The Mayotte island underwent a volcano-tectonic crisis resulting in coordinate variations of more than 20 cm, mainly over the period May 2018 - January 2021. These deformations led IGN to carry out new measurements in autumn 2023, which will lead to the forthcoming publication of RGM23 reference frame in place of RGM04.

IPGP has developed a deformation model which predicts coordinate variations due to the crisis at any point in Mayotte between two specified epochs. To simplify its use, this model has been implemented in the coordinate transformation library proj (free software). A coordinate transformation from ITRF2020 to RGM23 has been derived whatever the epoch of the data to be transformed [a first version provides optimum accuracy over the period 2018 to present]. This model, as well as the transformation derived using this model, are provided for experimental use.

The new RGM04 to RGM23 transformation is also provided for use in proj

• FR(12/03/2025)
• fr_ign_grid_RGM04toRGM23.tif (29/10/2024)
• fr_ign_lonlat_RGM23_deformation_model.tif (28/07/2024)
• fr_ign_RGM23_defmodel.json (18/02/2025 – mise à jour mineure, époque de référence décalée de 12h)

Nouvelle transformation ITRF2020 vers RGM23 / New transformation from ITRF2020 to RGM23

• fr_ign_grid_ITRF2020_RGM23_velA.tif (18/02/2025)
• fr_ign_grid_ITRF2020_RGM23_velB.tif (18/02/2025)
• fr_ign_RGM23_to_ITRF2020.json (18/02/2025)

• Collilieux, X., R. Grandin, I. Pasquier, J. De Oliveira Pinheiro, B. Virly and O. Jamet (2024) How to best account for crustal deformation in Mayotte?, presented at EUREF Symposium 2024, jun 2024
• Grandin R., Collilieux X., Pasquier I. et al., Volcano-tectonic crisis of Mayotte (2018–2022): definition of a semi-kinematic reference frame for geodetic applications, in preparation

Grandin R., Collilieux X., Pasquier I. (2025), Mayotte deformation model, 2018-2022 volcano-tectonic crisis [Data set], doi: 10.57932/41cf41f5-5a0c-47d0-b88d-a774e06e9012