Lava flow damage assessment using remote sensing and ground surveys: 2018 LERZ lava flows of Kīlauea volcano, Hawai`i

Abstract:

Damage assessments following volcanic eruptions have primarily been conducted for tephra fall, pyroclastic density currents and lahars. Although a number of communities have been devastated by lava flows in recent decades (e.g. Fogo, Cape Verde, 2014-2015; Nyiragongo, DRC, 2002), there are limited descriptions of lava flow impacts. The 2018 Lower East Rift Zone (LERZ) lava flows of Kīlauea volcano, Hawai`i, offered a unique opportunity for a quantitative impact assessment. Lava flows inundated 32.4km<sup>2</sup> of land covering residential properties, infrastructure and farmland. During and after the eruption, USGS scientists and collaborators took over 8,000 photographs, videos and aerial footage, creating the largest visual impacts database available documenting effusive eruption impacts. Drawing on this dataset, pre- and post-event satellite imagery, and 2019 field damage surveys, we developed a ground-based damage survey form and damage state schema for lava flows. We assessed structures using the geolocated imagery and created a dataset of damage for each structure with each entry assigned an associated damage state and data quality index value. Past work has assumed lava flows cause total destruction when in contact with structures. However, in our study area, the Puna District of Hawai`i, 1,937 structures (95%) were destroyed, but 101 structures (5%) were damaged and not destroyed, demonstrating it is an oversimplification to assume binary damage. Of the damaged structures, 46 (46%) did not come into contact with lava. On the lava flow periphery, structures exhibited a range of damage states, dependent on material type and damage mechanism, with damage by fire observed up to ~600 m away from the flow. Related hazards such as tephra fall and volcanic gases also affected buildings. Our study provides insights into damage from effusive eruptions, contributing to the limited evidence base for forecasting future lava flow impacts.