The evolution of a basaltic fissure eruption

Basaltic eruptions produce lava flows that have the potential to destroy local infrastructure and emit toxic gas and particles that may adversely impact public health. Predicting their style and evolution is therefore a key goal in volcanology. This requires an understanding of the multiphase flow processes that operate within the sub-volcanic system. Field observations of both solidified and erupting basaltic fissures at Kīlauea volcano (Hawai‘i, USA) are synthesised with laboratory analogue experiments to determine the evolving organisation of gas-driven flow patterns within basaltic feeder dyke systems, and their effects on eruptions. Our laboratory kit was designed to perform scaled analogue experiments of bubbly flows in a 3.0 x 2.0 x 0.03 m glass-walled slot. This geometry mimics the geometry of dykes that feed most basaltic eruptions, whereas previous experimental studies have usually assumed a cylindrical conduit. The role that localization of fissure segments plays in shaping eruption behaviour is explored by occluding parts of the top of the slot. We also consider the role played by flooding of the vent with lava, focussing on long-lived systems that are reproduced by a conical vent geometry.  We collate the imagery acquired during our analogue experiments with recent monitoring datasets and a detailed field investigation of the spatial organization of vents and drain-back structures on solidified fissures at Kīlauea to improve our understanding of the controls on the eruptive behaviour of basaltic systems. This study will help interpret the underlying flow patterns within feeder dykes from real-time gas and erupted lava flux measurements.