Archeoseismic Study of Damage in Medieval Monuments around New Delhi, India: An Approach to Understanding Paleoseismicity in an Intraplate Region

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors,

The article presents a contribution to the evaluation of the seismic hazard of India, through the study of damage to historic buildings in the New Dehli area. I consider that the article is very well founded, since it presents abundant relevant citations in the area of study, the methodology is rigorous and the authors have managed to write a document that is pleasant to read, which is appreciated.

I have some small observations, practically of form, that would be interesting to fix before the document is publishable. Listed below:

1. On line 77 use the correct notation for Mw.

2. In Table 1, in the magnitude column, please indicate (when possible) the type of magnitude of the earthquake.

3. In the Figure 2 group, please indicate the source of the images used.

4. On line 154, indicate the basic value of the acceleration contemplated for seismic zone IV.

5. Add the source of Figure 3.

6. The quality of Figure 8 must be improved, allowing proper reading of its information. Additionally, authors must indicate the source of the images.

I have a doubt regarding the observations presented, the effect produced by axial forces on the constructions is evident, however, such obvious examples of the effect of shear stresses on this type of structures are not shown, which are expected under the action of earthquakes. What is the reason for this lack of information?

Author Response

Dear editors, dear reviewers,

we thank you for the patience and the excellent comments and remarks of the professional reviewers, please find our detailled response in the attached "response to reviewer" doc.

Many regards. KR

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

 

The ms discusses an archaeosismic study of various monumental sites in Delhi area.

While the paper has the potential to be interesting, the current observations aren't quite convincing enough to support the presented conclusions. In my view, the inferences drawn from the damages seem rather questionable.

To enhance the paper's overall coherence, I propose a reorganization, minimizing redundancies and repetitions:

1) Introduction, including details from paragraph 4

2) Seismotectonics sketch of the area

3) Historical seismicity of Delhi area (with some summary tables from catalogues)

4) Archeoseismological evidences

 

In my view the paper would be better focused on the archaeoseismic methodology rather than going too deep into seismic risk considerations. In fact, I observe that the inferences from the damage seem rather superficial and qualitative, It is crucial to justify the exclusion of alternative causes such as frost or aging, for instance. Numerous examples and numerical models regarding the damage to ancient structures are available in the literature, offering valuable insights.

Some sentences in the paper are too assertive, see lines 332-335, or 351-352. For improved clarity, the relationship between damage and the causative earthquake should be explicitly delineated, accompanied by textual information to original sources or other convincing data. Additionally, the description of damage timing is vague, requiring clearer evidence linking it to the earthquake. Furthermore images are not clear , and they do not really help in understanding the authors’ hypothesis. Provide better quality photos.

 

Some inaccuracies are identified in the text :

line 85 – “magnitude between VI-VII” It is inappropriate to use Roman numerals for magnitude. Better  magnitudes between 6 to 7.

line 450 – The notation of EMS intensity VI-V and VIII-VII, is likely a mistake. Correct notations are V-VI and VII-VIII

 

References list is redundant and requires a thorough review.

 

item 124 [Giuliani ] in the Reference list, is cited as 123 in the text, in tab. 3,

and similarly Fah is 123 instead of 122 in the text. Something has been skipped in the list.

References 92 and 115 are not cited in the text.

 

Is it possible to add some parametres in table 2, as local intensity, epicentral intensity, magnitude? If not, why?

 

 

Comments on the Quality of English Language

no comments

Author Response

Thank you very much for the comments, we have adjusted and corrected the manuscript according the suggestions

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

General comment:

The paper by Naik et al provides evidence of ground shaking damage on Medieval sites at New Delhi, India. Archeoseismic observations are supplemented with Shakemaps for 3 relevant historic earthquakes which have hit the region. The topic is certainly relevant, given the large vulnerability and exposed value in the region. I think the paper should undergo moderate revisions before publication.

More than half of the paper deals with a general introduction to the region and archeoseismology in general; original data (field surveys and shakepmaps) are briefly discussed, while instead they should be emphasized much more. Valuable new data are obtained from additional archeological sites beside Qutab Minar but it is not clear how this contributed to SHA, since all the sites are located close to each other – overall, I think the title part “contribution to SHA” promises more than what is achieved by the paper.

