|Some important clarifications, revisions, and improvements have been made in this version of the manuscript. However, in many cases, it was apparent that “changes” made in response to referee comments did not actually address the point made by the referee. In other words, changes were made, but they were irrelevant or partially relevant to the referee comments. In other cases, referee suggestions appeared to be outright declined. The following is a list of the most offensive examples of comments that were not duly considered and a short explanation of how the response was insufficient for each:|
1) Original Referee Comment: “Introduction: the structure of the introduction is awkward, particularly because it immediately jumps into site description…”
Why the response is insufficient: No action was apparently taken in response to this comment. Rather, the author attempts to justify a poorly organized introduction by saying the site is the most important thing. This argument is flawed – a well organized introduction will not detract from the importance of various study components. A well organized introduction will certainly improve readability and comprehension by readers. Placing something “first” in the text has no effect of making it appear “more important.”
2) Original Referee Comment: “Page 2, Line 33-34 & Page 3, Line 1: While I certainly agree that ERT is sensitive to fluids as indicated here, this justification for the ERT method seems incomplete because the several earth properties that control resistivity can be difficult to tease apart to attribute.”
Why the response is insufficient: The response indicates that a table is not included (not requested in the review comment) and logging data has been added (also not requested). The remainder of the response is primarily statements unsupported by evidence. An explanation of how the various material properties can be determined from resistivity as requested was not attempted.
3) Original Referee Comment: “P8-L10-12: As indicated above, the nature of ERT interpretations is that these several properties all affect the measurement together…”
Why the response is insufficient: This is essentially the same comment as in #2 above, and the author response is essentially the same. While saturation, porosity, fluid conductivity, and clay content all contribute to the total observed resistivity, the author only partially addresses porosity. This is central to the interpretation of the manuscript because presumably the gas-phase they a looking for will have an impact on saturation, and pore water conductivity is unknown – these properties would certainly effect the total resistivity, however there is no adequate discussion of the point at all in the revision.
4) Original Referee Comment: “Figure 2: I suggest either merging this with Figure 1 or Figure 3 to make a 2-panel figure, OR perhaps merging all three to make a single 3-panel figure.”
Why the response is insufficient: The only change made was the re-order the figures. The justification given for not addressing the review comment is that “each figure is so important.” To be completely clear: there is NO relationship between the “size or location of the figure” and “the importance of the figure.” How could combining the three separate figures into one figure with three panels possibly detract from their importance? Combining figures that are similar or have similar context is an important tool to improve readability – it will not make the information seem less important.
4) Original Referee Comment: “Page 14, L3-4: What figure does this refer to? I assume #6. “appears significantly smoother” Smoother than what? How do you know it is “significant”? If referring to Fig 6, left panel, then I disagree – if the authors intend to make this argument, then it should be supported by a quantified metric. ”
Why the response is insufficient: The review comment specifically requested a quantified metric to support the argument. This was outright ignored – no quantification is provide in the reformulated sentence.
5) Original Referee Comment: “Page 22, Line 3: “At at least one spot along our profile, the HMF, these fluids can propagate to the surface through the Tertiary sediments, but also at other sites expressions of fluid flow can be observed. ” Please explain how this can be observed in the data measured for this experiment. ”
Why the response is insufficient: The referee comments specifically requests that the author explains how this can be observed in the data measured from this experiment, however the response does nothing more than rephrase the sentence – there is still no indication of how this effect is directly interpreted from data or figures presented in the manuscript. Please explain how the data presented in this manuscript shows that fluids can propagate to the surface through tertiary sediments.
6) Original Referee Comment: “Page 23, Line 3: Figure 11 should be explained in the discussion, not conclusion. The conclusion section contains "summary" content and "discussion" - please rewrite this to focus on only concluding remarks.”
Why the response is insufficient: The response explains a formatting error related to the placement of the figure: this is completely unrelated to the content of the comment which suggests ways to improve organization of the text.
In addition, I remain unconvinced that this manuscript should be cast under the topic of “fluid pathways” as suggested by the Objective 2(p.6), and alluded to in the title. This point was made by both reviewers, but was ultimately not sufficiently addressed by the author. This is claimed to be accomplished in Figure 9, specifically through annotation with arrows that show interpreted fluid flow pathways. However there is no evidence in the geoelectrical image (Figure 8) of either 1) the PPZ/HMF nor 2) anything that could lead to the interpretation of the fluid flow arrows. Of course, the authors state in the abstract that “Distinct, narrow pathways for CO2 ascent are not observed with this kind of setup which hints at wide degassing structures over several kilometers within the crust instead.” However this apparently contradicts what is indicated in the Fig 9 cartoon that shows CO2 movement along specific, narrow conduits.
Finally, the conceptual Figure 9 is essentially a redrawn version of the borehole cross section with resistivity values added for each lithology. Confusingly, the spatial variability of resistivity is noted in the labels (apparently following the associated comments in the Interpretation section), but each lithology is drawn in the same color so it is not possible to actually tell how the resistivity values are distributed as shown in the Figure 8 imaging. This leads back to another reviewer comment that was not adequately addressed: what value has the ERT image actually brought to the conceptual subsurface understanding? It seems that everything the authors want to interpret is taken from the borehole cross section (e.g., discrete CO2 flow pathways that are not visible on the ERT image; overall subsurface structure and lithology that is better resolved by boreholes than from ERT; a 100 ohm m block is inferred on the conceptual model that was not observed in drilling, however it apparently has very little to do with fluid flow).