Explosive Activity on K?lauea's Lower East Rift Zone Fueled by a Volatile?Rich, Dacitic Melt

Magmas with matrix glass compositions ranging from basalt to dacite erupted a series of 24 fissures in the first 2 weeks 2018 Lower East Rift Zone (LERZ) eruption K?lauea Volcano. Eruption styles ranged low spattering and fountaining strombolian activity. Major element trajectories glasses melt inclusions hosted by olivine, pyroxene plagioclase are consistent variable amounts fractional crystallization, incompatible elements (e.g., Cl, F, H2O) becoming enriched 4–5 times as MgO contents evolve 6 0.5 wt%. The high viscosity H2O (?2 wt%) dacitic melts erupting at Fissure 17 account for explosive Strombolian behavior exhibited this fissure, contrast observed basaltic basaltic-andesite melts. Saturation pressures calculated inclusion CO2-H2O indicate that magma reservoir(s) supplying these was located ?2–3 km depth, which is agreement depth body intercepted during drilling 2005 (?2.5 km) seismically imaged Vp/Vs anomaly depth). Nb/Y ratios products similar lavas between 1955 1960, indicating were stored underwent crystallization LERZ >60 years before being remobilized dike intrusion 2018. We demonstrate extensive generates viscous volatile-rich potential hazardous eruptions, may be lurking undetected many ocean island volcanoes.