Photogrammétrie: Découvrez la solution Raphal
Photogrammétrie: Découvrez la solution Raphal
Photogrammétrie: Découvrez la solution Raphal
Photogrammétrie: Découvrez la solution Raphal
Photogrammétrie: Découvrez la solution Raphal
- The origins of Mayotte’s seismic swarm : the birth of a new underwater volcano
- The origins of Mayotte’s seismic swarm : the birth of a new underwater volcano
- The origins of Mayotte’s seismic swarm : the birth of a new underwater volcano
- The origins of Mayotte’s seismic swarm : the birth of a new underwater volcano
- The origins of Mayotte’s seismic swarm : the birth of a new underwater volcano
- The origins of Mayotte’s seismic swarm : the birth of a new underwater volcano
- The origins of Mayotte’s seismic swarm : the birth of a new underwater volcano
- The origins of Mayotte’s seismic swarm : the birth of a new underwater volcano
- The origins of Mayotte’s seismic swarm : the birth of a new underwater volcano
- The origins of Mayotte’s seismic swarm : the birth of a new underwater volcano
The origins of Mayotte’s seismic swarm : the birth of a new underwater volcano
Since May 2018, several hundred earthquakes have occurred in Mayotte: sustained seismic activity that seismologists have dubbed an ” earthquake swarm “. As the activity continues, many scientists have mobilised to understand the causes of this phenomenon.
Thanks to the expertise and know-how of TERIA and its partners, the origin has finally been confirmed: an underwater volcano that has just formed 50 km off Mayotte.
The birth of a new volcano
TERIA’s central role in measuring seismic movements
A CNRS scientific mission recently revealed the birth of a new underwater volcano off the coast of Mayotte, an event of exceptional geological significance. This discovery was preceded by warnings from the geodetic coordination project of theInstitut national de l’information géographique et forestière (IGN), with which TERIA, a major player in the collection and analysis of geodetic data, is closely associated.
Thanks to these early observations, geophysicists were able to formulate the hypothesis of a volcanic origin for theswarm of earthquakes shaking the region as early as November 2018.
This new volcano, located 50 kilometres east of Mayotte and at a depth of 3,500 metres, was confirmed during a mission at sea involving around twenty scientists. At the end of the mission, at a press conference in Mamoudzou, Nathalie Feuillet, a physicist at the Institut de Physique du Globe de Paris (IPGP), highlighted the recent formation of this volcano. This observation, made the day before, underlines the importance of the research underway to better understand this phenomenon.
According to a joint press release from the French Ministries for Overseas Territories, Ecological Transition, the Interior and Research, this volcano has been described as an “exceptional geological phenomenon”. It stands out for its impressive size, with an estimated height of 800 metres and a base 4 to 5 kilometres in diameter. A 2-kilometre-high plume of volcanic fluids rises above the volcano, but does not reach the surface of the ocean.
Nathalie Feuillet pointed out that the volcano has continued to grow since the earthquakes began. However, further measurements will be needed to determine whether this growth is continuing. This discovery marks a significant step forward in our understanding of underwater geological processes, and TERIA’s role in monitoring and analysing seismic movements is proving crucial in anticipating and understanding such natural phenomena.
The subsidence and displacement of Mayotte
Since July 2018, Mayotte has experienced a spectacular subsidence of 13 centimetres, accompanied by an eastward displacement of around 10 centimetres. This movement, detected thanks to geodetic observations carried out in October 2018, was measured by the four stations of the Permanent GNSS Network (RGP), two of which belong to the TERIA network and are installed on the island. These stations revealed a monthly displacement of around 1.5 centimetres eastwards and 1.2 centimetres vertically, highlighting a particularly active geological dynamic.
According to Nathalie Feuillet, a researcher at the Institut de Physique du Globe de Paris (IPGP), this subsidence has occurred “at fairly rapid rates” and continues to occur. This phenomenon could be linked to the emptying of a deep magma pocket, causing a subsidence of the Earth’s crust. This hypothesis was put forward following a scientific mission coordinated by the CNRS, with the participation of the Bureau de Recherches Géologiques et Minières (BRGM) and the IPGP, as well as an oceanographic expedition led by the ship Marion Dufresne.
This large-scale scientific project has mobilised many other specialist players. The Institut français de recherche pour l’exploitation de la mer (Ifremer), the Université de La Réunion, the Institut de physique du globe de Strasbourg (IPGS), the Institut national de l’information géographique et forestière (IGN), the École normale supérieure (ENS), the Centre national d’études spatiales (CNES) and the Service hydrographique et océanographique de la marine (SHOM) all contributed to this multidisciplinary study. These collaborations have enabled us to gain a deeper understanding of the geological processes underway in Mayotte, offering new perspectives on volcanic hazards and dynamics in the region.
“Scientists are mobilised to process, analyse and interpret the multitude of data acquired over the last few months”
This operation will require in-depth work to assess the risks for Mayotte in terms of seismic risk, volcanic risk and tsunami risk”, added the ministries.
Faced with a phenomenon that is “new to the Indian Ocean region”,“the government’s objective is to continue the research”, said the Prefect of Mayotte, Dominique Sorain. ” This will require work on the data, which will take some time”, he added, hoping for “a better understanding of the phenomenon (…) to adapt responses in terms of safety” and “to inform and reassure the population”.
Source: AFP, published on Thursday 16 May 2019
