Overview

• Volcanologists have found that increased carbon dioxide from rising magma makes surrounding trees greener, a change measurable by the normalized difference vegetation index (NDVI) in satellite imagery.
• A study of Mount Etna using NASA’s Terra, Landsat 8 and ESA’s Sentinel-2 satellites confirmed that spikes in NDVI closely matched periods of underground magma movement.
• The AVUELO project, led by NASA and the Smithsonian Institution, has deployed spectrometers in tropical forests in Panama and Costa Rica to validate tree greening as a precursor signal.
• Philippine authorities successfully used leaf colour changes detected by satellites to predict the 2018 Rincón de la Vieja eruption and evacuate over 56,000 people.
• Experts caution that satellite-based greening signals must be combined with ground observations, seismic data and deformation measurements for a robust early warning system.