TIR Remote Sensing of Volcanic Systems: Recent Advances and Future Perspectives

Thermal InfraRed (TIR; 10-12 μm) remote sensing provides a robust means to quantify Earth’s emitted radiation, enabling the characterisation of surface thermal state and properties. In volcanic environments, these parameters are directly linked to subsurface processes, energy transfer mechanisms, and eruptive dynamics. However, continuous ground-based monitoring is often impractical, especially in remote or inaccessible regions, due both to logistic constraints and hazardous conditions. As a result, satellite-based thermal observations frequently represent the only viable source of systematic, long-term monitoring.

Volcanic heat flux constitutes a fundamental constraint on volcanic processes and eruption dynamics, yet its estimation from space remains incomplete. Current satellite-based retrievals are largely biased toward Mid-InfraRed (MIR; 3.5-4.5 μm) channels, which are well suited for detecting high-temperature eruptive phenomena. When applied to moderate- and low-temperature volcanic processes, however, MIR-based methods underestimate radiative outputs by up to ~90%, limiting their ability to characterise and quantify hydrothermal activity, unrest, eruptive state transitions, and post-eruptive dynamics.

Recent advances in TIR sensor performance, data availability, and processing capabilities have renewed interest in the TIR domain, demonstrating that TIR observations are not merely complementary to MIR data but essential for capturing a wider spectrum of volcanologically relevant parameters.

Here, we illustrate the advantages of TIR-based approaches for volcano monitoring and present recent methodological advances in TIR data processing, from the use of a dedicated hotspot detection algorithm (TIRVolcH) to retrieve spatially resolved quantitative information, to the application of the recently proposed TIR-based Volcanic Radiative Power (VRP_TIR) for quantifying energy release from selected targets and assessing their behaviour. We then show that the synergistic integration of TIR and MIR observations enables discrimination among volcanic features and processes, timely detection of eruptive state transitions, and revision of global volcanic radiative budgets by a factor of 2-20.