New campaign at sea to monitor the evolution of the Mayotte volcano
The MAYOBS15 mission, which will take place on board the Marion Dufresne from October 1 to 26, 2020, aims to maintain instruments and monitor seismo-volcanic activity in the area.
Publication date: 13/10/2020
Observatories, Press, Research
Related observatories : Volcanological and Seismological Monitoring Network of Mayotte (REVOSIMA)
Related themes : Natural Hazards
This mission, planned by the REVOSIMA scientists, will involve more than 30 people on board the boat, in permanent contact with their colleagues on land, during the 16 days of operations in the area.
Work will be carried out to keep the measuring stations on the seabed and in the water column in working order. Thanks to the acquisition of data and underwater sampling, and by comparing them with the data from the last campaign in May, the scientists will be able to assess the evolution of eruptive activity and underwater relief, as well as underwater seismic activity and fluid emissions. The campaign will also provide geological data that will be useful in understanding the current phenomenon.
Which stations record at the seabed?
- Six seabed seismometers (OBS): recording of seabed earthquakes to complement the onshore network.
- Ten additional OBSs: record shots fired on land in association with the REFMAORE mission being carried out at the same time.
- A pressure sensor: very precise measurement of the vertical movements of a point located on the seabed.
- Four hydrophones: recording of acoustic signals from eruptive and seismic sources, as well as those from animal sources (cetaceans).
What measurements and observations will be made?
- Acoustics from the surface: mapping the topography of the seabed and detecting anomalies in the water column.
- Acoustics by autonomous submersible (AUV): high-resolution mapping of the seabed and detection of anomalies in the water column.
- Sediment sounder: location and acoustic imaging of surface sediment layers.
- Bathysonde: in situ measurements to locate geochemical anomalies linked to fluid emissions in the water column.
- Underwater camera (SCAMPI): observation of images from the seabed.
What samples will be taken?
- Rocks (dredges): laboratory analysis of the composition of rocks, including new lava flows, and their gas content.
- Water (bathysonde): on-board and laboratory analysis of gas content, particles and dissolved compounds.
- Surface sediments (corer ~0-10m long): nature of the sediments and sediment deposition conditions.
REVOSIMA:
In response to the seismo-volcanic crisis off Mayotte that began in May 2018, the State entrusted the mission of monitoring this volcanic area to the Réseau de surveillance volcanologique et sismologique de Mayotte (REVOSIMA). The IPGP operates REVOSIMA through the Observatoire Volcanologique du Piton de la Fournaise, with the support of BRGM and its regional office in Mayotte and in close association with Ifremer and CNRS.
As part of REVOSIMA, Ifremer and the French Oceanographic Fleet are responsible for data acquisition and sampling to produce bathymetric maps, petrographic analyses of lava, acoustic and geochemical analyses of the water column, sediment characterisation and observation of the seabed to better understand the phenomenon.
> Find out more on the Mayotte Prefecture website
