Magmatic and gravity-driven deformation dynamics at Popocatépetl inferred from InSAR and GPS data

Quantifying surface deformation provides critical insights into magmatic processes governing volcanic unrest, as well as into the development of slope instabilities on the flanks of a volcanic edifice. However, it remains particularly challenging in semi-open systems where conventional models often fail, and the geodetic satellite observations reflect the overlapping effects of diverse sources or their absence. In this work, we investigate the Popocatépetl volcano surface displacement field, a persistently active andesitic system known for the emplacement of lava domes and explosive behavior with minimal deformation states. We employed Synthetic Aperture Radar Interferometry (InSAR) and Global Navigation Satellite System (GNSS) measurements, integrated with multiparametric observations from 2019 to 2023. During this period, Popocatépetl exhibited variations in eruptive dynamics, including the destruction of lava domes in 2019 and a transition to a higher-intensity eruptive stage between July 2022 and May 2023, with a low-amplitude inflation phase in GPS baselines that correlated with increased seismicity, degassing and thermal anomalies preceding intense volcanic activity in May 2023. To investigate the deformation mechanisms, we processed interferometric pairs from Sentinel-1A and ALOS-2 satellites to generate surface displacement time series and applied Independent Component Analysis (ICA). We find that the surface displacement field reflects the superposition of multiple processes operating across varying spatiotemporal scales: NE-SW persistent surficial flank motion ( ≤ 50 mm/yr), NE crater subsidence (−40 mm/yr), and a potential superficial westward sliding ( ≈ 10 mm/yr), reflecting complex magmatic and gravitational dynamics.