Assessing lava flow dynamics and rheology using sUAS data
Abstract
The 2018 Lower East Rift Zone eruption of Kīlauea volcano, Hawai'i, devastated communities and infrastructure in East Puna with lava flow inundation and fissure formation. During the eruption, small unoccupied aerial systems (sUAS) equipped with both visible light and thermal cameras were used to monitor the flows and fissures. In particular, sUAS were used to hover above channelized flows and capture centimeter-scale resolution videos of the channel surface. A time-series of repeat observations was made across the eruption zone, including along the 11-km-long 'Fissure 8' channel extending from Leilani Estates to the ocean.
We combine channel hover videos with orthomosaics and digital elevation models of the lava flow to evaluate the spatial and temporal variability of the flow velocity and infer lava rheology. We identify several characteristics of the flow field: velocity magnitude in the channel is not always symmetric about the channel axis; waves are identifiable in the velocity field; flow divergence around obstacles produces bow waves and deceleration in agreement with predictions from analog experiments. We first use a simple analytical solution for flow in a channel to constrain the possible range of channel depth and lava density (a proxy for vesicularity). We then compare the observed velocity field to those calculated by a finite-element numerical model which uses the observed temperature field and channel surface geometry as boundary conditions. We calculate the strain-rate- and temperature-dependence of the lava viscosity and compare to those expected based on lava composition and the microstructure of collected lava samples. The 2018 LERZ eruption provided a wealth of data for comparison with analogue and numerical models and theoretical characterizations of lava rheology. The unique footage collected by sUAS will contribute directly to our understanding of model accuracy and limitations, applicability of analog models to natural systems, and lava rheology representation in models.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.V43J0262L
- Keywords:
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- 8499 General or miscellaneous;
- VOLCANOLOGY