Volcán de Fuego (Guatemala) monitoring with the Normalized Hotspot Indices (NHI) tool

Abstract. Volcán de Fuego is a stratovolcano located in Guatemala among the most active in the world. In this work, we investigate its eruptive activity from space by means of the Normalized Hotspot Indices (NHI) algorithm. The latter runs operationally under the Google Earth Engine (GEE) platform providing information on active volcanoes at global scale by means of daytime Sentinel 2 MSI (Multispectral Instrument) and Landsat 8/9 OLI/OLI2 (Operational Land Imager) data. In study, we present the results of a time series analysis performed by investigating 40 years of Landsat observations through the NHI algorithm. Results show that during the major periods of thermal activity (e.g., 2000−2003; 2012−2013; 2015−2018) the Volcán de Fuego generated extended lava flows, which were well identified and mapped by satellite. In addition, periods of reduced thermal activity (e.g., 2022−May 2024) marked by NHI were in good agreement with information provided by independent sources. The accurate localization and mapping of high-temperature features, and the characterization of different eruptive phases, demonstrate that the NHI algorithm, through the GEE-App available online (https://sites.google.com/view/nhi-tool/nhi-tool-for-volcanoes), may support scientists also in the monitoring of frequently active volcanoes such as the Volcán de Fuego, providing information about changes of thermal volcanic activity that could precede future and more dangerous eruptions.