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LiDAR as a tool to reconstruct lava tube networks and their role in lava flow emplacement

Ed Llewellin1, Tim Orr2

Abstract

Basaltic eruptions can construct complex lava flow fields over days to years. Flow fields comprise an interconnected network of lava channels, tubes, and inflated lava pads that store lava and mediate its transport to the active flow front. Hence, flow-field geometry has a profound influence on the rate of propagation of lava flows and on their hazard potential. Here we investigate the proximal part of a lava flow field produced by the Pu'u'ō'ō eruption of Kīlauea in 2003-4. The flow field is characterized by a series of rootless shields and the lava tubes over which they form. We used hand-held LiDAR, field observations, and an existing airborne LiDAR Digital Elevation Model (DEM), to reconstruct the surface and interior geometry of the drained shields and lava tubes. The drained shields have a large interior void space 10--20 m high and 50--150 m in diameter. Some shields sit over a deeper lava tube which apparently fed their construction. In many cases, interior lobes connect to shallow lava tubes, which feed further shields down-slope. LiDAR reconstructions allow us to characterize the geometry of the transport pathways that developed within the lava flow field, and to relate them the pre-existing topography. The data reveal the complexity of the transport system within the lava flow, and provide the basis for future modelling of lava flow field evolution.