First assessment of the Mayobs15 campaign to monitor the activity of the Mayotte volcano
In order to better understand and observe the seismo-volcanic phenomenon that has been affecting Mayotte since May 2018, a new oceanographic campaign has just taken place from October 1st to 26th, 2020, as part of the actions led by the public authorities under the coordination of the interministerial delegation for overseas major risks (DIRMOM).
Publication date: 29/10/2020
Observatories, Press, Research
Related observatories : Volcanological and Seismological Monitoring Network of Mayotte (REVOSIMA)
Related themes : Natural Hazards
The aim of this MAYOBS 15 mission, from the REseau de surveillance VOlcanologique et SIsmologique de MAyotte (REVOSIMA), aboard the Marion Dufresne ship, was to maintain the seabed measuring stations in working order, carry out seawater analyses, and monitor changes in eruptive activity and submarine relief, submarine seismic activity and fluid emissions since the last campaigns in May (MAYOBS 13-1 and MAYOBS 13-2). Additional geological data have also been acquired that will be useful in understanding the current phenomenon.
The MAYOBS 15 campaign used extensive observation resources, including an autonomous underwater vehicle (AUV), to survey an area of 1,500 km2. It identified new lava flows between 0 and 60 metres thick on the seabed to the north-west of the volcano, indicating the persistence of eruptive activity, still underway at the time of the campaign, in the zone where the secondary swarm earthquakes are generated.
Finally, MAYOBS 15 will have dredged samples of volcanic rock from the marine substratum, in the areas where the new lava flows were emitted, as well as in the “Fer à Cheval” volcanic zone, located 10 km to the east of Petite-Terre. Analysis of these samples will enable us to determine the current and past volcanic activity in the area. The team also collected sediment samples by coring in the area near Petite-Terre, to determine the nature of the sediments and the chronology of past geological events.
During these operations, seismic waves simulated by explosive blasting on land during the REFMAORE campaign were also recorded at sea.
In the context of the COVID 19 crisis, the 44 scientists and technicians on board the Marion Dufresne were all subject to very strict health measures and controls, before and during the mission.
> see the press release from the Prefecture of Mayotte
> see the detailed report on MAYOBS 15 preliminary observations
