MD 228 / MAYOBS15
Type | Oceanographic cruise |
---|---|
Set | This cruise is part of the set MAYOBS |
Ship | Marion Dufresne |
Ship owner | TAAF |
Dates | 01/10/2020 - 27/10/2020 |
Chief scientist(s) | RINNERT Emmanuel , THINON Isabelle , FEUILLET Nathalie |
GEO-OCEAN - UMR 6538 Univ. Brest, CNRS, Ifremer, Univ. Bretagne Sud Place Nicolas Copernic 29280 Plouzané |
|
DOI | 10.17600/18001745 |
Objective | Monitoring of the seismo / volcanic crisis of Mayotte. As part of the actions carried out by the public authorities, to better understand the seismic-volcanic phenomenon that has affected Mayotte since May 2018, a new cruise is being organized off the island from October 1 to 27, 2020 by the REVOSIMA. The MAYOBS15 cruise aboard the Marion Dufresne aims to establish new underwater maps to monitor seismic-volcanic activity on the seabed. The objective is to acquire data to know whether the volcanic phenomena under -marines detected during the 2019 and May 2020 cruises (lava flows, volcanic fluids) remained active and if new phenomena have occurred since. The seabed will therefore be scanned with an echo sounder which will produce maps of the seabed (so-called bathymetric), to identify possible new volcanic flows and to map the emissions of fluids in the water column. These new cards will allow to monitor the changes observed since May 2020 during MAYOBS13-2. MAYOBS15 includes a section dedicated to the maintenance and recovery of data from seabed seismometers (OBS) which are placed on the seabed up to 3500m of water depth. New stations are also deployed to increase this network of measurements. With a view to seismic refraction measurements, micro-OBS will be deployed offshore in parallel with the installation of geophones on land, during the onshore REFMAORE mission led by the BRGM. MAYOBS15 will make it possible to carry out acoustic surveys from the ship and from an autonomous underwater vehicle and various physicochemical measurements will be carried out by in situ sensors. The parameters monitored concern in particular the evolution of the underwater relief, the physical or chemical anomalies which are linked to the emissions of fluids in the water column. Bottom images will also be recorded by a camera. Finally, MAYOBS15 also aims to collect samples of sediments and rocks on the seabed, but also from the water column. Laboratory analysis of these samples will identify any traces of current or past eruptions. |