Geoflamme, the first scientific campaign on the submarine volcano off Mayotte, has just ended. Scientists have now large amounts of rock and fluid samples as well as amazing high-resolution images of the volcanic edifice.
Hopefully, these new data will provide a better understanding of the formation, evolution and potential environmental impacts of this new underwater volcanic edifice – the youngest and deepest studied to date so close to inhabited areas.
The submarine volcano off Mayotte
In May 2019, a new volcano was discovered 50 km off the East coast of Mayotte by temporal comparison of bathymetric data. It lies on the seafloor at a depth of 3500 m. It is 820 m tall and the estimated erupted volume is over 6 km3.
“The birth of such a volcano is a brutal event for the marine environment. The volume of lava emitted in a few months is estimated at more than 6 km3, or the equivalent of a layer of several tens of meters which would cover the city of Paris,” underlines Emmanuel Rinnert, head of mission.
“Such a young and deep underwater volcano has never been studied. It is an exceptional object and the data we have collected in the field will allow us to better understand it,” he added.
First data show two types of fluid emissions:
- Sea water heated by the lava flow
- Fountains rich in carbon dioxide (CO2) and methane (CH4).
Traces of life such as microorganism biofilms as well as macrofauna such as shrimps are already visible in some of these spots.
Formation and discovery of the underwater volcano off Mayotte
In May 2019, a new 820-meter-high volcano was discovered 50 km off the East coast of Mayotte at a depth of 3500 m.
Actually, thousands of earthquakes are rattling Mayotte since May 2018. Those earthquakes can be grouped in two main areas:
- May 2018 swarm: about 25 km to the East of Petite Terre and 25 to 50 km deep. The largest earthquakes are found in this series, including a Mw5.9 earthquake that occurred on May 15, 2018.
- August 2018 swarm: The main swarm is between 5 and 15 km to the East of Petite Terre.
The discovery of the submarine volcano explains the earthquake swarms that have been occurring since May 10, 2018 and, although this seismic activity is not directly below the new volcano, which is further East, the two swarm regions are linked to the volcano by magma pathways.
In May 2019, an eruption plume containing lots of gas, dust and particles, almost reached the surface of the ocean, resulting in a thick fog. The eruptions then changed in nature, with fairly fluid lavas that caused the base of the volcano to spread.
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