Driving Source of Change for Ionosphere before Large Earthquake -Vertical Ground Motion-

Round 1

Reviewer 1 Report

The paper is well written and suggested to be published as it is. 

Author Response

Reviewer 2 Report

Your manuscript contains interesting information about the relationship of variations in vertical soil vibrations with earthquakes in Japan in April 2016. However, the interpretations and conclusions are not adequately supported by the evidence presented. Arguments about the correlation of changes in the power of vertical movements and variations NmF2 are not supported by any model calculations. The NmF2 graphs in Figures 3, 6, 7 and 8 are very small and require pre-processing (filtering) for correct comparison with the data of the seismic measurement network.

Author Response

Reviewer 3 Report

The communication "Driving source to change ionosphere before large earthquake - vertical ground motion" by Chen et al. leaves a strange impression. It s not a review since it is some mosaic presentation. From other side, where is the authors' contribution?

I do not recommend this manuscript for publication in the present form. 

Some minor English revision is necessary.

Author Response

Thanks for the comment. Prior to major earthquakes, small ground motions near faults occur due to energy release. Previous studies have shown that the frequency of these small ground motions tend to increase to lower frequencies when close to the occurrence of earthquake. The main contribution of the authors is to analyze the Hi-net ground motion observation in Japan to confirm the change of the ground motion frequency before earthquakes and the relationship with the plasma density in the ionosphere. The results of this study can be used as a basis for the future earthquake ionospheric precursors. We have added the contribution in the abstract to emphasize it.

Reviewer 4 Report

I am providing my review of the manuscript titled "Driving Source to Change Ionosphere Before Large Earthquake - Vertical Ground Motion," which has been submitted for publication in 

Remote Sensing (ISSN 2072-4292). I had the privilege of evaluating this work as a referee, and I would like to share my assessment and recommendations.

Title: 

The title of the paper effectively conveys the subject matter of the study and its focus on the ionosphere's response to vertical ground motion associated with large earthquakes. It succinctly captures the essence of the research.

Abstract:

The abstract provides a concise summary of the study's objectives, methodology, and key findings. However, I recommend that the authors clarify the reference to "values as saturated as in Figure 4" in the abstract. This statement could benefit from additional context or explanation for readers who are not yet familiar with the contents of Figure 4.

Figures and Tables:

The figures and tables included in the manuscript are informative and contribute significantly to the understanding of the research. In particular, Figure 4 appears to be a pivotal illustration, but as mentioned in the abstract, the reference to the "saturated values" could be made more explicit. To enhance clarity, I suggest that the authors provide a brief caption or description within the figure or figure caption explaining what these saturated values represent and their significance in the context of the study.

Figure 7, which presumably contains variations related to the geomagnetic calm days, should be included with an explanatory note in the manuscript. It would be valuable for readers to understand how these variations relate to the study's findings, as it appears to be an essential component of the research.

Overall, the figures and tables are well-organized and effectively support the narrative of the paper.

Content and Significance:

The study explores the occurrence of small disturbances in vertical ground motion preceding the Kumamoto earthquake in Japan and investigates their potential as earthquake precursors. It employs slant gauge stations distributed throughout Kyushu to measure vertical ground motion and correlates spectral components with changes in NmF2 before the earthquake. The findings are intriguing and underscore the importance of investigating ionospheric disturbances before seismic events.

The paper contributes to the growing body of research on earthquake precursors and enhances our understanding of the physical processes occurring before large earthquakes. It aligns with the journal's focus on geophysics and space science.

Recommendations:

While the manuscript is generally well-structured and written, I have a few recommendations for improvement:

1. Clarify the reference to "saturated values" in Figure 4 in both the abstract and the main text. Explain their significance and relevance to the study's findings.

2. Provide a clear explanation of the content and significance of Figure 7, which appears to be related to geomagnetic calm days. This will help readers understand its importance within the context of the research.

3. Ensure that the manuscript adheres to the journal's formatting and citation style guidelines.

4. Review the manuscript for any typographical or grammatical errors.

In conclusion, I find this paper to be a valuable addition to the field of earthquake precursors and ionospheric research. With the recommended revisions and clarifications, it has the potential to make a meaningful contribution to the scientific community. I recommend that it be accepted after major revisions for publication in 

Remote Sensing (ISSN 2072-4292) after the necessary revisions have been made.

Author Response

Please see the PDF file for the point-by-point response to the reviewer's comments.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

 I think this revised version can be accepted for publication.

Reviewer 3 Report

The MS is improved and revised.

However, the authors must more boldly underline their achievements in Discussion and Conclusions.

Besides this, I recommend to include to the References

Kuverova, V.V. Adamson, S.O., Berlin, A.A., Bychkov, V.L., Dmitriev, A.V., Dyakov, Y.A., Eppelbaum, L.V., Golubkov, G.V., Lushnikov, A.A., Manzhelii, M.I., Morozov, A.N., Nabiev, S.S., Suvorova, A.V., Golubkov, M.G., 2019. Chemical physics of D and E layers of the ionosphere. Advances in Space Research, 63, No. 14, 1876-1886.

Reviewer 4 Report

I am writing to express my decision regarding the manuscript titled "Driving Source to Change Ionosphere Before Large Earthquake - Vertical Ground Motion" submitted to [Journal's Name] for consideration. After a thorough review of the manuscript, I am pleased to accept it for publication in its present form.

The paper presents valuable research on the intriguing topic of ionospheric changes preceding significant earthquakes, specifically focusing on vertical ground motion as a driving source. The methods employed and the results obtained are sound and contribute meaningfully to our understanding of this complex phenomenon.

The study's findings have the potential to advance our knowledge in the field of seismology and ionospheric physics, and I believe it will be of interest to the readership of Remote Sensing. The manuscript adheres to the journal's guidelines and maintains a high standard of scientific rigor.

I would like to commend the authors for their well-structured and comprehensive work, which has undergone rigorous evaluation. I am confident that publishing this manuscript will be a valuable addition to the journal's content.

Thank you for considering my recommendation to accept this manuscript for publication. If you require any further information or clarification, please do not hesitate to contact me.