Dynamical changes in seismic properties prior to, during, and after the 2014–2015 Holuhraun eruption, Iceland

Abstract. When a volcano is monitored using only a single discipline or a single seismic station, it becomes important to harvest information from the limited data set. Changes in the seismic complexity could reveal a dynamic change due to magma propagation. We evaluated permutation entropy (PE) and phase permutation entropy (PPE) to monitor the 2014–2015 Holuhraun eruption in Iceland. These methods provide fast and robust quantification of time series complexity. We additionally calculated the instantaneous frequency (IF), commonly used to monitor the frequency changes in a non-stationary signal; the root-mean square (RMS); and the root-median square (RMeS) of the seismic amplitude. We observed distinct changes in the temporal variation in PE, PPE, and IF, which are consistent with the changing state from quiescence to magma propagation and then to eruption. During the eruption, PE and PPE fit the lava discharge rate, showing their potential to forecast the duration of the eruption. While one parameter may be more sensitive to one stage, the other may respond better to another stage. Therefore, combining them may provide more reliable information. Cluster analysis of these combined parameters shows clusters consistent with the expert interpretation, confirming the power of these parameters to distinguish different eruption stages.