A scientific mission discovered that the unusual seismic activity in the French archipelago was due to an "exceptional geological phenomenon"
For a year, earthquakes have multiplied in the archipelago of Mayotte, whose islands constitute in the Indian Ocean a French department. Thursday, May 16, several ministries announced in a joint statement that a scientific mission had found the person in charge: it is about a very young submarine volcano.
The territory was experiencing unexplained earthquake "In swarm", suffering from more than 1800 earthquakes of magnitude greater than or equal to 3.5, according to the Bureau of Geological and Mining Research (BRGM). The highest ever recorded in Mayotte was recorded at 5.8.
Outstanding geological phenomenon
The volcano whose birth is at the origin of this seismic activity is located at 50 km in the east of the archipelago, by 3,500 m of bottom. Her size "Is assessed at 800 m height with a base of 4 to 5 km in diameter. The plume of volcanic fluids 2 km high does not reach the surface of the water », said the communiqué of the overseas departments, the ecological transition, the interior and the research, which evokes a "Exceptional geological phenomenon".
At a press conference held Thursday at the capital of Mayotte, Mamoudzou, the physicist Nathalie Feuillet, of the Institute of Earth Physics of Paris (IPGB), returned the day before on the mainland after a mission at sea that mobilized about twenty scientists, said that this volcano was recent. "The volcano is thought to have grown since the earthquake swarm started"Nathalie Feuillet said, but we will have to wait for new surveys to know if this growth continues.
"The advantage now is that we know what it is"said the physicist, adding that samples of volcanic rocks had been made. On the other hand, the researcher claimed that Mayotte had dropped 13 cm and moved east about 10 cm. This subsidence, which is "At fairly fast rates"continues, she said. It could be due to "Draining a tank from a deep magma pocket". These announcements come after a scientific mission led by the National Committee for Scientific Research (CNRS), including the BRGM and the IPGP, and an oceanographic campaign carried out by the ship Marion Dufresne, returned to dock Wednesday.
"Reassure the population"
IPGP, French Research Institute for Exploitation of the Sea (Ifremer), University of Reunion, Institute of Earth Physics of Strasbourg (IPGS), National Institute of Geographical Information and Forestry (IGN), the Ecole Normale Supérieure (ENS), the National Center for Space Studies (CNES) and the Hydrographic and Oceanographic Service of the Navy (SHOM) also participated in the mission.
"Scientists are mobilized to process, analyze and interpret the multitude of data acquired in recent months. This operation will require extensive work to assess the risks associated with Mayotte in terms of seismic risk, volcanic risk and tsunami "added the ministries. The prefect of Mayotte, Dominique Sorain, for its part announced that three specialists of the civil security will arrive on the island as of Friday.
Faced with a phenomenon "New to the Indian Ocean area", "The goal of the government is to continue research", he said. "It will require working on this data, it will take a little time", added the prefect, who wishes "A better knowledge of the phenomenon (…) to adapt the answers in terms of security » and "Inform and reassure the population".