In March 2021, a six-month eruption began in the Geldingadalir valley in Iceland, characterised by effusion episodes and lava fountains. On 8 June 2021, the active crater featured an active lava pond with episodic lava pond fluctuations. To analyse the eruption on this day in June, we used a seismometer from the University of Cambridge to measure the tremor duration, repose time and amplitude on this day in June. In addition, we used high-resolution videos and images captured by UAS from the German Research Centre (GFZ) in Potsdam, which allowed us to create a digital elevation model (DEM) and an orthomosaic to estimate the lava pond level over time and the diameter of the boiling area. The data used in this study, including videos, DEM, orthomosaic, and a marker file of the start and end of the tremor episodes, are publicly available
The Fagradalsfjall eruption from 19 March to 18 September 2021 featured lava fountaining episodes from 2 May to 14 June. These episodes were recorded as tremor pulses on our broadband seismic station NUPH (Nanometrics Trillium Compact 120s) at 5.5 km southeast of the active vent.
We used the seismic data bandpass filtered between 1 and 4 Hz to mark the start and end of 7058 tremor pulses. The catalog hence comprises 14116 markers, that are statistically further evaluated in Eibl et al. (in review). From 2 May to 14 June, several changes in pulse duration and repose time were found and used to subdivide this time interval into 6 periods with characteristic pulse pattern. We find exponentially decreasing pulse durations, coexisting short and long pulses and stable pulse durations superimposed by gradually increasing or suddenly decreasing repose times. We discuss the findings in the context of an evolving shallow-conduit container, the crater geometries, partial collapses from the crater rim and the amount of accumulating outgassed magma in Eibl et al. (in review). This data publications releases the catalog of 14116 tremor pulses /lava fountaining episodes.