Singular Points of the Tremor of the Earth’s Surface

Round 1

Reviewer 1 Report

The author presents an analytical study of the singular points of the tremor of the earth’s surface in California. This reviewer has the following comments:

1    1)  This reviewer would suggest that the California’s location is included in the title of the paper.

2    2) Could the author draw the San Andreas fault in Figure 4? It would probably help the readers to correlate tremor singular points with the vicinity to the San Andreas fault.

3    3) The study covers the period 2009-2022. Isn’t it a too short period of time in seismic and geological terms?

4    4) Has the author any correlation of tremor results with seismograph measurements in California?

5    5)  Overall, the paper well deserves being published in Applied Sciences.

Author Response

Comment. This reviewer would suggest that the California’s location is included in the title of the paper.

Response. Done. Please look new variant of the paper.

Comment. Could the author draw the San Andreas fault in Figure 4? It would probably help the readers to correlate tremor singular points with the vicinity to the San Andreas fault.

Response. Thank you for this valuable comment. Done. Please look new variant of the paper. Besides that please look interpretation of singular points in the lines 269-284 and 327-331 in the new variant of the paper.

Comment. The study covers the period 2009-2022. Isn’t it a too short period of time in seismic and geological terms?

Response. Yes, this time interval is short in geological terms. However, you have to work with the data that is available. Although the history of GPS observations in California begins around 1992, the acceptable station density required for this analysis was not reached until 2009.

Comment. Has the author any correlation of tremor results with seismograph measurements in California?

Response. I have an experience of analyzing seismic noise is Southern California (https://link.springer.com/article/10.1007/s10950-020-09950-3) but it is rather difficult to compare very long-periodic daily GPS time series with much more high-frequency seismic noise.

Reviewer 2 Report

The paper describes a mathematical probabilistic method that analyzes a signal that the author call "tremor". The author identifies two types: active tremor and passive tremor which has both its own mathematical characteristics. I recommend this paper for publication in Geosciences after the author consider the following observations:

What is not described anywhere in the paper is that if the author is analyzing coherent noise registered in GPS series that can have multiple sources like thermal, cultural, wind, storm, etc or if the author is analyzing a seismic signal. In seismology the use of the term "tremor" is referred to volcanic harmonic seismic signals, called "Volcanic Tremor" and to the seismic signals caused by Slow Slip Events that are earthquakes that do not generate big shakes that happens in the transition zones of subducting tectonic slabs. This SSE emits a seismic signal called "Tectonic Tremor".

The author must clarify that he is not studying any tectonic phenomena but some kind of long period surface waves (?) that can be detected by GPS. 

Also is not clear for me what is the physical source of "passive and active tremors". Try to give a physical explanation for this phenomena that can be a complement to the mathematical definition that the author describes in the abstract and method section.

Minor suggestions:

1) Author must show the grid he is using in a map.

2) Labels in figure 3 are too small to read.

I attach the PDF with the paper with some comments.

Try to pass the text through grammarly so some sentences get clearer.

Author Response

Comment. What is not described anywhere in the paper is that if the author is analyzing coherent noise registered in GPS series that can have multiple sources like thermal, cultural, wind, storm, etc or if the author is analyzing a seismic signal. In seismology the use of the term "tremor" is referred to volcanic harmonic seismic signals, called "Volcanic Tremor" and to the seismic signals caused by Slow Slip Events that are earthquakes that do not generate big shakes that happens in the transition zones of subducting tectonic slabs. This SSE emits a seismic signal called "Tectonic Tremor".

Response. I tried to take into account this comment. Please look lines 40-47 in new version of the paper.

Comment.  The author must clarify that he is not studying any tectonic phenomena but some kind of long period surface waves (?) that can be detected by GPS. Also is not clear for me what is the physical source of "passive and active tremors". Try to give a physical explanation for this phenomena that can be a complement to the mathematical definition that the author describes in the abstract and method section.

Response. I tried to take into account this comment. Please look lines 17-18, 269-284 and 327-331 in new version of the paper.

Comment.  Author must show the grid he is using in a map.

Response. Done. Please look Figure 1 in the new version of the paper.

Comment.  Labels in figure 3 are too small to read.

 Response. I tried to increase all text labels as much as possible. Please look Figure 3 in new version of the paper.