Large Scale Thermal Anomalies on Volcanoes as a Precursor to Eruptions

Identifying the observables that warn of volcanic unrest and eruptions is one of the greatest challenges in natural hazard management. A potentially important observable is the release of heat through volcano surfaces, which represents a major energy source at quiescent volcanoes. However, many questions remain open: Is there a direct correlation between surface heat emissions and the subsurface processes that precede volcanic eruptions? To what extent are volcanic eruptions preceded by an enhancement of the surface heat emissions? In this talk, Dr. Girona will show that the last magmatic and phreatic eruptions of five different volcanoes were preceded by subtle but significant long-term (years), large-scale (tens of square kilometres) increases in their radiant heat flux (up to ~1 °C in median radiant temperature). In addition, we will discuss potential mechanisms producing large-scale thermal unrest on volcanoes.