Application of an Automatic Noise or Signal Removal Algorithm Based on Synchrosqueezed Continuous Wavelet Transform of Passive Surface Wave Imaging: A Case Study in Sichuan, China
Round 1
Reviewer 1 Report
Dear authors,
Thank you presenting your result on using an advanced filtering method to improve ambient noise interferometry and surface wave inversion. I have several comments on your paper:
1. Your paper demonstrates the application of synchrosqueezed continuous wavelet transform on cleaning passive seismic data to improve the inversion results. Therefore, I don't think the Methodology section is quite necessary in your text, or you can just put the methodology to the appendix part, because the theory is well established and it is not quite meaningful to repeat what others have done.
2. To truly demonstrate the benefits of your methodology in improving the final inversion results, I suggest you extract the f-v curve (to the best as you can from Figure 5b), do the inversion, and compare the inversion result with what was shown in Figure 9a and Figure 10. This will demonstrate the benefits of you using the new method for processing passive data. A comparison on Figure 5 and 6/7/8 but not the final inversion results is insufficient, I think.
3. I don't think the Discussion part is essential to your paper, particularly the first and second parts of the Discussion. Maybe a short mention should be sufficient.
Good luck.
Author Response
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Reviewer 2 Report
The goal of this paper is to apply the algorithm proposed by by Mousavi et al. [25] and to validate it to a 1-hour passive seismic dataset acquired in Sichuan, China. The article fit to the journal topic, anyway, in its present form it is difficult to follow by a reader who did not read before the article [25] and is not familiar with this algorithm. In order to improve the quality of the article, Section 1 Introduction and Section 2 Methods have to be rethough (redisigned).
The introduction must present more clear the goal and the originality of the undertaken study. In the Conclusions Section the authors say „In this paper, we applied the noise or signal removal algorithm based on SS-CWT proposed by Mousavi et al. [25] to a 1-hour passive seismic dataset acquired in Sichuan, China, and verified the effectiveness of this method in enhancing passive surface waves.” This is the main achievement of the paper and should be presented at the beginning, in the Introduction section.
In the Introduction an amalgam of ideas is presented, but the reader can not built a complete and clear image of what SI supposes.
In Section 2, the authors picked some equations and ideas from [25], but they are not enough to clarify the algorithm from [25], used in this article. More, there are some shortcomings, e.g.:
- “Equation (2) defines the HOS criterion for distinguishing the Gaussian distribution from the non-Gaussian distribution:” Explain more detailed the HOS criterion
- In equation (3) define delta omega
- equation (4) is not clear
- Define all terms in equation (6) (point to equation (9)). Equation (9) should be written after eq. (6), wher C_Csi appears for the first time.
In Section 4.
In 4.1 „we used the noise separation algorithm”. Please give a bibliographic reference for this algorithm
„We use phase-shift measurement for dispersion analysis, and then used the genetic algorithm [28] to invert the underground shear wave velocity structure.” – a more detailed presentationof the genetic algorithm is required.
„Finally, the shear wave velocity structure profile in this area was obtained by Kriging interpolation”. Give a reference for Kriging interpolation.
To be relevant, Section 5 must provide more details for the statements made.
Author Response
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Reviewer 3 Report
figure 1: scale missing. Could it be pointed out where the roads, villages, rivers and mining activity are located in relation to the passive seismic survey line?
figure 2: vertical axis units are missing
Figure 3: ditto
the discussion should be deepened further. For example, ideas about combining this method with other processing methods to process passive seismic data. What methods? the authors could list a few and comment.
One could also comment on the differences in the environment or conditions of collection of these data with respect to Mongolia, which possibly avoided having similar results.
The conclusions are actually a continuation of the discussion. I don't see direct conclusions. Given the results obtained, it is better to carry the concluding paragraph to a section 5.4 (of the discussion) and eliminate the repeated concepts.
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Reviewer 4 Report
The authors applied synchro squeezed continuous wavelet transform (SS-CWT) method to noise removal from passive seismic data collected in a mining area of Sichuan, China. The authors may add discussion on how the results would be different if they apply different methods other than SS-CWT listed in the introduction to the same data. Can the authors summarize the major factors that contribute to good result by applying the SS-CWT method?
The second sentence of paragraph 2 in the introduction: “However, the diffuse wavefield is impossible to achieve in reality” can be modified to something like: ”However, it is not realistic to obtain the pure diffuse wavefield from observations”.
Author Response
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Round 2
Reviewer 1 Report
Dear authors,
Thank you for addressing my comments. I still have comments on your revised manuscript:
- What are the two figures in Figure 10? What is the difference? Why they have different horizontal axis ranges (1500 vs 1300)? To me they are essentially the same.
- Figure 1: Enlarge fonts and use high-resolution figure.
- Figure 9: inversed should be inverted. Also, you need to capitalize initial and inverted.
- Discussion 5.2: You either include detailed example (a simple plot, or something similar) or your remove it. To me it is not quite useful/meaningful to include such a Discussion without data -- it does not tell anything. You can argue this with the Editor, but this is my opinion.
- Figure 2 caption: I try to rewrite it as: Typical ambient noise data recorded by a geophone in the survey area.
- Methods -> Methodology. Also, you need to briefly summarize the similarity/differences/relation between your presented method and Mousavi's method at the beginning of this section. It is important -- you are not re-inventing the algorithm, you are applying it to a new problem.
- Section 4.4: It is good to have the method described here, but please shorten/briefly summarize the description of the genetic algorithm. Two or three sentences may be sufficient, I think.
Good luck.
Author Response
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Reviewer 2 Report
The authors considered the suggestions indicated in the previous review.
Anyway the description of the genetic algorithm from Section 4.4 (pag.10) should be changed. Even if the authors are not from the computer science field the description is more like an advertising description than a scientific one. In a genetic algorithm we are specifically interested in how a chromosome encodes a solution and how the mutation operation is defined.
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