Kilauea on the island of Hawaii is one of the best studied volcanoes on Earth with >100 years of geophysics, field and gas monitoring. Two eruptions are ongoing at Kilauea Volcano. One started in 1983 along its east rift zone and the other began in 2008 within the summit caldera. The rift eruption is voluminous (4.5 km3 ) whereas the summit eruption has only periodically spewed debris from its recycling lava lake triggered by rockfalls from its walls. We have sampled and analyzed products from both eruptions since their inceptions. Petrologic and geochemical studies, coupled with field and geophysical observations, yield remarkable insights into magmatic processes both within the crust and the mantle. One key tool for determining magma history is the Mg-rich mineral olivine, the first and typically only mineral to crystalize In Kilauea lavas. Olivine can not only preserve the type of magmatic process (crystallization or magma mixing) but also timescales of when these events occurred. These timescales provide a powerful tool for inferring the duration of magma storage and transport within the crust.
Lava from the long-term rift eruption show remarkable variations in major and trace element concentrations, and Pb, Sr, O and U-series isotope ratios. These variations provide unique insights into the dynamic processes during a single magmatic event. No other eruption anywhere has been studied in comparable detail. The geochemical variations involve the interplay between mantle processes such as melting and source heterogeneity, and crustal processes such as crystallization, assimilation, and magma mixing. In contrast, the summit eruption has produced lavas with a small range in major and trace element composition, which were distinct initially from coeval rift lava but merged in composition with rift lava after a few months. Surprisingly, compositions subsequently diverged. The temporal and spatial variations in rock compositional will be used to interpret the magmatic architecture of Kilauea volcano, which is the archetype oceanic island volcano.