Years of magma intrusion primed Kīlauea Volcano (Hawai'i) for the 2018 eruption: evidence from olivine diffusion chronometry and monitoring data

The mechanisms that led to the exceptionally large Kīlauea 2018 eruption are still poorly understood and actively debated. External processes such as rainfall events or flank sliding have been proposed to play a triggering role. Here, we present field, geophysical, and petrological observations to show that internal changes within the magmatic plumbing system most likely led to the eruption. Chemical zoning in olivine crystals records the intrusion of primitive magma that is concurrent with deep seismicity and inflation at the volcano’s summit. Magma replenishment and pressurization of the summit reservoirs already started around 2014 and accelerated towards the eruption. Kīlauea volcano was therefore primed to experience a shift in eruptive activity in 2018. This pressure increase associated with reservoir replenishment may have been sufficient to overcome a previously blocked conduit. These findings imply that precursory signs of years of protracted magma intrusion and pressurization of the system may be recognizable in the future, which could lead to improved hazards mitigation.