Towards reliable X-band InSAR monitoring of complex deformation: Insights from the 2024-2025 Fentale-Dofen Magma Intrusion

Recent advances in satellite remote sensing, particularly high-resolution and high-temporal-frequency SAR systems, provide new opportunities for capturing rapidly evolving deformation. X-band InSAR (Interferometric Synthetic Aperture Radar) data from the COSMO-SkyMed (CSK) and COSMO-SkyMed Second Generation (CSG) constellations offer dense temporal sampling and high spatial resolution, making them particularly valuable for monitoring complex, rapidly evolving deformation signals. However, the short wavelength of X-band data can make phase unwrapping – the step required to convert wrapped interferometric phase into continuous surface displacement – challenging when the signal has a large footprint, large deformation gradients and surface discontinuities.

Here we present an enhanced X-band InSAR monitoring framework applied to the 2024-2025 Fentale-Dofen dyke intrusion in Ethiopia. The dyke measured ~50 km in length and produced complex surface deformation spanning ~10,500 km², with InSAR line-of-sight displacements up to ~3 m over ~60 days. Monitoring dyke intrusion-related deformation is important for understanding magma movement, assessing volcanic hazards, and supporting rapid response during period of unrest. We address limitations of conventional phase unwrapping in areas of complex deformation, including dense fringes caused by dyke-opening and discontinuous deformation within the graben. By integrating pixel-offset tracking with interferometric phase, we develop a reliable offset-supported unwrapping strategy that allows robust recovery of surface displacement associated with both dyke opening and graben subsidence, with consistency evaluated by loop-closure tests. The resulting deformation products provide a consistent basis for InSAR time-series analysis using dense CSK observations, allowing the temporal evolution of intrusion-related deformation to be resolved at high spatial and temporal resolution. Ongoing work extends this framework toward integrated deformation modeling, combining geodetic observations with physics-based representations of dyke-driven magma transport to better constrain subsurface processes.

This study demonstrates how advanced InSAR processing strategies and multi-technique data integration can unlock the full potential of high-resolution X-band SAR data for environmental hazard monitoring. The proposed framework contributes to the development of robust remote sensing tools for deformation analysis, supporting both near-real-time monitoring and post-event assessment of volcanic and other hazards.