TEMPERATURE AND DYNAMICS OF THE PYROCLASTIC DENSITY CURRENTS FROM THE MARCH 2025 PAROXYSM OF FUEGO VOLCANO, GUATEMALA
Volcán de Fuego in Guatemala is one of the world’s most active volcanoes, with frequent paroxysms that generate pyroclastic density currents (PDCs), hot flows of volcanic ash, blocks, and gas, which descend the volcano’s flanks, representing a dire risk to populations living near the volcano. This was seen during the volcano’s 3 June 2018 eruption in which PDCs inundated populated areas, resulting in an official count of >430 casualties. Eruptions from Fuego are characterized by the generation of long-runout PDCs caused by the collapse of volcanic material which accumulates on the steep slopes of the cone during the months or years between large paroxysmal episodes. This triggering process remains poorly understood, and collapse-generated PDCs often produce volumes far exceeding those expected from eruption size alone, making them a critically overlooked hazard.
Over the past decades Fuego has typically produced eruptive activity multiple times per hour, with multiple larger paroxysms per year. After an unusually long period of quiescence lasting 49 days which began in January of 2025, a new paroxysm took place on March 9th, resulting in PDCs traveling up to 6 km from the volcano. In August of 2025, we sampled the remaining, still-hot deposits of the March 2025 PDCs. In order to assess the volume, dynamics, and impacts to the channel caused by the PDCs, deposits were identified and analyzed with drone flights, satellite imagery, and photogrammetric techniques, and deposits were sampled for study with granulometric and paleomagnetic methods. Paleomagnetic studies revealed maximum temperatures of clasts within the PDC deposits allowing for the analysis of relative contribution of juvenile material and previously erupted material stored on the flanks of the volcano to the overall volume of the PDCs. These results contribute to better understanding of collapse-driven PDCs a frequent and hazardous yet poorly understood process at frequently active volcanoes like Etna, Stromboli, and Arenal.