Illuminating Kilauea’s magmatic plumbing system: physics-based modeling of post 2018 simultaneous inflation and deflation

Abstract:

Although among the best instrumented volcanoes in the world, Kīlauea’s summit magma system and its connection to the East Rift Zone (ERZ) remain enigmatic. Quantifying the nature of these reservoirs and their connectivity is essential to understanding the volcano’s dynamics, geochemistry, and petrology. Past studies have identified a ~1.9 km deep Haulema’uma’u (HMM) reservoir and a deeper South Caldera (SC) reservoir at the summit, along with multiple storage areas in the ERZ. Separating deformation due to the HMM and SC reservoirs has been challenging because they most often exhibited signals of the same sign. Following the 2018 lower ERZ eruption, Kīlauea’s summit exhibited unique, simultaneous inflation of the HMM reservoir and deflation of the inferred SC reservoir, indicating potentially concurrent magma transfer between HMM, SC, and the ERZ. We analyze GPS and SBAS DInSAR Sentinel time series to elucidate the nature of the summit magmatic system. We first invert cumulative displacement maps (derived from SBAS) and GPS displacements for the location and geometry of the HMM and SC reservoirs. We find that the SC source has a low aspect ratio of 0.2~ 0.3 (oblate) and a depth of ~3000 m, consistent with previous studies. We then devise a physics-based model that couples pressure-dependent flow between reservoirs with approximate ellipsoidal source models to explain time dependent summit deformations. Preliminary Monte Carlo inversion results favor a hydraulically more conductive shallow conduit connecting HMM and the ERZ, in comparison to a less conductive, deep conduit connecting SC and the ERZ. With simple models and high-quality geodetic data, such an approach should substantially improve our understanding of the connectivity between various inferred magma reservoirs.