Imaging Arctic Permafrost: Modeling for Choice of Geophysical Methods

Round 1

Reviewer 1 Report

General comments:

This paper compared the different potentialities of Electrical resistivity tomography, Seismic Surveys and Shallow transient Tomography (sTEM) geophysical methods for imaging the permafrost base and geometry, vertical fluid conduits (permeable zones), taliks, gas pockets, and gas hydrate accumulations in the continental Arctic areas, and got some interesting and useful results. This paper has a reasonable structure and is standardized in writing. There are only some minor modifications needed before published in Geosciences.

Suggestions：

 （1）There are too many keywords in an article,which will weaken the meaning of the keywords themselves. It is suggested that the number of keywords should be reduced and condensed, the number range from 3 to 8 is appropriate.

（2）In general, citations should not be included in the conclusion. It is recommended to insert them in the discussion section and number the conclusion.

Author Response

Dear Editors and Reviewer,

We greatly appreciate the reviews and valuable comments, which helped us to improve the manuscript. In the revised version, we tried to follow the reviewers’ suggestions as much as possible.

Please, find the reply to specific comments below.

Reviewer 1

 （1）There are too many keywords in an article,which will weaken the meaning of the keywords themselves. It is suggested that the number of keywords should be reduced and condensed, the number range from 3 to 8 is appropriate.

Corrected

The key words are now as follows: Arctic; permafrost; gas hydrates; seismic surveys; resistivity surveys; electrical resistivity tomography; transient electromagnetic soundings.

（2）In general, citations should not be included in the conclusion. It is recommended to insert them in the discussion section and number the conclusion.

Corrected.

Thank you and best regars!

Author Response File: Author Response.doc

Reviewer 2 Report

 

Review of

Mapping Arctic Permafrost: Potentiality of Geophysical Surveys

The authors have tried to find the suitability of the different geophysical survey techniques for mapping the arctic permafrost. There are minor issues in the manuscript given as follows:

·       The research gaps should be elaborated.

·       Some real images of the field can be added. It will add significant value to the paper.

·       The accuracy of the techniques used in the papers should be added.

·       L39-L42: The sentence seems complicated. It should be modified.

·       L 54-55: Reframe the sentence

·       L100-101: Clear the meaning of this line

 

Author Response

Dear Editors and Reviewer,

We greatly appreciate the reviews and valuable comments, which helped us to improve the manuscript. In the revised version, we tried to follow the reviewers’ suggestions as much as possible.

Please, find the reply to specific comments below.

 

The research gaps should be elaborated.

The respective section has been revised correspondingly.

 Some real images of the field can be added. It will add significant value to the paper.

In this paper we’re modeling synthetic data. Since we have no our own seismic and ERT field data yet, we use published field results (Boikov, 1973; Bogolyubov et. al, 1984; Zykov, 1999; Yakupov, 2008; Melnikov et al., 2010; Skvortsov et. al, 2011). The campaign is planned for the year 2023, and the results will be reported in a separate publication.

As for the TEM field data, they were published recently and cited (Buddo et. al., 2017; 2022; Misurkeeva et. al, 2017; 2019; 2020; 2022).

We thought citing would be enough for the reader to find and look into the data if necessary. However, we have added the published image (Fig. 11).

• The accuracy of the techniques used in the papers should be added.

Shallow seismic surveys are commonly accurate to a few meters; the resolution can be even higher if the acoustic properties of rocks are contrasting enough.

DC methods allow mapping resistivity layers of a few meters thick provided that the resistivity contrast is sufficient.

Inversion of TEM signals yields high-resolution models of shallow sediments with layers thicknesses from 5 m to tens of meters at depths of 300-400 m.

 

The respective information has been added to Methods.

         L39-L42: The sentence seems complicated. It should be modified.

Corrected. Rephrased to More complexity has been due to lithological heterogeneity and permeability of deformed freezing sediments: neotectonic deformation of such sediments produced conduits for gaseous and aqueous fluids as a prerequisite for the formation of intra- and sub-permafrost gas hydrates.

