

“It seems likely that it would spew lots of gases into the atmosphere and perturb climate, at least a bit,” he said. “But that’s something that scientists still have to work on.”

And speaking of work, when asked what the future holds for him after helping to find something the size, in fact, of New Mexico, something he found by using the right flashlight, Sager, an AAPG member, is somewhat jaded and uncertain.

“Naturally, I will try to get additional data for Shatsky Rise, but this cool result does not translate into new funding.”

How is that possible?

“To get sponsorship from the National Science Foundation, whose funds are stretched thin, I have to convince other scientists that I have a new hypothesis and I can devise a test that will solve the scientific problem that I am proposing – and oh, by the way, it is critical to do it right now.”

Even this project, he says, was a tough sell. And this from a man who has won more than 40 research grants, totaling nearly $4.5 million.

“The seismic survey of which I spoke was turned down four-five times (at one try per year) before my colleague, Jun Korenaga (Yale University), and I finally got it funded.”

And it still wasn’t easy.

“In fact, we didn’t get it funded until the drilling program committed to go out and drill,” he said. “So, I already have submitted a proposal to collect magnetic anomaly data over Tamu Massif. The magnetic lineations formed at the spreading ridges tell us about the evolution of the oceanic crust around Tamu Massif. They were formed about the same time, so the surrounding crust will give us clues about Tamu.

“Some colleagues in Germany are proposing to go to northern Shatsky Rise to dredge some rocks for geochemical studies,” he added. “They are looking at the later evolution of Shatsky Rise.

“It all fits together to help make a clearer picture.”

So, if that all materializes, what then happens next for William Sager, a man who’s been doing this type of work in marine geophysics for 30 years, the former holder of the Jane and R. Ken Williams ’45 Chair in Ocean Drilling Science, Technology and Education while at Texas A&M?

And in quite possibly the greatest and most accurate answer any scientist, any artist has ever given, he says:

“Don’t worry. I’ll keep busy.”

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