Evidence of Widespread Volcanic Activity near Hebrus Valles on Mars Revealed by SHARAD

Round 1

Reviewer 1 Report

Dear Editor,

The paper, Evidence of widespread volcanic activity.. by Nerozzi et al. is a valuable analysis and interpretation of SHARAD data and should be published. The description of methods and use of instruments will be of strong interest for the journal readership.

I suggest the authors move the end of the introduction to the start of conclusions, for better flow. And they should elevate their conclusion that the Hebrus valley deposits have similar properties to other potential volcanic ash deposits, extending the reach of this deposit on Mars.

Introduction, first paragraph - could you point to your context figure for some of these descriptions? Or provide a new figure with some of these features labeled.

Line 47 - In-situ resource utilization is certainly an important aspect of current shallow water ice on Mars. There are many others, at least some of which should be listed and/or discussed here to boost the strictly scientific importance.

Line 53 - 65 - There is a lot of almost abstract-like conclusions in this Introduction. Typically, Introductions are good for background and information about the region aside from your work, and having all the conclusions up front (aside from in an abstract) interrupts the flow and basis for storytelling. I suggest leaving this material for later in the paper.

Line 81 - no need for "state of the art" - the reader assumes you are using sufficient software to do the job you need. Better to say what exactly the software is and what it does.

Line 91 - do you have a reference for the ideal nature of the software for SHARAD data (has something been published yet using these data)?

Figure 2a, what are the small pink lines? In addition to the clusters being labeled, state that they are outlined by distinct colors (do these colors mean anything?).

Figure 4 - what do you mean by mapped reflectors? Are the radar returns strictly these thin lines?

Line 329 - and following - This is an interesting argument. How does this location compare with one potential source of the MFF, Apollinaris Patera?

Line 347 - this is where you could put that material that is currently at the end of the Introduction.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors, based on Mars SHARAD radar data, computed the dielectric property parameters of the Hebrus Valles region, primarily focusing on inverting the distribution of the loss tangent. They discussed traces of volcanic activity in the Hebrus Valles and argued that the predominant geological activity in the region is related to Martian remolding. The paper has a logical structure, uses appropriate language, and is of interest in the field of Martian radar. I believe it is a work worthy of publication. However, there are also areas that need improvement. Detailed comments are as follows:

1. Line 29. SE needs to be spelled out in full. The first sentence needs a citation.

2. Abbreviations in Figure 2's caption should be spelled out in full.

3. Line 74. The author mentions the "U.S. SHARAD" product. The author needs to explain why this product was chosen, its advantages, and how it differs from other products. This should be made explicit.

4. Lines 104-111 should further elaborate on the advantages, disadvantages, and differences between the two different methods for calculating the loss tangent.

5. Table 1. There is a noticeable difference in the calculated loss tangent using two different methods. What is the reason for this difference? Which method is more suitable for this study? The author needs to clarify this.

6. When using the Power Ratio method, the author needs to assume a value for the surface permittivity. Surface permittivity may vary spatially, and terrain roughness could also affect the estimation of surface permittivity. Has the author discussed the impact of surface roughness on the inversion of the loss tangent?

7. In Figure 3a, the author presents a graph of energy vs. time. Did the author consider selecting values at peaks or troughs when choosing the energy of the subsurface surface reflections? If peak and trough values were selected, the distribution of energy points on the time axis would be at regular intervals, depending on the SHARAD's time intervals. If the author did not do this, please assess the differences between the two approaches.

8. What is the R2 value obtained when fitting the loss tangent?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf