The tangled tale of Kīlauea’s 2018 eruption as told by geochemical monitoring

Changes in magma chemistry that affect eruptive behavior occur during many volcanic
eruptions, but typical analytical techniques are too slow to contribute to hazard monitoring. We
used rapid energy-dispersive X-ray fluorescence analysis to measure diagnostic elements in lava
samples within a few hours of collection during the 2018 Kīlauea eruption. The geochemical
data provided important information for field crews and civil authorities in advance of changing
hazards during the eruption. The appearance of hotter magma was recognized several days
before the onset of voluminous eruptions of fast-moving flows that destroyed hundreds of
homes. We identified, in near-real time, interactions between older, colder, stored magma –
including the unexpected eruption of andesite – and hotter magma delivered during dike
emplacement.