Monitoring of active volcanoes by means of multi-sensor remote sensing – a case study of the 2014/15 Holuhraun fissure eruption

The Holuhraun fissure eruption in 2014/15 is one of the largest volcanic events in modern Icelandic history. The fissure eruption is a dike intrusion that originated from the Bardarbunga Volcano. In this contribution a combined analysis of multi-sensor remote sensing data monitoring this large volcanic eruption is presented. SO2 and BrO total columns are retrieved from the ultraviolet spectrometer GOME-2 onboard the polar satellites MetOp-A and -B. The sensor measures Earthshine reflectances from nadir-view scans on a daily basis. The atmospheric trace gas retrieval is operationally performed in near-real time (i.e. within 2 hours after measurement) based on the differential optical absorption spectroscopy (DOAS) method in the UV wavelength range. BrO and especially SO2 emissions showed a strong increase when the fissure first erupted in late August 2014. The comparison with Earth Observation satellite imagery of higher spatial resolution showed a strong correlation between the area covered by lava and the amount of SO2 emission. A time series of synthetic aperture radar (SAR) imagery acquired by Sentinel-1 and TerraSAR-X as well as a dataset of Landsat-8 daytime acquisitions was used to monitor the temporal evolution of the lava extent. In addition, very high spatial resolution optical imagery of WorldView-2 and -3 were used for very detailed investigations of the spatio-temporal evolution of the lava extent. Monitoring the hot spot development, datasets of the MODIS fire product have been used and nighttime acquisitions of Landsat-8 as well as imagery of the first satellite of DLR’s FireBIRD mission (TET-1 – Technology Experiment Carrier) were exploited to measure the temperature of the lava over time. The mid-wave infrared channel of TET is ideal for the detection of high temperature events. By additionally interpreting the long-wave infrared channel of TET, it is possible to estimate the kinetic temperature and area of high temperature events simultaneously.