Near-real time monitoring of the Fagradalsfjall eruption, SW Iceland, based on airborne and satellite stereoimages

– Joaquin BELART – National Land Survey of Iceland & University of Iceland –

Abstract: On the 19th of March 2021, a volcanic eruption started in Fagradallsfjall, SW-Iceland, after a month of increased seismicity and crustal deformation in the Reykjanes peninsula, tens of kilometers away from Reykjavík. As part of the response plan to these events, we organized a series of near-real time monitoring operations using airborne and Pléiades stereoimages. Through the CIEST2 initiative (CNES), Pléiades stereoimages were obtained in emergency mode daily through the first 10 days of the eruption. By comparing Digital Elevation Models (DEMs), we obtained a time series of lava volumes and the effusion rate of the eruption, which was reported to the Icelandic Civil Defense 5-6 hours after the images were acquired.  The derivate products (DEMs, orthoimages, lava thickness maps, lava outlines) have served as a basis for lava flow simulations, hazard assessment and fieldwork logistics. By the 8th of August 2021 (the latest survey), 30 full photogrammetric surveys had been acquired, and the eruption had produced 119±2 millions m3 of lava, with an effusion rate ranging 5-10 m3/s and covering an area of 4.4 km².