I suggest adding a proper Methods section, which now is totally missing. Here, the authors can describe the methods for field surveys and Shakemaps (i.e., the original data presented in the paper). I encourage the authors to discuss triggering mechanisms other than earthquakes: throughout the paper you claim that all the observed damage is coseismic in origin, but the readers have not enough information for evaluating by themselves. Finally, please take care of the pitfall of circular reasoning: you observe the damage, look at the earthquake catalogue and match the two. However, you also state that the seismicity is low and the amount of data is rather poor, so I would be more cautious in explaining the limitations – or enhancing where your interpretations are supported by strong arguments and where they are not.

Detailed comments:

Lines 20-22: check the grammar of this sentence

Lines 22-25: split the sentence in two, it is difficult to follow.

Lines 34-35: do you mean local intensities at the sites?

Line 61: delete “more or less”

Line 77: Mw instead of MW

Lines 78-81: it seems the same concept repeated twice, delete one of sentences or explain better

Line 85: magnitude should be expressed as Arabic numbers, i.e., magnitudes between 6 and 7.

Table 1: intensity is max intensity? Or local intensity in Delhi? Is it MM scale, right? Add it in the caption.

Lines 96-97: this sentence is not clear to me. Do you mean that none of the sites except Qutab Minar was analyzed in an archeoseismic perspective?

Line 102: here you state that Qutab Minar was damaged by the 1720 and/or (?) 1803 earthquake, while at line 95 you mention the 1803 earthquake only. Please clarify.

Lines 103-106: this part should be introduced before, like around line 88.

Lines 113-115: locate all the mentioned places/geological structures on a map

Line 154: not clear to me what is the “seismic zone IV”, are you referring to a nation-wide seismotectonic zonation?

Section 3: can you locate the epicenters of the mentioned earthquakes on a map? Maybe fig 3?

Line 193 (table 2): Tables 1 and 2 are somehow confusing to the reader, since they convey partially overlapping information. It is not clear which is the difference between the 2 tables, consider to merge into a single one.

Line 224: delete “if needed further”

Line 230: add a heading “3.4 recent earthquakes”

Lines 236-240: choose one format for the date and be consistent. In the text there are August 15^th, 1966; July 28 1994; 5^th march 2012 and so on.

Line 256: IS not easy due…

Section 4 (lines 248-272): this is background information, not specifically dealing with the original results of this study. I think this part can be shortened.

Lines 259-272: what the authors state is true, but also the challenges and limitations of archeoseismology should be mentioned: for instance, events other than earthquakes can damage archeological sites and the possibility of obtaining the seismic parameters (line 268) is not granted even in the presence of documented damage. Indeed, if you’re speaking about off-fault damage, several sites in a broad region are necessary to infer the characteristics of the seismogenic source.

Lines 274-283: this paragraph should come before, since it is a definition/introduction to archeoseismology. It does not belong to the section on “archeo evidence in India”

Lines 349-350: add ref. Do you mean on the MM intensity scale?

Lines 350-352: attention to the pitfall of circular reasoning (see general comment)

Line 385: typo in cupola

Line 414 (and more generally section 5): how did you rule out mechanisms or processes other than earthquake ground motion? Some of the features you documented may be suggestive of differential settlements or gravitative processes. You mention that some of the sites are on a riverbank, so on soft soil. I agree with you that ground shaking is a reasonable explanation for the observed damage, but you have to evaluate possible alternatives as well.

Lines 427-429: this sentence is an important outcome of your study but is not adequately demonstrated. You spent quite a lot in providing the general setting and an overview of archeoseismology, but you describe very briefly your original results and you did not explain how local intensity has been assessed.

Section 6: the generation of shakemaps is arguably the most original result of the paper. It should be emphasized way better, for instance by adding a proper methods section. Which are the input data, only location and magnitude? I bet you need also an intensity prediction equation: if this is the case, which equation did you chose? On which basis? How well-constrained are epicenter and M of historical earthquakes in such a relatively data-poor region?

Line 519: the last part of the sentence is not clear to me; are you stating that the reported intensity of the 1720 earthquake is overrated AND ALSO the 1803 is overrated? If I got it right, it seemed you ascribed all the observed damage to the 1802 qualke.

Comments on the Quality of English Language

minor suggestions are included in the detailed comments

Author Response

Thank you very much for the comments, we have adjusted and corrected the manuscript according the suggestions

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The authors addressed my previous comments in a more than reasonable way. I think the paper is ready for publication.