Triggering relationships between magmatic and faulting processes in the May 2018 eruptive sequence at Kīlauea volcano, Hawaii

SUMMARY The May 2018 activity at Kīlauea Volcano, Hawaii involved magma transport and dyke intrusion along the East Rift Zone (ERZ) and nucleation of the 4 May 2018 M 6.9 earthquake along the basal décollement of Kīlauea's mobile south flank. Combined Global Positioning Systems (GPS) and Interferometric Synthetic Aperture Radar (InSAR) measurements captured the deformation sequence associated with the dyke intrusion, main shock and eruption episode along the ERZ. The earthquake was encouraged by static stress changes from the preceding magma reservoir inflation, ERZ expansion and fault creep on the décollement downdip of the rupture. Slip models derived from the inversion of GPS displacements indicate peak coseismic slip of 2–3 m. Our model analyses, including of the pre-May 2018 deformation, suggest that prior to this event there was no slip on the section of the décollement that ruptured in the earthquake. The observed magma inflation, rapid fault creep on the décollement and coseismic rupture reflect complex cyclic interactions between the magmatic and faulting processes.