It was 2018 and the international scientific community was baffled by a strange buzz emanating from the deep sea since May.
On November 11 the seismic waves were detected in places as distant as Kenya and Chile, Canada and Hawaii; the buzzing was more intense and lasted until half an hour.
“This is a very strange and unusual seismic signal,” a New Zealand earthquake survey fan wrote on Twitter.
This is a most odd and unusual seismic signal.
Recorded at Kilima Mbogo, Kenya …#earthquakehttps://t.co/GIHQWSXShd pic.twitter.com/FTSpNVTJ9B— ******* Pax (@matarikipax) November 11, 2018
In total about 7000 tectonic earthquakes and more than 400 long-lasting seismic signals were detected in those months.
At the same time, in May a team of French researchers discovered a huge underwater volcano near Mayotte, a small island between Madagascar and Mozambique.
It was three miles in diameter, and about 800 meters high from the bottom of the sea. “We have never seen anything like that, ” assured the journal Science Nathalie Feuillet of the Geophysics Institute of Paris.
The finding led scientists to connect the events and now a study confirms that the mysterious seismic signals came from the gestation of the underwater mountain.
Simone Cesca, a seismologist at the GFZ German Geosciences Research Center and lead author of the study published in Nature Geoscience, said to The Washington Post on thursday this marks “the first time we really watched the birth of a volcano at the bottom of the sea. “
His team compiled the observations made by numerous geologists in the last 18 months, beginning with earthquakes. In May 2018, an earthquake of 5.9 was recorded in Mayotte, the largest in the French territory of 250,000 inhabitants, with little previous seismic activity and no volcanic eruption in 4,000 years.
Coincidentally one of the investigators had a sister in Mayotte, worried about her safety after the unusual earthquake. When analyzing earthquakes, scientists discovered that they were the effect of something bigger.
New #geosketchup by @jtuttlekeane on magma draining from a subcrustal reservoir and ascending through the crust near Mayotte: https://t.co/noJetRewEM
Read the associated paper here: https://t.co/4MiB0wEHpZ pic.twitter.com/5q5JVVKu9D
— Nature Geoscience (@NatureGeosci) January 6, 2020
“A bag of magma decided that I wanted to erupt”explained Eleonora Rivalta, a physicist who studies earthquakes and volcanoes at the German Geosciences Research Center.
It was one of the deepest magma chambers ever discovered, approximately 16 to 19 miles (25-30 km) deep. “Once you create a channel to the surface, the magma begins to come out and create the volcano,” Rivalta said. “This is the cause of everything.”
The magma chamber began to drain when the lava moved to the bottom of the ocean. As the chamber became increasingly hollow, its roof began to collapse and rise, Rivalta said.
“Every time the rock sinks into the chamber, it creates a resonance,” said Cesca, “and this produces this strange signal that is perceived far away.”
Cesca said that suspects that the young volcano is about to grow, since most of the magma that built it has probably been drained to the surface. But The magma chamber is so deep inside the Earth’s core that “you never know.”
Edited by Ivette Leyva.
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