What Is the Effect of Seismic Swarms on Short-Term Seismic Hazard and Gutenberg-Richter b-Value Temporal Variation? Examples from Central Italy, October–November 2023

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper "The effect of seismic swarms on short-term seismic hazard and Gutenberg-Richter b-value temporal variation: examples from Central Italy, October-November 2023." presents a study on the effect of seismic swarms on short-term seismic hazard and Gutenberg-Richter b-value temporal variation in Central Italy. This work provides valuable insights into the quantification of seismic hazards and the impact of seismic swarms on short-term variations. The key findings indicate that short-term variations of seismic hazards are limited, less than an order of magnitude, and that b-value variations are not significant. Therefore, with the current available models and catalogues, the occurrence of seismic swarms does not significantly affect the short-term seismic hazard. Although this paper deals with an exciting subject, the presentation of this work needs to be improved since the manuscript should introduce important details on, for instance, completeness magnitude and a discussion on b-value and temporal variation. Besides, the authors do not specify the size of the temporal windows used to determine the temporal variation of the b-values. Please see the comments below.

1) The authors stated that they determined the completeness magnitude for the three catalogues considered using the Lilliefors test for the exponentiality of event magnitudes. However, additional details regarding the determination of completeness magnitude need to be introduced.

2) Although the authors employed the weighted likelihood method to estimate the b-value based on all available historical data, they did not specify the size of the temporal windows used to determine the temporal variation of the b-values. Authors should include a brief discussion of this point and the implications of temporal window sizes on their results.

3) If the journal does not require a full stop in the manuscript title, please remove it.

4) A discussion on the b-value and its temporal variation should be conducted in the manuscript's introduction, incorporating relevant references to substantiate the discourse.

5) Please explain that b̂ in equation (2) is the maximum likelihood estimate of the b-value. All variables should be appropriately defined in the text.

6) In the caption of Figure 2, please replace "B-value" with "b-value".

7) Regarding the abbreviations, they must be inserted in parentheses right after the written-out means when defined for the first time. This task should be completed at its first appearance in the main text. I suggest that the authors review the abbreviations entered in the manuscript. For example, consider replacing "MLE" with "maximum likelihood estimation (MLE)" before equation (2). Please consult the Instructions for Authors at https://www.mdpi.com/journal/geosciences/instructions.

 

Comments on the Quality of English Language

Proofreading is needed.

Author Response

See attached file

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Introduction

·        The explanation of mainshock-aftershock sequences (MAs) and seismic swarms (SWs) is clear and detailed. However, it might benefit from a more concise breakdown of complex sentences for better readability.

·        The introduction of Operational Earthquake Forecasting (OEF) systems and their global implementations offers a broad context. However, it might help to specify briefly how these systems operate to better connect them with your investigation.

·        Your intent to study the effect of earthquake swarms on short-term probabilistic seismic rates in Central Italy is clear. Yet, specifying the methodology or approach you'll use for this investigation in brief would strengthen this section.

·        The intention to study the temporal evolution of the b-value parameter of the Gutenberg-Richter distribution due to seismic swarms is clear. Acknowledging the uncertainties related to this parameter's estimation adds balance to your discussion.

The introduction section could benefit from improvement. It lacks a comprehensive literature review and a robust introduction aligned with the current advancements in the field. To enhance this section, it is crucial to delve into recent articles and incorporate relevant citations that align with the state of the art. Below are some of the recent articles that would greatly augment your introduction if thoroughly examined and cited appropriately. Here, I would suggest a couple of very recent publications (in my opinion much more than others)

https://doi.org/10.1016/j.geog.2022.01.003

https://doi.org/10.1007/s40328-023-00430-x

https://doi.org/10.1080/19475705.2022.2029582

https://doi.org/10.1093/gji/ggac028

https://doi.org/10.3390/forecast3030035

Materials and Methods

·        The methodology used to estimate the completeness threshold (ML 1.5) through the Lilliefors test for the Gutenberg-Richter frequency distribution is outlined well. However, a brief explanation of why the chosen method was preferred or its advantages might add depth to this section.

·        The description of OEF-Italy and its functionalities is informative, providing insights into its probabilistic approach and the models used. However, a concise overview of how these models operate or their specific functionalities in relation to your investigation could enhance this part.

·        The detailed explanation of the weighted likelihood method for estimating the b-value parameter is commendable. However, breaking down complex equations or providing a simplified illustration of the method's steps might aid in understanding for readers less familiar with statistical methods.

·        Emphasizing the objectivity and data-driven nature of the b-value estimation method in contrast to subjective choices could reinforce the robustness of your approach.

Figure 1: Add X axis label (Time)

Results and Discussions

·        The historical context of increased OEF rates after past significant seismic events in the three areas adds depth to the analysis. However, reinforcing the comparison between the historical events and the current swarm activity's impact on OEF rates could strengthen the discussion.

·        The analysis of b-value variations over time for the three catalogs is informative. The graphical representation and the comparison with the background values are beneficial for understanding the fluctuations. However, providing a more quantitative analysis or statistical tests to support claims of insignificant deviation from background values might enhance this section.

·        Mentioning that the maximum observed magnitude in the considered time period is smaller than ML 4.5 and discussing the potential bias from aftershock incompleteness due to the completeness threshold (ML 1.5) demonstrates awareness of methodological limitations.

·        While the sections on OEF probabilities and b-value variations are distinct, weaving a more cohesive narrative that connects how changes in seismic activity observed in OEF probabilities relate to or contrast with the b-value variations could improve the discussion's coherence.

Conclusions

·        While you summarize the findings regarding limited impact on OEF probabilities and b-value variations, providing more specific quantitative results (e.g., exact percentages or numerical comparisons) could strengthen the conclusion.

·        Elaborating on why b-value variations might not be significant or how they relate to seismic swarms could enhance comprehension.

·        It might be beneficial to mention potential limitations explicitly, such as data constraints, methodological limitations, or uncertainties in interpreting the findings.

·        The suggestion for alternative methodologies like machine learning is great, but providing a bit more detail on how these methods might overcome the limitations observed could further strengthen the conclusion.

 

Your manuscript offers valuable insights into the limited impact of seismic swarms on OEF probabilities and b-value variations. However, I advise revisiting the references and conducting a more comprehensive literature review to strengthen the context and foundation of your study, ensuring a more robust scholarly framework for your research findings.

Author Response

See attached file

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors addressed all questions.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have adeptly clarified and rectified all the comments that were raised during the review process. Despite this accomplishment, it is imperative for them to ensure strict adherence to the specific citation style mandated by the journal. It is essential that they make the required modifications in accordance with the prescribed guidelines. I strongly recommend that the authors diligently follow the journal's citation style to enhance the overall quality of their publication.