From Hector Mine M7.1 to Ridgecrest M7.1 Earthquake. A Look from a 20-Year Perspective

Round 1

Reviewer 1 Report

This is a very interesting work that clarifies some aspects of the search for earthquake precursors in ionosphere, moving from the concept of “abnormal behavior with respect to the background” to that of “cognitive recognition”. However, there are some important points to be considered before its publication, for which I suggest a major revision.

 

Main points

1. The text is clearly not final: there are at least two cases of repeating some sentences (at pag. 2 and pag. 4), a figure (Fig.2) shows Cyrillic characters and there is some confusion in some figure captions (Fig.6 and Fig.10). Other mistakes are present across the text minimizing the value of the article. Please see the amended pdf text where I suggest some corrections.
2. The concept of “self-similarity” is more complex than used in this paper. I suggest to use the simpler concept of “similarity”. Please see the pdf file.
3. You say that the precursor is a positive nocturne anomaly in TEC. However I also see this feature in the upper-left panel well before (DOY 275) and after (DOY 303-304) the EQ, outside the evidenced rectangle. This same feature appears also in lower-left panel for foF2 after the EQ (DOY 295). Are those false alarms or what?
4. It is strange to me that ACP anomaly (Fig.9) appears after TEC (Fig.8) anomaly. In a bottom-up LAIC process I would expect the opposite. This point should be clearly discussed.
5. In the section “Determination of earthquake forecast parameters”, I think there is not any clear discussion about the uncertainties in the various determinations (only something is given about the magnitude) and, more important, nothing is said about the possibility of false alarms.
6. A paper on a multiparametric approach applied to the Ridgecrest earthquake has recently appeared (De Santis et al. Front. Earth Sc. 2020). I think it could be convenient to compare the results obtained here with those found in that paper.

Minor points

Please have a look at all indications on the amended pdf. Here I list only few of those indications, that I consider a little more important than others do.

7. I suggest a correction: instead of “… from 20-years perspective”, it would be better “from a 20-year perspective”.
8. The symbol indicating the location of the EQ epicenter does not seem red as said in the caption.
9. Please consider the same latitude-longitude limits in all four pictures.

Many other smallish mistakes or indications are present in the pdf file. Please also consider all to improve the quality of the manuscript.

 

Comments for author File: Comments.pdf

Author Response

First of all, we want sincerely thank the respected referee for the careful reading of the paper, permitting us to avoid unnecessary mistakes and miss prints.

If to say on the figures, most mistakes (except Cyrillic symbols in Fig. 2) were introduced during the original paper's conversion into the Atmosphere format without our participation. In the original version, the sign in Fig. 1 is in red, the panels in Fig. 10 are in proper order, the triangle in Fig. 6 is in the proper place, etc. So we will prepare all figures as separate package of figures with high resolution and send them separately from the text.

All language mistakes are corrected (thanks to the reviewer).

References to the De Santis et al., 2020 paper is added together with corresponding text inside the paper.

And finally, about the latitude-longitude limits. It is a difficult question because the figures were prepared by co-authors using the different software, and redrawing them within the short interval of 10 days looks problematic. It seems that it is not very important to understand the issue of the effect demonstrated. We will do our best, and probably some pictures could be corrected in a shorter time.

Now we return to the conceptual questions.

We agree that self-similarity needs additional attention with more precise determination. We will do this elsewhere, where we will present the technology of data processing. Here we replaced the self-similarity with close similarity.

Question 3. The precursor is not simply night-time positive deviation, but the continuous deviation starts after sunset and finishes the next day after sunrise. The positive deviation on DOY 250 appears near midnight, not after sunset. The deviations on DOY 303-304 are indicators of aftershock, not false alarms. And finally, DOY 205. Probably we will indicate in the figure by text that it is the effect of a geomagnetic storm. Just the precursor mask permits the visualization of the difference of the ionospheric precursors of the earthquake and geomagnetic storm effect (you can check the Dst graph). As we know, the effect of the geomagnetic storm in the ionosphere (especially for the critical frequency, has a positive and negative phase. So, the positive deviations on DOY 205 are marks of the positive phase of the geomagnetic storm.

Question 4. We should remind that the chemical potential variation is the process, not a single moment, and it starts well before the anomaly presented in Fig. 9. This anomaly is used to demonstrate the spatial distribution of this atmospheric anomaly for the purpose of earthquake epicenter location. To not overload the paper, we do not show the temporal evolution of ACP, but here we can present it. (Attached with name author-coverletter). We can see the sharp increase of ACP started on 20 of June.

Question 5. We agree. We will re-write this section of the paper to present a clearer technology of determination of all three earthquake parameters. We will touch on false alarms, but this is not necessary to discuss in detail in this paper. This paper's main task is to demonstrate the difference and similarity of the precursors for these two earthquakes only.

Thank you very much once more for the valuable comments which helped to improve the paper.

