Lava Flow Hazard Prediction And Monitoring With Unmanned Aerial Systems: Case Studies From The 2014-2015 Pāhoa Lava Flow Crisis, Hawai‘i

Abstract

During the 2014–2015 Pāhoa lava flow crisis on the island of Hawai‘i, we used a lowaltitude unmanned aerial system (UAS) to quickly and repeatedly image the active front of a slowly advancing pāhoehoe lava flow dubbed the June 27th flow. This imagery was used to generate a series of 1 m spatial resolution bare-earth digital elevation models (DEMs) and associated paths of steepest descent over the study area. Our updated DEM models show that future flows in this area will likely be deflected by these 2014-2015 flows, possibly threatening communities not directly impacted by the original 2014–2015 lava flow. Over a 4-week period, a series of very high spatial resolution orthomosaics (0.05 m) and digital elevation models (DEM) (0.3 m) provided new insights into the processes that control flow inflation, lava tube growth, flow-front supply rates and subsequent breakouts. Repeated measurements of volume showed a cumulative increase by 1.9 million m3, new supply that was partitioned between inflation (56.5%), surface breakouts (1.4%) and lateral breakouts (42.1%). Detailed measurements of stress cracks and overall growth rates define precursors to locate surgetriggered breakouts. This study provides the first use of UAS to measure the combination of inflation, volume, eruption rate, and morphological changes from high spatial resolution imagery of an evolving flow front, parameters that are all critical to improving our understanding of pāhoehoe behavior in both a hazards context and fundamental flow processes. We demonstrate the value of deploying UAS during a dynamically evolving volcanic crisis and suggest that this technology can fill critical monitoring gaps for Kīlauea and other active volcanoes worldwide.