Between May and November of this year, the island was struck by a series of low-grade earthquakes, with the strongest clocking in at a magnitude of 5.8 on May 15, according to National Geographic. But that's not the phenomenon that has scientists up in arms.
Recently, on November 11, a rumble was churning up off the northeast coast of the island that ultimately shook up the entire planet. And no, this wasn't the result of an earthquake, as none were detected at the time. This strange phenomenon started a few minutes before 9:30 a.m. UT.
— Anthony Lomax 🌍🇪🇺 (@ALomaxNet) November 11, 2018
As Nat Geo's Maya Wei-Haas notes, what's even more surprising is that these low-frequency waves, which rang for more than 20 minutes, triggered sensors miles away in Zambia, Ethiopia, Chile, New Zealand, Canada and Hawaii without even being felt by humans.
However, they were spotted by Wellington, New Zealand-based Twitter user @matarikipax, who noticed the oddity on the US Geological Survey's real-time seismogram display. Within moments, the netizen took the matter to social media, bringing to light what they deemed an "odd and unusual seismic signal."
— ******* Pax (@matarikipax) November 11, 2018
And that's when scientists began to collectively furrow their brows as they searched for an explanation for such an incident.
Göran Ekström, a seismologist whose focus is on unusual earthquakes, was also stumped on the matter, telling Nat Geo, "I don't think I've seen anything like it." Ekström definitely wasn't alone.
Jamie Gurney, the founder of UK Earthquake Bulletin, told Business Insider Australia that he had "no idea if a similar global signal of this nature has ever been observed."
The French Geological Survey (BRGM), however, does have some thoughts, suggesting that this is the start of volcanic activity that involves a magmatic movement taking place underneath the Indian Ocean miles away from the island.
The theory might not be too far off, considering that Mayotte is itself the result of volcanism. Another interesting find is that Mayotte has changed its location since the middle of July, moving approximately 60 mm to the east and 30 mm to the south, according to Science Alert, which cited GPS readings.
"It's something quite new in the signals on our stations," Nicolas Taillefer, the head of the seismic and volcanic risk unit at BRGM, told Nat Geo, adding that the area hasn't been mapped out in detail, which poses a setback for investigators trying to dive deeper into the rumblings.
"The location of the swarm is on the edge of the [geological] maps we have… there are a lot of things we don't know."
BRGM is continuing to monitor the area for any changes.