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper presents a comparative analysis of precursory phenomena in the ionosphere and atmosphere for two strong earthquakes of the same magnitude M=7.1 happened in the same area in a time interval of 20 years. The argument is very interesting and actual. The paper is well written, clear and exhaustive. I havent any suggestion for increasing the quality of the paper.

Author Response

Thank you very much for your comments

Reviewer 3 Report

I am delighted to review your study on comparative analysis of precursory occurrences for the two strong earthquakes of the same magnitude. Overall, the manuscript is well-written and worth exploring; however, I believe the following suggestions will be helpful for the future improvement of your manuscript.   

I suggest you improve your abstract by adding key results and findings.

I would like to start with one general comment for this paper. There is a tendency to use long sentences connected by commas or semi-colons which makes sometimes them difficult to reading. I would suggest a thorough copy editing; at times the language is stilted and there are a few instances of incorrect grammar usage. Please see a few examples at the end of the comments.

In the introduction, it would also be very helpful to include a paragraph toward the end of the first part to preview the structure of the paper as at some point it feels like the structure is missing.

In terms of methodology and results parts of this paper, the results are consistent with the data and can have significant implications in the industry of precursory researches.

In conclusion, the paper could be strengthened by adding some thoughts on how cognitive identification can be utilized to enhance the knowledge on ionosphere associated with seismic activity before a seismic event.  

A few examples of grammatical mistakes/corrections:

Line 62-63: please rewrite the sentence- “a certain group of fighters…….”. Fighters represent who?

Line 148-150: suggest rewrite the sentence.

Line 227-229: suggest rewrite the sentence.

Line 445-447: suggest rewrite the sentence.

Author Response

Thank you very much for your valuable comments. We made modifications inside the paper acoording your recommendations. 

Sincerely

The authors

Round 2

Reviewer 1 Report

The new version improved the original manuscript. However I have some other few concerns about the following points.

1. My previous #5 indications has been under-evaluated. Citation of De Santis et al. Fr.E.S. 2020 has been cited inappropriately in lines 263-268: from what is said, the impression about that paper is only negative. When the situation is not that. The 2-3 June anomaly taken by the ionosonde is not a weak anomaly. In addition, almost in the same time (from 1 day later) other satellite Swarm anomalies were detected independently. By the way, regarding the precursor time of 33-34 days is not too long, if considered the Rikitake law for that earthquake magnitude (please also see De Santis et al., Sc. Rep. 2019).  
2. I have concerns about the lines 441-459 where it is supported the existence of only very short precursor times of a few days. My opinion is that it is not the single anomaly which is important, rather a sequence (chain) of anomalies, whose starting time is longer for large magnitude (De Santis et al., Sc. Rep., 2019). Of course, this does not exclude the presence of anomalies appearing also very close to the earthquake occurrence. In fact, all the papers cited (Kon et al. 2011,  Li and Parrot 2013, 2015, ecc. [by the way, please note the mistake of the year of the 2013 citation]) actually took into considerations only short times of few days before the earthquakes.
3.  I would also ask the authors to evidence also all corrections that I pointed out in my pdf file, in order to better check all for sure. 

Author Response

• My previous #5 indications has been under-evaluated. Citation of De Santis et al. Fr.E.S. 2020 has been cited inappropriately in lines 263-268: from what is said, the impression about that paper is only negative. When the situation is not that. The 2-3 June anomaly taken by the ionosonde is not a weak anomaly. In addition, almost in the same time (from 1 day later) other satellite Swarm anomalies were detected independently. By the way, regarding the precursor time of 33-34 days is not too long, if considered the Rikitake law for that earthquake magnitude (please also see De Santis et al., Sc. Rep. 2019).  

The text where the reference (De Santis et al., 2020) is completely rewrited and extended, giving positive value of the reference (see lines 229-248 of the final version of manuscript)

• I have concerns about the lines 441-459 where it is supported the existence of only very short precursor times of a few days. My opinion is that it is not the single anomaly which is important, rather a sequence (chain) of anomalies, whose starting time is longer for large magnitude (De Santis et al., Sc. Rep., 2019). Of course, this does not exclude the presence of anomalies appearing also very close to the earthquake occurrence. In fact, all the papers cited (Kon et al. 2011,  Li and Parrot 2013, 2015, ecc. [by the way, please note the mistake of the year of the 2013 citation]) actually took into considerations only short times of few days before the earthquakes.

Just this concern of the respected referee was taken into account in mentioned above new text in lines 229-248 of the final version of manuscript

•  I would also ask the authors to evidence also all corrections that I pointed out in my pdf file, in order to better check all for sure. 

Takin into account that the new version has different lines number in comparison with the first one and it is difficault co copy the Refere''s comments to the new version, we attach the pdf file with comments of referee where in every comment frame our answer is give, We suppose , this will be satisfactory.

Author Response File: Author Response.pdf