Shallow crystallization of eruptive magma inferred from volcanic ash microtextures: a case study of the 2018 eruption of Shinmoedake volcano, Japan

Abstract The occurrence of groundmass crystals reveals the shallow conduit process magmas, which affects behavior eruptions. Here, we analyzed microtextures ash samples from 2018 eruption Shinmoedake volcano, Japan, to evaluate change magma ascent conditions during sequence. eruptive activity changed venting (Phase 1: March 1–6) lava effusion with continuous ash-laden plumes 2: 6–9) and then shifted Vulcanian explosions 3: 10–April 5). Non-juvenile particles were abundant in Phase 1, whereas juvenile dominant Phases 2 3. Vesicular more than lower microlite crystallinity SiO concentrations vesicular indicate that they sourced ascended rapidly. Abundant nanolites observed black interstitial glass under an optical microscope, few transparent ones. presence can be explained by dehydration silicate melt, as well cooling oxidation between fragmentation quenching. Temporal changes componentry show started erosion pre-existing vent plug 1), simultaneous bubble-bearing outgassed magmas 2), concluded stagnant 3), thereby demonstrating sequence opening extrusion stagnation magma. Therefore, are valuable for monitoring