An exceptional event is taking place under our Indian Ocean feet, worthy of a science fiction film, as a volcano is emerging from the abyss off Mayotte, in a state of almost general indifference.

Illustration : A 3D block of the volcano (MAYOBS mission of REVOSIMA)

Yet this natural event should interest us for several reasons: firstly, it is nothing less than the emergence of a new volcanic island, which like its sisters in the Comorian archipelago, takes its source in the flow of lava that passes under the earth’s crust. Secondly, because this is the first time we have seen the rapid birth of a volcanic island. Finally, and more worryingly, the lava pocket that is currently emptying is located right under the Petite-Terre of Mayotte, which has been subsiding dangerously for several months.
“What is certain is that a major catastrophe could occur in the Petite Terre,” said Pascal Bernard of the Institut Géophysique du Globe in Paris*. The scientist and his colleague Roberto Moretti are predicting a possible collapse of the caldera, the pocket containing the magma that is spreading around the volcano. As this reservoir is located under the island of Petite-Terre in Mayotte, the effects are physically felt there, as earthquakes have been frequent for more than 2 years and the island has already subsided eastwards by 20 centimetres! Not so good news when the waters are expected to rise if the melting of the poles continues at this rate. You don’t need to be a specialist to understand that a rise in the water level associated with the sinking of the island risks making the Mahorais drink the cup…

“A possible collapse of the caldera

To put it simply: the volcanic eruption located about fifty kilometres east of Mayotte originates in the magma pocket located under Petite-Terre and about forty kilometres deep.
To complicate matters, the scientists mentioned above are worried about a probable second pocket located 10 kilometres off the coast of Mayotte and which is “making a piston” of unknown and above all unpredictable proportions.
To sum up, our friends in Mayotte are living with a volcano that is being born at a depth of 3400 metres and 50 kilometres from their coastline, and is already almost a thousand metres high above the ocean floor, which is in danger of collapsing, dragging all or part of the small Earth with it (and a tsunami that would risk swallowing up part of all the coasts bordering our beautiful Mozambique Channel).
To put things in perspective and end on a comical note, one might wonder if this is not why the authorities are dragging their feet on investing in a long runway at Dzaoudzi airport?

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*Les Nouvelles de Mayotte, 25 June 2021 edition.