Birth of an underwater volcano: “This thing was built from zero in 6 months!”… Which is a lot less than 12 years

Guest geological observation by David Middleton

From the American Association for the Advancement of SCIENCE! of America…

Ship spies largest underwater eruption ever
By Roland PeaseMay. 21, 2019 , 1:20 PM

Last week, Marc Chaussidon, director of the Institute of Geophysics in Paris (IPGP), looked at seafloor maps from a recently concluded mission and saw a new mountain. Rising from the Indian Ocean floor between Africa and Madagascar was a giant edifice 800 meters high and 5 kilometers across. In previous maps, there had been nothing. “This thing was built from zero in 6 months!” Chaussidon says.

His team, along with scientists from the French national research agency CNRS and other institutes, had witnessed the birth of a mysterious submarine volcano, the largest such underwater event ever witnessed. “We have never seen anything like this,” says IPGP’s Nathalie Feuillet, leader of an expedition to the site by the research vessel Marion Dufresne, which released its initial results last week.

The quarter-million people living on the French island of Mayotte in the Comoros archipelago knew for months that something was happening. From the middle of last year they felt small earthquakes almost daily, says Laure Fallou, a sociologist with the European-Mediterranean Seismological Centre in Bruyères-le-Châtel, France. People “needed information,” she says. “They were getting very stressed, and were losing sleep.”

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Science! As in “She blinded me with…”

Did I read this correctly?

A sociologist with the European-Mediterranean Seismological Centre…

WTF?

The European-Mediterranean Seismological Centre employs sociologists? They don’t even employ spellcheck.

Ship spies largest underwater eruption ever

Spies? Largest? Ever?

• If the FBI doesn’t “spy”… How can a ship “spy”?
• I seriously doubt that it’s the “largest underwater eruption ever”.

I’m fairly certain that these were a whole lot larger:

Yes… I know those aren’t individual volcanoes… However, all of the Hawaiian islands would have been larger underwater volcanoes before they became islands. Maybe they just mean that it’s the largest underwater volcano that has ever been surreptitiously observed by a ship.

Now that I’ve gotten the easy bits of ridicule out of the way… This is kind of a cool story.

Data from the seismometers, retrieved by the expedition this month, show a tightly clustered region of earthquake activity, ranging from 20 to 50 kilometers deep in Earth’s crust. The team suspects a deep magma chamber fed molten rock to the sea floor and then contracted, driving the cracking and creaking of surrounding crust. GPS measurements on Mayotte also suggest a shrinking magma chamber: They show the island has sunk by 13 centimeters and moved 10 centimeters east in the past year.

The map of the sea floor, made by the ship’s multibeam sonar, indicates that as much as 5 cubic kilometers of magma erupted onto the sea floor. The sonar also detected plumes of bubble-rich water rising from the center and flanks of the volcano. Feuillet says her team didn’t see the shoals of dead fish that fisherman reported, but they did collect water samples from the plumes. The chemistry of the water will give clues about the composition of the magma, the depth from which it came, and the risk of an explosive eruption.

Science! As in “She blinded me with…”

Cassidy says the new volcano is probably too deep to cause a dangerous tsunami onshore. But he is worried by the westward migration of the small earthquakes toward Mayotte, which could potentially trigger a collapse of the submarine flank of Mayotte itself. “This scenario could certainly create a tsunami,” he says.

Feuillet wants to extend her team’s mission by several months to monitor this geological mystery as it develops.

Science! As in “She blinded me with…”