Mapping soil moisture and vegetation optical depth as precursors of recent extreme wildfires in Chile

In February 2024, wildfires broke out in Chile’s Valparaíso region, spreading rapidly over the wildland-urban interface into one of the deadliest global fire since 1900. Our research examined the ground conditions that allowed recent Chilean wildfires to take such proportions. Previously, we found that some large fires occurred exclusively under low soil moisture conditions. Building on these findings, we continued to explore the link between burned areas and other precursor variables in the environment. Using publicly available satellite data, we evaluated potential patterns in vegetation optical depth and vegetation water content prior to the occurrence of wildfires. We also expanded our analysis to include data from multiple sensors such as the Moderate Resolution Imaging Spectroradiometer (MODIS), Soil Moisture Active Passive (SMAP), Soil Moisture and Ocean Salinity (SMOS) and Copernicus Sentinel-1 missions. We tested various thresholds across different lead times and showed the predictive skill of satellite observations to capture dynamic fuel conditions more conducive to large fires. These findings provided new insights into the relationship between C- and L-band measurements and extreme wildfire events. Ultimately, our aim is to evaluate how microwave remote sensing information goes beyond traditional drought indices and existing fire prediction models in identifying exacerbated wildfire danger. This global cooperative project is made possible by a graduate global research grant from the University of Virginia’s Center for Global Inquiry and Innovation.