Thermal Mapping of Icelandic Geothermal Surface Manifestations with a Drone

Abstract

Rapid advancement and development in drone technologies has made mapping of geothermal surface manifestations doable and routine. In this study a DJI Matrice 210 drone, carrying optical and thermal Flir cameras, successfully maps some 1-2 km2 per day. Deliverables are three orthomosaics of color aerial photo, digital terrain model (DTM) and a map of the surface temperature in °C. By flying no higher than some 200 m above ground, the aerial photo and the DTM have resolution in the few cm range while the thermal map pixel size is about 20 cm. Care has to be put in reformatting the Flir camera radiometric JPG images, in order to correctly process them to orthomosaics in true °C. The thermal image quality is sensitive to air humidity and sunshine. With the three GIS maps at hand, thermal maps collected in four Icelandic locations produce lineaments of geothermal importance, simply be ignoring all temperatures below a certain threshold. With this approach N-S oriented and a few hundred meter long structures in the Svartsengi field, Iceland, are being inferred, together with warm and hot ground locations and suspiciously hot spot in the steam gathering system. The 1973 Eldfell eruption on the Heimaey island in S-Iceland is still emitting heat to surface, inferring the thick lave pile deposited 45 years ago is yet to be fully solidified. The Geysir hot spring area thermal map is confirming previously published N-S orientation of the field main upflow zone, complemented with new warm surface areas, and vivid convection cells in the hot water bowls of Stokkur and Geysir eruptive hot springs. The east flanks of the Snæfellsjökull glaciated strato volcano, are suspected to be heated by a deep seated and currently hidden boiling geothermal reservoir, by cross correlating high elevation vegetation, gaps in the snow cover and gently warm grounds.