Decoding Barva volcano: 26,700 years of eruptions and hazard implications Yemerith Alpízar-Segura a,b,* , Guillermo E. Alvarado c , Paulo Hidalgo d , Peter C. Ryan e , Deina Arroyo-Alpízar f , Antonio Costa g a Ph.D. Program in Science, University of Costa Rica, San Jos´e 11501, Costa Rica b Water Resources Engineering, National Technical University, Alajuela 20101, Costa Rica c Centro de Investigaciones en Ciencias Geol´ogicas (CICG), University of Costa Rica, San Jos´e 11501, Costa Rica d Department of Geosciences, Georgia State University, 38 Peachtree Center Avenue, Langdale Hall, Suite 730, Atlanta, GA 30303, USA e Department of Geology, Middlebury College, Middlebury, VT 05753, USA f Escuela Centroamericana de Geología, University of Costa Rica, San Jos´e 11501, Costa Rica g INGV – National Institute of Geophysics and Volcanology, Bologna, Italy A R T I C L E INFO Keywords: Barva volcano Tephrostratigraphy Dormant volcano Holocene eruptions ABSTRACT Barva is an andesitic shield volcano located 23 km north of San Jos´e (the capital of Costa Rica) and is the only eruptive center near the capital that until now, has no record of historical eruptions. Recent mapping around the summit indicates that at least eight explosive events (VEI 0–3) have occurred in the last 13 kyr. In the last 25 kyr, eruption of several summit and flank lava flows, and cones with basaltic andesite to andesitic composition were interspersed with prolonged dormancy periods. The most important and well-known lava field (12.8 km 2 ) erupted from the basaltic andesitic Monte de la Cruz cinder cone about 17 kyr on the South-southwest flank. The explosive deposits confined to the summit area (within a radius of 10 km around the highest cones at 2906 m a.s. l.) range from a lower tephra fall deposit layer dated at ~13,300 yr BP (from Guararí cone) to the most recent strombolian event around ~250 yr BP (ca. 1700 CE) from Ur´as cone. During the Holocene, the volcano has experienced at least one subplinian (≥6 × 10 6 m 3 DRE) and one strombolian eruption (~3 × 10 6 m 3 DRE), with frequent eruptions whose deposits are consistent with the vulcanian style (between ~2 × 10 6 and ~3.1 × 10 6 m 3 DRE) originating from several small cones and craters at the summit. Periods of dormancy vary between ~750 and ~3820 yr, with approximately 325 yr of quiescence since the last small-volume eruption for which there are no written records due the low population density during the middle of the seventeenth century and its normal cloudy conditions. Results of our radiometric and field data analysis indicate that if explosions similar to those that happened in the past 13 kyr occur in the coming centuries, there could be an impact on the towns near the volcano (about 1200 people), mainly due to pyroclastic flows, ashfall and gas dispersion, while at the country level, the main impact would be due to the dispersion and ashfall. Resumen: Barva es un volc´an en escudo andesítico ubicado a 23 km al norte de San Jos´e (la capital de Costa Rica) y es el único centro eruptivo cerca de la capital que, hasta ahora, no tiene registro de erupciones hist´ oricas. El mapeo reciente alrededor de la cumbre indica que al menos ocho eventos explosivos (VEI 0 – 3) han ocurrido en los últimos 13 ka. En los últimos 25 ka, la erupci´ on de varios flujos de lava de cumbre y flanco y conos con composici´ on bas´altica de andesita a andesítica se intercal´ o con períodos prolongados de reposo. El campo de lava m´ as importante y conocido (12,8 km 2 ) entr´ o en erupci´ on a partir del cono de ceniza andesítico bas´ altico del Monte de la Cruz a unos 17 ka en el flanco sur-suroeste. Los dep´ ositos explosivos confinados en el ´ area de la cumbre (dentro de un radio de 10 km alrededor de los conos m´as altos a 2906 m s.n.m.) van desde una capa de dep´ osito de caída de tefra inferior fechada en ~13,300 a˜ nos a.P. (desde el cono de Guararí) hasta el evento estromboliano m´as reciente alrededor de ~250 a˜ nos a.P. (cono de Ur´as). Durante el Holoceno, el volc´an ha experimentado al menos una erupci´ on subpliniana (≥6 × 10 6 m 3 DRE) y una estromboliana (~3 × 10 6 m 3 DRE), con erupciones frecuentes cuyos dep´ ositos son consistentes con el estilo vulcaniano (entre ~2 × 10 6 y ~ 3.1 × 10 6 m 3 DRE) que se originan en varios conos y cr´ateres peque˜ nos en la cumbre. Los períodos de latencia varían entre ~750 y ~3820 a˜ nos, con aproximadamente 325 a˜ nos de inactividad desde la última erupci´ on de peque˜ no * Corresponding author at: Ph.D. Program in Science, University of Costa Rica, San Jos´e 11501, Costa Rica. E-mail addresses: y.alpizar.s@gmail.com (Y. Alpízar-Segura), galvaradoinduni15@gmail.com (G.E. Alvarado), phidalgo@gsu.edu (P. Hidalgo), pryan@ middlebury.edu (P.C. Ryan), dy.arroyo.a@gmail.com (D. Arroyo-Alpízar), antonio.costa@ingv.it (A. Costa). Contents lists available at ScienceDirect Journal of Volcanology and Geothermal Research journal homepage: www.journals.elsevier.com/journal-of-volcanology-and-geothermal-research https://doi.org/10.1016/j.jvolgeores.2025.108456 Received 14 August 2024; Received in revised form 21 September 2025; Accepted 25 September 2025 Journal of Volcanology and Geothermal Research 468 (2025) 108456 Available online 30 September 2025 0377-0273/© 2025 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.