­Activity and hazards of the ongoing eruption of Sinabung Volcano, Indonesia, evaluated using UAS-derived datasets

Sinabung Volcano, located in North Sumatra, Indonesia, has been erupting continuously since late 2013. Activity during the past five years has generally been effusive, though activity style has varied considerably and included the emplacement of a 3 km long andesitic lava flow, frequent collapses of an unstable lava dome, and periodic small-to-medium size ash-rich explosions. At present, collapse of previously erupted lava, capable of generating pyroclastic density currents (PDCs), is the greatest hazard at Sinabung.

We applied structure-from-motion photogrammetry to visual and thermal images captured by a small unmanned aerial system (sUAS) in June-July 2018, and data from previous field work, to describe the current state of activity at Sinabung and quantify past activity. We compare multiple digital elevation models (DEMs) spanning the eruption to estimate the volume of deposits from PDCs and the volume of the 2014 lava flow that has collapsed since its emplacement. We utilize UAS-derived high-resolution topography to infer flow dynamics from lava flow surface morphology, and compare these results to direct observations of the lava flow during its emplacement.

We evaluate the stability of the erupted lava using the Scoops 3D slope stability model to assess the risk of continued lava collapse despite a continued decrease in estimated effusion rates. We compare the collapse risk with temperature maps derived from an sUAS-based thermal camera to identify relationships between areas with higher collapse risk and thermal anomalies. We test a hypothesis that the thermal anomalies identify regions where hydrothermal alteration and/or well-established fracture networks are present, which may further decrease the stability of the area. This study highlights the multiple ways data from sUAS can be used to study and monitor active eruptions.