The thermal structure, subglacial topography and surface structures of the NE outlet of Eyjabakkajökull, east Iceland

This study presents the detailed surveys of the NE outlet of Eyjabakkajökull glacier, East Iceland, from the combination of low-frequency ground penetrating radar (GPR), unmanned aerial vehicle (UAV) and GNSS measurements. Data analyses reveal the complex subglacial topography with a prominent, up to 45-m-deep longitudinal trough in the central part of the outlet that serves as the main trunk for the fast ice flow during the glacier surges. During the last decade (2010–2018), the studied part of the glacier has thinned by 4.37 m/yr on average and the ice margin has retreated ~750 m. We detect a boundary between scatter-free zone and zone of intense scattering near the ice margin and relate it to the level of piezometric surface. A very well-developed englacial drainage network in the marginal area of Eyjabakkajökull is determined from the mapped moulins and englacial hyperbolae mainly representing englacial channels. The compressional regime near the almost stagnant ice margin is confirmed from the analysis of the surface structures.