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<p>Volcanic activity disturbs the existing magnetic field, and analysis of the resulting magnetic anomalies provides information about the internal structure and evolution of active systems within edifices. This study focuses on the South-East Rift Zone (SERZ) of Piton de la Fournaise, specifically the eruptive site of September 2022, which offers a unique opportunity to characterise the thermal state, the subsurface structures, and to obtain&#xa0;information about the global fluid dynamics of this highly active area. For this purpose, we performed high-resolution aeromagnetic surveys using an Unmanned Aerial Vehicle (UAV) in November 2022 and May 2024 to investigate the evolution of the eruptive site. At a regional scale, first order 3D modelling of the magnetic anomalies primarily reveals a negative magnetic axis with a N120° orientation. Comparative analysis with 3D Interferometric Synthetic Aperture Radar data modelling shows a significant correlation between this demagnetised axis, the depth, and the volume of magmatic intrusions along the rift-zone. This result suggests the presence of a N120°-trending mechanical weakness intersecting the SERZ that has some control over the internal dynamics of the magmatic and hydrothermal fluids in the area. In addition, we quantify the temporal evolution of the magnetic signals associated with the September 2022 lava flow by means of repeated UAV measurements from May 2024 and estimate a global increase of several hundreds of nanoteslas (between 150 and 900 nT) linked to the magnetisation caused by the lava cooling during this time. We then successfully explore on a more local scale the ability of UAV magnetic prospecting to detect lava tubes using semi-quantitative 2D models. These results demonstrate the potential of UAV magnetic surveys to characterise the spatio-temporal evolution of magnetic signals from Piton de la Fournaise. Such multi-scale analysis of magnetic structures within the edifice indicates the potential of 4D monitoring for obtaining a better understanding of the volcano’s evolution.</p> Graphical Abstract <p></p>

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Insight into magmatic pathways and subsurface structures from repeated UAV magnetic prospecting at Piton de la Fournaise volcano, Réunion Island

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年10月30日

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  • Romain Guillard,
  • Lydie Gailler,
  • Philippe Labazuy,
  • Erwan Thebault,
  • Edouard Régis,
  • Quentin Dumont

摘要

Volcanic activity disturbs the existing magnetic field, and analysis of the resulting magnetic anomalies provides information about the internal structure and evolution of active systems within edifices. This study focuses on the South-East Rift Zone (SERZ) of Piton de la Fournaise, specifically the eruptive site of September 2022, which offers a unique opportunity to characterise the thermal state, the subsurface structures, and to obtain information about the global fluid dynamics of this highly active area. For this purpose, we performed high-resolution aeromagnetic surveys using an Unmanned Aerial Vehicle (UAV) in November 2022 and May 2024 to investigate the evolution of the eruptive site. At a regional scale, first order 3D modelling of the magnetic anomalies primarily reveals a negative magnetic axis with a N120° orientation. Comparative analysis with 3D Interferometric Synthetic Aperture Radar data modelling shows a significant correlation between this demagnetised axis, the depth, and the volume of magmatic intrusions along the rift-zone. This result suggests the presence of a N120°-trending mechanical weakness intersecting the SERZ that has some control over the internal dynamics of the magmatic and hydrothermal fluids in the area. In addition, we quantify the temporal evolution of the magnetic signals associated with the September 2022 lava flow by means of repeated UAV measurements from May 2024 and estimate a global increase of several hundreds of nanoteslas (between 150 and 900 nT) linked to the magnetisation caused by the lava cooling during this time. We then successfully explore on a more local scale the ability of UAV magnetic prospecting to detect lava tubes using semi-quantitative 2D models. These results demonstrate the potential of UAV magnetic surveys to characterise the spatio-temporal evolution of magnetic signals from Piton de la Fournaise. Such multi-scale analysis of magnetic structures within the edifice indicates the potential of 4D monitoring for obtaining a better understanding of the volcano’s evolution.

Graphical Abstract