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Abstract:
The use of ocean bottom pressure (OBP) records is crucial to monitor seafloor motion caused by tectonic and magmatic processes. However, accurately monitoring seafloor deformation through time with OBPs is challenging due to instrumental drift and oceanic variations at different timescales. In the context of the Mayotte volcanic crisis in the western Indian Ocean in 2018, three RBR Ambient-Zero-Ambient (A0A) drift-controlled pressure gauges were consecutively deployed (2020-2022) to monitor seafloor vertical deformation. The A0A system estimates instrumental drift by periodically venting ocean pressure to a reference atmospheric pressure.Since no significant vertical ground displacements have been recorded by ground GNSS stations since 2020, this study aims to assess the calibration method of the A0A system, reduce oceanic “noise” in corrected OBP records, and discuss the ability to observe any seafloor deformation offshore Mayotte. Numerical models, including ocean circulation (OGCMs) and barotropic models, were used to understand the influence of the different processes and to reduce the oceanic “noise” in drift-corrected OBP records. Additionally, temperature and salinity data collected by repetitive glider transects were used to validate OGCMs in the region and quantify the contribution of unresolved processes to OBP records.
Our results provide valuable insights into the feasibility of using numerical modeling for improving the accuracy of OBP-based monitoring in the context of the Mayotte volcanic crisis as well as for other seafloor deformation monitoring. It also has important implications for future A0A deployments and in the perspective of the planned MARMOR seafloor cabled observatory.
