Reassessment of the Holocene eruptive history of Atitlán stratovolcano, Guatemala

Atitlán volcano, one of the youngest and most active stratovolcanoes in the Central American Volcanic Arc, poses a significant threat to the densely populated regions surrounding Lake Atitlán. Despite its eruptive potential and historic activity, the volcano's recent Holocene stratigraphy and eruptive history remain poorly constrained. This study presents a comprehensive reassessment of Atitlán stratovolcano’s eruptive activity through detailed stratigraphic, petrological, and geochemical analysis carried out on 17 new sections across all flanks of the volcano. Field observations, supported by radiocarbon dating, geochemistry, grain-size, componentry, and petrography, allowed us to identify 10 volcanic units spanning from ∼1421 BC to 1856 AD. These eruptive successions reveal a recurring pattern of multi-phase activity comprising fallout, pyroclastic density currents (PDCs), and lava flows. Petrographic and geochemical analyses confirm that the volcano’s products display basaltic-andesite compositions (53.03-56.73 SiO 2 wt%) within the calc-alkaline series, showing conspicuous mineralogical variability across eruptive phases. Grain-size and componentry analyses highlight the alternation between explosive and effusive dynamics, and the widespread distribution of deposits across all flanks underscores the volcano’s high hazard potential. Volume estimates for the youngest fallout unit (∼0.3 km 3 ) suggest a VEI 3–4 event, consistent with strombolian to sub-Plinian eruptive styles, reaffirming that moderate-magnitude eruptions at Atitlán can produce regionally significant impacts. This work updates the geological map of Atitlán, establishes a robust stratigraphic framework for hazard assessment, and provides new insights into the volcano’s eruptive behavior. These findings hold important implications for volcanic risk management at Atitlán and contribute to the broader understanding of stratovolcano evolution and hazards in similar volcanic systems worldwide. • New stratigraphic framework for Atitlán volcano based on detailed fieldwork and multi-method analysis. • Identification and correlation of 11 eruptive units, including revised relationships between PDCs, fall deposits, and lava flows. • Recognition of three eruptive phases supported by sedimentology, radiocarbon dating, and historical constraints. • Clear distinction between facies, facies associations, and eruptive units, improving previous interpretations. • Updated eruptive history integrating new mapping, and petrographic observations