On November 11, between 9:30 and 11:00 UTC, international seismological agencies around the world recorded signals that were unusual and atypical for earthquakes, volcanic activity, falling meteorites or man-made explosions lasting about 30 minutes at very low frequencies.
According to the analysis of seismograms, the signal source was located in the area of Mayotte Island in the Indian Ocean to the north-west of Madagascar. A powerful low-frequency wave swept for an hour and a half from the Mayotte island area to all ends of the world. The unusualness of the signals also lies in the fact that the signal was repeated every 17 seconds at the same frequency.
Earlier, on May 10, the first earthquakes began to occur east of Mayotte Island. On May 15, an earthquake with a magnitude of 5.9 struck, which was the most powerful in the region on record. After this earthquake, aftershocks have been going on for more than six months. The number of aftershocks and their magnitude are gradually decreasing. Nevertheless, in May alone, hundreds of earthquakes occurred.
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The French Geological Survey is closely following developments. According to geologists, the swarm of earthquakes, as well as the unusual signals on November 11, indicate a new center of volcanic activity. Some geologists believe that the earthquake swarm indicates the movement of magma in the earth's crust east of Mayotte.
Since mid-July, GPS stations on the island have tracked its slide more than 6 centimeters east and 3 centimeters south. Using these measurements, Pierre Briolle of the École Normale du Graduate School in Paris estimated the volume of magma to be about 0.3 cubic miles. Pierre Briol believes that magma is breaking through the earth's crust to the surface near the island of Mayotte.
Columbia University seismologist Geran Ekström, who specializes in unusual earthquakes, called the November 11 event similar to a "slow type of earthquake." "Slow earthquake types" are often associated with volcanic activity. On the Nyiragongo volcano in the Democratic Republic of the Congo, similar slow earthquakes and low frequency waves have been associated with the destruction of the magma chamber. Slow quakes were also unusually frequent during the most recent major eruption of Kilauea in Hawaii.
To date, geologists, seismologists and volcanologists have no clear confidence in the reasons for such signals. Most of the current speculation revolves around resonance in the magma chamber caused by some type of subsurface shear or magma chamber collapse. In any case, it can be assumed that an underwater volcano may be born east of Mayotte.