Seismic sensors first took the event that originated near an island between Madagascar and Africa. Then, the ringing of alarms began to ring as far away as Chile, New Zealand, and Canada.
Hawaii, almost exactly on the other side of the planet, also took the "event".
No one knows what it is.
Meteorite? Submarine volcano? Nuclear test?
"I do not think I've seen anything like that"National Geographic Colombian university seismologist Geran Exstrom says. "That does not mean that, in the end, the reason for them is exotic."
At the center of the mystery is a small island of Mayotte, positioned halfway between Africa and Madagascar. It has been subjected to a swarm of earthquakes since May. Most of them are small, but the largest – on May 8 – were the largest in history history, with a size of 5.8.
But the magic of the earthquake was in decline before the mysterious ring was discovered earlier this month.
Extrm, who specializes in unusual earthquakes, is a lot suggesting that the November 11th event was strange. It was as if the planet was ringing like a bell, maintaining a low-frequency monotone as it spread.
Earthquakes, by their nature, are usually recorded as short sharp "cracks". As tensions in the Earth's crust are suddenly released, the impulses of clearly identified seismic waves emerge outward from where the slip occurs.
The first signal is called the primary wave: high-frequency compression waves that emerge in the clusters.
Then comes the secondary wave: these high-frequency waves tend to "shave" something more.
Only then do surface waves come up: these slow, deep thunderstorms tend to hold back and can circle around the Earth several times.
The November 11th event is known for not detecting any primary or secondary waves.
All registered was a deep, resonant surface wave. And it's not 'wheels' as a surface wave of the earthquake. Instead, it maintained a much cleaner – almost musical – frequency.
The National Geographic Reports of the French Geological Survey suspect that a new volcano might develop off the coast of Mayotte. While the island was created by volcanic activity, it was asleep for more than 4000 years.
The French believe that the strange ringing can be generated by the movement of the magma about 50km from the shore and under deep water. This is supported by GPS sensors detection of Mayotte has moved some 5cm to the southeast in less than five months.
But it is a poorly mapped region. Exactly what is beneath the ocean can only be assumed.
Extrm believes that an unusually pure signal can be caused by a magma that breaks down the inside of the chamber or is forced through the gap in the underground rocks.
But he is not sure.