Lava flow forecasting aided by remote sensing during the 2018 Kīlauea lower East Rift Zone eruption

Abstract:

The 2018 Kīlauea lower East Rift Zone eruption on the Island of Hawai‘i effused 0.9–1.5 km³ DRE of lava, destroying infrastructure and homes across >30 km² of the lower Puna District. Over more than three months, lava erupted from numerous fissures and produced rapid and dramatic topographic changes; this had significant implications for tracking lava flow emplacement and assessing the ever-changing areas at risk from lava inundation as the eruption progressed. We integrated probabilistic lava flow modeling with remote sensing of topographic change and flow dynamics to provide timely data and forecasts to emergency managers. Flows were modeled from active vents and channel overflow locations over frequently updated topography using the DOWNFLOW model and similar codes based on steepest-descent paths, while approximating flow thickness and ponding. These tools produced flow routing forecasts, while flow advance forecasts were based on measured advance rates. Up-to-date elevation data was primarily derived through repeated surveys by small unoccupied aircraft systems, airborne syn-eruptive lidar and single-pass interferometry surveys, as well as daily mapping of flow extents and thicknesses using a variety of methods. Fast topographic data processing and rapid modeling allowed for flow forecasts to be issued promptly and with improved accuracy during eruption response. To retrospectively assess these efforts and the importance of updated topography, we compare real-time eruption forecasts with later flow mapping, as well as equivalent simulations over pre-eruptive topography. Our results demonstrate how the evolving lava flow field influenced later flow routing and highlight the value of repeat high-resolution topographic surveys for hazard response. Topographic monitoring of the eruption through time also captured the evolution in lava volume and morphology, providing a critical dataset for understanding lava flow dynamics.