Specific Effects of the 1988 Earthquake on Topography and Glaciation of the Tsambagarav Ridge (Mongolian Altai) Based on Remote Sensing and Field Data

Round 1

Reviewer 1 Report

The paper is acceptable in its present form

Reviewer 2 Report

The authors have responded very well to the comments of the reviewer for the manuscript remotesensing-1560370 and revised the manuscript accordingly. I have no further comments.

Reviewer 3 Report

Dear Authors,

I had the opportunity to review the new version of your manuscript. I believe you fully addressed my comments in the text and rebuttal letter; I particularly appreciate the new Fig 5, which clearly shows the behavior of glacier 15 with respect to neighboring ones.

From my side, the paper is ready for acceptance.

Best regards

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The paper by Agatova et al investigates a glacial collapse occurred in the Tsambagarav Ridge following a M 6.4 earthquake in 1988. Multi-temporal satellite images, supplemented with field surveys, are used to assess the changes through time of the area. Glacier n. 15 suffered ice detachment and lost a significant part of its area after the seismic event; comparison with nearby glaciers show a higher retreat of glacier n. 15.

The paper is properly organized and results are adequately described; in some instances the paper should be more concise. The case study is of regional relevance; some additional effort in the discussion/conclusions should be undertaken to put the case study into a broader context. Below I list my comments; overall, I believe moderate revisions are needed before recommending publication.

• Line 15: “collapse of part of the glacier…”
• Line 55: change to “by the Kobdo fault”
• Line 60 (figure 1): add the 1988 earthquake epicenter. Consider also to add historical seismicity, since you mention in the text the high seismicity of the region
• Line 66: as a resul of THE
• Line 77: superscripts for million and m3
• Line 80: detailed instead of detail
• Lines 92-93: which intensity scale, MSK, MM? I personally prefer Roman numbers for macroseismic intensity (i.e., from intensity VII to XI-XII), but it’s a minor detail
• Line 95: change seismic fractures to surface faulting. “Deep” is not completely clear to me, maybe change to active? Deep is sometimes used to indicate blind faults, which is not the case for the Altai region.
• Line 103: add Achit-Nur location in fig 1
• Line 116 (fig 2): add the approximate height of seismogenic scarps.
• Line 121: change the reference format
• Line 124: “is maximum in size”… is part of the sentence missing? Or do you mean that valleys on the N slope are bigger than on the S slope?
• Line 165: “applying different approaches”. Please explain
• Line 262: add some info on the Ulgy meteo station: how far is it from the study area? Which is the elevation?
• Line 268: I think it could be useful to see a plot similar to Fig 5a also for glaciers n 16 and 17. These data can enable a comparison through time among neighboring glaciers, highlighting the relative role of seismic trigger and of more recent glacier retreat. The comparison between 1968 and 2016 images in figure 9 is really clear, but I’m wondering if glaciers other than n. 15 have the same pattern of area loss after 1988 (i.e., did the earthquake somehow affected glaciers 16 and 17 even though it did not cause a collapse?)
• Line 273: 1988 instead of 1998
• Line 286 (section 3.3): add a few words on accuracy and resolution of GlabTop model (but consider I’m not familiar with the topic, so take it as an optional suggestion).
• Line 325-326: this sentence is not clear to me, please rephrase. The new river channel is located toward the gentler slope of the valley?
• Line 380: change reference format
• Line 429: events instead of event
• Line 449: table caption is missing
• Lines 489-492: glacier n. 15 is the only one undergoing significant ice detachment following the seismic event. Peculiar characteristics of glacier n. 15 and possible causes for its behavior are mentioned in different parts of the paper (e.g., lines 134, 443, 489-492, 540). This dispersion may distract the reader’s attention. Consider the possibility to put all these parts together in a dedicated section.
• Line 521: is it m3 or km3?

Reviewer 2 Report

Brief summary:

The manuscript analyzes the influence of an earthquake on the retreat of a glacier. Changes in the glacier area are determined from satellite images and changes in the mass balance are estimated using weather data and the firn line altitude. The glacier is visited twice to carry out field measurements and to see the environment. The calculations are based on previously derived experimental relations between different quantities. Possible explanations for the initiation and passing of an ice-rock avalanche shortly after the earthquake are suggested, based on the documentation of the avalanche in [16] and further thoughts in [11].

General comments:

The manuscript supplements the previous studies on the ice-rock avalanche with a follow-up of changes in the area for the subsequent three decades and provides new convincing ideas for the avalanche mechanism, so the manuscript advances current knowledge. The manuscript is well structured, clearly presented, and technically correct apart from a few typos. The conclusions are justified.

Detailed comments:

Lines 57, 66, and 475: If the main chock was on July 23 and the avalanche on August 9, then the avalanche was 17 days after the main chock and not 13 days.

Lines 89 and 149: The sections for the study area and for the methods have the same section number.

Lines 273-275 and Fig. 5: The seismic event was in 1988 and not in 1998, while the abrupt decrease of the mass balance was in 1998. 

Figure 9: There is a conflict between the acquisition year 2015 of The World-View-2 satellite image and the figure label 2016.

Lines 456-461: Are you sure that the collapse in 1988 was the main reason for the acceleration of the retreat in 1998? Were glaciers no. 16 and 17 equally thick as glacier no. 15? If glacier no. 15 was thinner than the other glaciers and all glaciers lost an equal volume, then the area lost by glacier no. 15 would be larger. This could be another explanation for the faster retreat measured in terms of the area of the glacier.

Lines 506 and 520-521: "6 million km3" should be "6 million m3".

Lines 552-555: Essentially the same sentence appears twice.

Line 570: Your first visit was not in 1988 but in 2004.

Reviewer 3 Report

The paper presents an interesting case study of glacier movement in the Tsambagarav ridge (Mongolian Altai). Even though the case is interesting and some interesting photos and figs are given, its description must be improved:

-Typographic errors exist, for example in table 1 and Fig. 5 captions.

-In Fig. 3 the symbol 15 is given two times, in the glacier number and in the caption, and this may confuse the reader

- The earthquake, which according to the authors triggered the glacier, is not described well (location, maximum acceleration etc. are not given).

-The geology of the mountain rocks is not described adequately

-Cross-sections are useful in representing movement and required for possible 2-D analyses of movement (Seed et al., 1975, Ambraseys and Srbulov, 1995, Di et al., 2017). Thus, it is recommended by the authors to present such cross-sections of glacier 15.

References

 Seed H.B., Lee K. L., Idriss I. M., Makdisi F. I. (1975): “The slides in the San Fernando Dams during the earthquake of February 9, 1971,” Journal of Geotechnical Engineering ASCE; Vol. 101, No. 7, pp. 651-689.

Ambraseys N., Srbulov M. (1995): “Earthquake induced displacements of slopes,” Soil Dynamics and Earthquake Engineering; No. 14, pp. 59-71.

-Di Β., Stamatopoulos C. A., Dandoulaki M., Stavrogiannopoulou E. Zhang M., Bampina P. (2017). A method predicting the earthquake-induced landslide risk by back analyses of past landslides and its application in the region of the Wenchuan 12/5/2008 earthquake, Natural Hazards, January 2017, Volume 85, Issue 2.