This Supplement Document gives more background on the analysis of the high-frequency signals on C-European sub-networks and lightning activity in C-Europe during the study period. We also provide two Ground Motion Visualization (GMV) movies of the normalized vertical ground displacement in Central Europe at DOI: 10.3929/ethz-b-000578373. The first movie shows the space–time evolution of ground motion of normal modes across the seismic networks in C-Europe between 1–6 hrs after the onset of the eruption. The second movie highlights the zero-crossing of normal modes in red in the same time period.
