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Volcanic ash erupted at Stromboli before the 2024 paroxysm adds a new piece to the feeding system puzzle

Claudia D\'Oriano 1, Simone Costa1, Patrizia Landi1, Daniele Andronico2, Antonio Cristaldi2

  • Affiliations: 1Istituto Nazionale di Geofisica e Vulcanologia, sezione di Pisa, Pisa, Italy; 2Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, Catania, Italy

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 84

  • Programme No: 3.16.11

  • Theme 3 > Session 16

Abstract

We present a petrological study of a time series sampled at Stromboli volcano between April 9th and August 3rd 2024. In the observed period, a continuous spattering activity started in early May and caused the rapid growth of hornitos at ​​the North-East vent area. On July 3rd-4th, the intensification of spattering led to the partial collapse of the NE portion of the crater terrace, favoring the opening of low-elevation vents that gave rise to lava flows along the Sciara del Fuoco. The effusive activity culminated in the violent paroxysm of 11th July, followed by the interruption of all eruptive phenomena until the end of July. Studied samples include ash and lapilli emitted both during the ordinary Strombolian activity and paroxysm. SEM-EDS-based chemical and textural analyses of groundmass glasses and mineral phases reveal that ash and lapilli have a different petrological signature. Ash emitted before the paroxysm is characterized by complex mingling textures and compositions that are not detected in the lapilli fragments. Associated compositional trends partially diverges from the typical mixing between the two melts that characterized the Stromboli feeding system, tracing an evolution by mingling and crystallization involving a component derived from the crystal mush. Previous studies detected at least < 3% of deep-sourced magma in the ash fraction erupted during the ordinary activity at Stromboli, while in two ash samples collected in May 2024 we found about 15-20% of clasts with these petrological features, suggesting an increasing of the magma supply from depth at least two months before the paroxysm.