the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Dynamical changes of seismic properties prior to, during, and after 2014–2015 Holuhraun Eruption, Iceland
Abstract. In volcanic eruption monitoring, it is urgent to promptly detect changes in the volcanic system during the crisis period. Ideally continuous, temporally high-resolution, multidisciplinary data is available for this. However, some volcanoes are only being monitored using a single discipline or a single seismic station. In this case, it makes sense to harvest information from the available limited data set with several different techniques. Changes in the seismic complexity could reveal the dynamic changes due to magma propagation. We tested the performance of Permutation Entropy (PE) and Phase Permutation Entropy (PPE), which are fast and robust quantification of time series complexity, to monitor the change in the eruption process of 2014–2015 Holuhraun in Iceland. We additionally calculated the instantaneous frequency (IF), which is commonly used to monitor the frequency changes in a non-stationary signal. We observed distinct changes in the temporal variation of 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. Finally, we also assessed the influence of the atmospheric noise to be considered in eruption monitoring.
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RC1: 'Comment on egusphere-2024-1445', Anonymous Referee #1, 24 Jun 2024
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This manuscript contains a very careful analysis of dynamical changes of continuous seismic waveforms recorded during the diking episode
and subsequent eruption of Bardarbunga volcano in 2014-2015. The analysis focuses on the use of Permutation Entropy and other useful
metrics that can be applied even if only one station is available which is a common state of affairs in under-monitored volcanoes. The
most interesting results of this work in my opinion are first, the good correlation of PE with discharge rate, and second, the great
sensitivity that PE exhibits in detecting minute changes in the seismic wavefield due to temperature variations. I think that the
manuscript is a good contribution to the field of volcano monitoring, it is clearly written, and it falls within the scope of the
journal. I therefore recommend publication after the comments listed below are taken into account by the authors.1. The part of the manuscript on clustering of the estimated parameters is the weakest since it is subjective and it does not take
into account clustering of other combinations of these parameters. Machine learning algorithms are widely used and software packages
that implement them are readily available, hence I don't understand why the authors have not attempted to perform an objective
analysis of clustering. If such algorithms are applied, then it will be possible to examine clustering beyond the binary (i.e two
parameters at a time) way presented in the manuscript, but rather consider clustering in a higher-dimensional space (e.g., PE, PPE,
IF, discharge rate etc).2. At the end of the conclusions section the authors state that "...our study shows that it is still challenging to determine the
eruption onset after the start of the pre-eruptive seismcity..."; I think that this statement may be accurate for the Holuhraun
diking-eruption case but not for other studied cases that utilized PE such as Gjalp or Shinmoedake cited by the authors. The main
difference between Holuhraun and these past cases is the intense volcanotectonic seismicity prior to eruption due to the lateral
propagation of the dike. The last part of the conclusions should be rephrased so that the reader becomes aware of this crucial
difference and this methodology may be able to pinpoint the eruption onset when seismicity levels are lower.3. In the supporting information Figures S3, and S5-S12 are plotted in a way that is difficult for the reader to easily follow the
description of the authors in the Discussion section. I would suggest that these Figures are redrafted using different color for
different lines by using a double y-axis, in the same way the authors plotted Figure 5 in the main manuscript.Citation: https://doi.org/10.5194/egusphere-2024-1445-RC1
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