  L 54-55: Reframe the sentence

Corrected. Rephrased to Nevertheless, those data made basis for models that image permafrost to depths of a few tens of meters [15, 16].

 L100-101: Clear the meaning of this line

Corrected. Rephrased to The pressure and temperature in thick permafrost, both on the shore and in the shelf, correspond to the conditions of gas hydrate stability [30].

Thank you and best regards!

Author Response File: Author Response.doc

Reviewer 3 Report

The manuscript has 15 pages, 72 references, 10 figures, 1 table. The consistent is high quality. Authors show geophysical-geological model of northern West Siberia to a depth of 400 m, which includes modern permafrost, lenses of relict permafrost with hypothetical gas hydrates, and a permeable zone that may be a path for migration of gas-water fluids. The permafrost of northern West Siberia had a complex history. The model was used to model synthetic seismic, electrical resistivity tomography (ERT), and transient electromagnetic (TEM) data and thus test the advantages and drawbacks of the three methods. The complex of methods are needed some electrical methods are poorly applicable to the mapping of permafrost reaching hundreds of meters thick.

 

Comments:

 

The title contains “Arctic”, however, mostly I see Yamal-Nenets or Northern West Siberia, because, the models and idea of applicability is shown in West Siberia, not Yakutsk for example.

 

I also am not agree with title “Potentiality of Geophysical Surveys”, because there are a lot of papers before, that prove the potential geophysical methods, especially electromagnetic, efficient for ice and permafrost soundings. See below.

 

 

Zadorozhnaya, V. Yu. "Transient EM sounding in the study of permafrost." Permafrost--7th International Conference. Yellowknife, Canada. 1998.

Melchinov, V. P., and A. A. Pavlov. "Experience with a Water Detector in the Study of the Permafrost Structure." Geomagnetism and Aeronomy 62.3 (2022): 271-277.

Yakovlev, D. V., A. G. Yakovlev, and O. A. Valyasina. "Permafrost study in the northern margin of the Siberian platform based on regional geoelectrical survey data. J." Earth’s Cryosph 12 (2018): 67-84.

Kozhevnikov, N. O., et al. "TEM surveys for search of taliks in areas of strong fast-decaying IP effects." Russian Geology and Geophysics 55.12 (2014): 1452-1460.

Петров, А. А. "Возможности метода становления электрического поля при поисках углеводородов в шельфовых зонах." Геофизика 5 (2000): 21-26.

 

In metadata there are some mistakes. Before the city – ZIP code. Ivan Shelokhov 1 “comma” 2 “comma” 3.

 

Citation at the left column – metadata check.

 

I see the paper Misyurkeeva N, Buddo I, Shelokhov I, Smirnov A, Nezhdanov A, Agafonov Y. The Structure of Permafrost in Northern West Siberia: Geophysical Evidence. Energies. 2022; 15(8):2847. https://doi.org/10.3390/en15082847 , which mostly explains the total text and resistivity model and geographical placing. Why this citation is missed? Maybe it is better to cite than [39] proceedings?

Line 53 DС resistivity – is an abbreviation first mentioned. Anywhere authors need to explain full term.

Line 153 I don’t understand what is “Tibey-Sale Fm”. This is an only one mention.

Line 165 Georadar instead of upper “ground penetrating radar (GPR)” from line 161.

Line 211 needs a reference citation for “ZondRes2D”.

 

As I see from authors’ previous works - Figure 2. Geological model of certain permafrost is taken from real geologic conditions. So why not to refer to this special place (deposit)?

Figure 3. Which tool? (name, manufacturer )

Figure 4. Starting model for inversion of seismic data.

Line 235 – title for the figure should be near the figure.

Line 292 (Fig. 9 C). There is no 9 C, only 9 or 10 C.

Author Response

Dear Editors and Reviewer,

We greatly appreciate the reviews and valuable comments, which helped us to improve the manuscript. In the revised version, we tried to follow the reviewers’ suggestions as much as possible.

Please, find the reply to specific comments below.

