Monitoring Volcano Deformation Based on Synthetic Aperture Radar (SAR) Data

Two main techniques are presented : InSAR (Interferometric SAR), which uses phase differences to create interferograms revealing vertical and horizontal ground displacements, and pixel offset tracking, which analyzes amplitude shifts to measure surface movements—particularly useful for strong deformations or near-field signals that InSAR may not capture accurately.

By combining time series analysis of multiple SAR images, the chapter shows how scientists can track the temporal evolution of ground deformation. These measurements are crucial for interpreting magma storage, migration, and surface transport, and for modeling underground volcanic processes. The chapter also explains how factors like magma source depth, orientation, geometry, and radar acquisition parameters influence the resulting interferogram patterns, supported by synthetic examples.

In addition, the chapter reviews the state of near-real-time volcano monitoring using SAR imagery in observatories worldwide, highlighting recent advancements in automated processing chains, integration with ground-based measurements, and the potential to improve early warning systems and hazard assessment. Practical examples demonstrate how SAR data have helped anticipate volcanic activity, guide evacuations, and monitor magma intrusions in real time.

This work provides valuable guidance for researchers and volcano observatories, combining theoretical principles, practical applications, and recommendations for future monitoring strategies.