Combination of SAR remote sensing and GIS for monitoring subglacial volcanic activity – recent results from Vatnajökull ice cap (Iceland)

This paper presents latest results from the combined use of SAR (Synthetic Aperture Radar) remote sensing and GIS providing detailed insights into recent volcanic activity under Vatnajökull ice cap (Iceland). Glaciers atop active volcanoes pose a constant potential danger to adjacent inhabited regions and infrastructure. Besides the usual volcanic hazards (lava flows, pyroclastic clouds, tephra falls, etc.), the volcano-ice interaction leads to enormous meltwater torrents (icelandic: jökulhlaup), devastating large areas in the surroundings of the affected glacier. The presented monitoring strategy addresses the three crucial questions: When will an eruption occur, where is the eruption site and which area is endangered by the accompanying jökulhlaup. Therefore, sufficient early-warning and hazard zonation for future subglacial volcanic eruptions becomes possible, as demonstrated for the Bardárbunga volcano under the northern parts of Vatnajökull. Seismic activity revealed unrest at the northern flanks of Bardárbunga caldera at the end of September 2006. The exact location of the corresponding active vent and therefore a potentially eruptive area could be detected by continuous ENVISAT-ASAR monitoring. With this knowledge a precise prediction of peri-glacial regions prone to a devastating outburst flood accompanying a possible future eruption is possible. Correspondence to: K. Scharrer ([email protected]) 1 Ice-Volcano interactions in Iceland As the recent formation of the IAVCEI (International Association of Volcanology and Chemistry of the Earth’s Interior) working group of Volcano-Ice interactions demonstrates, the interactions and hazardous effects of subglacial volcanic eruptions are a growing and highly up to date study field. Glaciers atop active volcanoes pose a constant potential danger to adjacent inhabited regions and infrastructure. Besides the usual volcanic hazards (lava flows, pyroclastic clouds, tephra falls, etc.), the volcano-ice interaction leads to enormous meltwater torrents (icelandic: jökulhlaup), devastating large areas in the surroundings of the affected glacier. The subglacial eruption of Gjálp (30 September–13 October 1996) beneath Vatnajökull and the subsequent jökulhlaup (5–7 November 1996) are a good example of the hazardous nature of such an event. During this 48 h cataclysm, a volume of 3.2 km3 of meltwater was discharged at peak rates of about 4×104 m3 s−1, destroying the local infrastructure (roads, bridges, dams, power and telephone lines, etc.) in the adjacent Skeidarársandur (Björnsson, 2002). Only a multidisciplinary approach seems capable of addressing the manifold questions arising with this phenomenon, where we present latest results from the combined utilisation of SAR (Synthetic Aperture Radar) remote sensing and GIS providing detailed insights into recent volcanic activity under Vatnajökull ice cap. Published by Copernicus Publications on behalf of the European Geosciences Union. 718 K. Scharrer et al.: Monitoring subglacial volcanic activity in Iceland