The title contains “Arctic”, however, mostly I see Yamal-Nenets or Northern West Siberia, because, the models and idea of applicability is shown in West Siberia, not Yakutsk for example.

Right, the study area is located in northern West Siberia, but the Yamal-Nenets district geographically belongs to the Arctic zone of the Russian Federation. Therefore, we believe data from this area illustrate well the processes and setting of the Arctic.

I also am not agree with title “Potentiality of Geophysical Surveys”, because there are a lot of papers before, that prove the potential geophysical methods, especially electromagnetic, efficient for ice and permafrost soundings. See below.

Zadorozhnaya, V. Yu. "Transient EM sounding in the study of permafrost." Permafrost--7th International Conference. Yellowknife, Canada. 1998.

Melchinov, V. P., and A. A. Pavlov. "Experience with a Water Detector in the Study of the Permafrost Structure." Geomagnetism and Aeronomy 62.3 (2022): 271-277.

Yakovlev, D. V., A. G. Yakovlev, and O. A. Valyasina. "Permafrost study in the northern margin of the Siberian platform based on regional geoelectrical survey data. J." Earth’s Cryosph 12 (2018): 67-84.

Kozhevnikov, N. O., et al. "TEM surveys for search of taliks in areas of strong fast-decaying IP effects." Russian Geology and Geophysics 55.12 (2014): 1452-1460.

Петров, А. А. "Возможности метода становления электрического поля при поисках углеводородов в шельфовых зонах." Геофизика 5 (2000): 21-26.

We agree. Actually, the main idea of the paper is permafrost imaging from different geophysical data with reference to an assumed geological model. The title has been changed to Imaging Arctic Permafrost: Modeling for Choice of Geophysical Methods

In metadata there are some mistakes. Before the city – ZIP code. Ivan Shelokhov 1 “comma” 2 “comma” 3.

Corrected

Citation at the left column – metadata check.

We expect MDPI editors to do this in the final design of the manuscript.

I see the paper Misyurkeeva N, Buddo I, Shelokhov I, Smirnov A, Nezhdanov A, Agafonov Y. The Structure of Permafrost in Northern West Siberia: Geophysical Evidence. Energies. 2022; 15(8):2847. https://doi.org/10.3390/en15082847 , which mostly explains the total text and resistivity model and geographical placing. Why this citation is missed? Maybe it is better to cite than [39] proceedings?

Agree. We have cited this publication instead of former ref. 41.

Line 53 DС resistivity – is an abbreviation first mentioned. Anywhere authors need to explain full term.

Corrected (spelled out).

Line 153 I don’t understand what is “Tibey-Sale Fm”. This is an only one mention.

Agree. Changed to dark-grey micaceous silty clay with sand and silt layers.

Line 165 Georadar instead of upper “ground penetrating radar (GPR)” from line 161.

Correcred

Line 211 needs a reference citation for “ZondRes2D”.

Reference provided:

http://zond-geo.com/software/resistivity-imaging-ves/zondres2d/  (last access on 09 October 2022)

As I see from authors’ previous works - Figure 2. Geological model of certain permafrost is taken from real geologic conditions. So why not to refer to this special place (deposit)?

The geological model does include some elements based on previous data (intervals of permafrost, hypothetical gas hydrates, unfrozen rocks, and a gas conduit). However, the model and its elements are generalized rather than being related to any specific field.

Figure 3. Which tool? (name, manufacturer )

Unfortunately we don’t have detailed information on the sonic log equipment (tool name and manufacturer), as the data we used were only archived LOG files, where no such information was provided. Presumably, it may be Techcom AVAK-7 (Russia), a standard logging tool used commonly in most of West Siberian oil fields. However, being not sure, we cannot refer to it in the text.

Figure 4. Starting model for inversion of seismic data.

Changed to Starting velocity model for seismic data.

Line 235 – title for the figure should be near the figure.

We expect MDPI editors to place properly all figures and captions in the final design of the manuscript.

Line 292 (Fig. 9 C). There is no 9 C, only 9 or 10 C.

Corrected.

Thank you and best regards!

Author Response File: Author Response.doc