the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 28 Jul 2026
Why are plate suture zones on the Tibetan Plateau hotspots for rockslides: A case study of Jinsha River area
Abstract. Tectonic suture zones on the Tibetan Plateau, as structurally weak belts, commonly host numerous large to very large rockslides. However, how the material composition and structural architecture of suture zones govern the initiation and evolution of landslides remains poorly understood. This study focuses on the Jinsha River suture zone (JSSZ). Through systematic field geological investigations, laboratory microstructural analyses, and landslide inventory statistics, we elucidate the control of tectonic mélange belt lithology and structure on landslide development, and construct a four-stage dynamic conceptual model from initiation to triggering. The results indicate that the heterogeneous, weak lithologies and complex structures of the suture zone provide the fundamental material and structural basis for landslide initiation. Sliding surfaces are not randomly distributed but predominantly localized along sub-horizontal foliation planes or lithological interfaces. These pre-existing discontinuities, under tectonic uplift and river incision, become preferential pathways for stress release and progressive weakening, resulting in clustered landslide distribution along the suture zone. Accordingly, a four-stage initiation and evolution model is proposed, systematically explaining the complete dynamic process from suture zone formation establishing the material-structural framework, through tectonic uplift and river incision driving rock mass fracturing, freeze–thaw cycles and chemical weathering causing progressive coalescence of the sliding surface, to final triggering of catastrophic failure. This study reveals the fundamental control of suture zone lithology and structure on landslide initiation, shifting the analytical perspective from short-term triggers to long-term dynamic coupling, and from external driving conditions to intrinsic lithological-structural constraints. The findings provide a new theoretical framework for understanding clustered rockslide development on the Tibetan Plateau and similar active orogenic belts, and offer a material-structure-based assessment basis for major engineering site selection and early risk identification.
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RC1: 'Comment on egusphere-2026-3016', Anonymous Referee #1, 07 Aug 2026
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AC1: 'Reply on RC1', Ming Wang, 20 Oct 2026
Thank you very much for this insightful and constructive comment. We appreciate the reviewer’s careful evaluation of the relationship between regional tectonic inheritance, slope-scale deformation, and large rockslide development. We agree that understanding how inherited geological structures influence slope instability requires consideration of geological structures across multiple scales, from regional tectonic settings to slope-scale discontinuities.
Regarding the concern about the lack of macroscopic structural analysis, we appreciate this important suggestion. We acknowledge that the original manuscript did not sufficiently emphasize the connection between field-based structural observations and the localization of potential sliding surfaces. In fact, our field investigations have documented various macroscopic structural features, including faults, foliations, joints, lithological contacts, and tension cracks. However, their role in linking regional tectonic inheritance with slope-scale deformation was not adequately highlighted in the original manuscript.
In the revised manuscript, we will strengthen Section 4.2 by incorporating and further interpreting these field-based structural observations, including representative discontinuity orientations and their spatial relationships with lithological contacts and potential sliding surfaces. These revisions will better establish the linkage between regional structural inheritance, slope-scale deformation, and microscale weakening processes. We will also clarify that these observations provide geological constraints on the preferential localization of sliding surfaces, while acknowledging that a more systematic quantitative structural inventory would further improve the understanding of structural controls on large rockslide development.
We also appreciate the reviewer’s comment regarding the interpretation and scope of the conceptual model presented in Fig. 6. We agree that processes such as unloading, weathering, fracture propagation, and slope deformation are not unique to suture zones and may also occur in other high-relief mountain belts. The key implication of our study is not that these deformation processes represent exclusive characteristics of suture zones, but rather that suture zones commonly preserve a favorable geological environment characterized by tectonic mélanges, heterogeneous lithologies, and inherited discontinuities, which may influence the preparation and localization of large rockslides.
To avoid overgeneralization and better clarify the scope of our conceptual model, we will revise the description of Fig. 6 and the related discussion in Section 5.2. Specifically, we will modify the title of Fig. 6 from “Schematic diagram of the preparation and evolution model of rockslides in suture zones” to “Conceptual model illustrating the role of suture-zone geological inheritance in the preparation and evolution of large rockslides”. We will also revise the description of the four-stage conceptual model to emphasize the role of suture-zone geological inheritance rather than representing an exclusive evolution pathway of rockslides in suture zones.
Regarding the possible role of toppling proposed by the reviewer, we appreciate this important consideration. We acknowledge that gravity-driven deformation, including toppling, may generate secondary shear zones during long-term slope evolution. However, our study does not intend to attribute all observed deformation structures exclusively to regional tectonic processes. Instead, we focus on evaluating how inherited geological structures may influence the preferential localization of potential sliding surfaces. We will clarify this point in the revised manuscript and acknowledge that gravity-driven deformation may interact with inherited geological structures during slope evolution.
These revisions will improve the balance between the geological evidence presented and the scope of our interpretation, and will help clarify the respective roles of inherited geological structures and subsequent slope-evolution processes in large rockslide development. We sincerely appreciate this comment, which has helped us refine the interpretation and improve the clarity of the conceptual model.
Citation: https://doi.org/10.5194/egusphere-2026-3016-AC1
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AC1: 'Reply on RC1', Ming Wang, 20 Oct 2026
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RC2: 'Comment on egusphere-2026-3016', Anonymous Referee #2, 14 Sep 2026
The paper by Zhou et al investigates two large rockslides in the Jinsha River area through field surveys and thin section analyses, to decipher the factors controlling landslide occurrence, ultimately proposing a theoretical framework. The topic is certainly of interest to the journal audience, however I think the paper requires major revisions to meet the criteria for publication.
The conclusions are ambitious and far-reaching, but the data presented here do not fully support such claims. An explicit definition of suture zones is lacking; by definition, tectonic melanges are highly heterogeneous, so a proper definition of the type of settings that can be analyzed using the proposed framework is relevant.
I think some rephrasing and providing more nuanced statements (e.g., last part of the abstract) could better reflect the paper contents. Indeed, the authors present their work as a new theoretical framework. If this is the case, the authors should better explain which is the novel content of the proposed framework and why the Jinsha river area is a reliable place to develop such framework. Moreover, their interpretations are based on 2 field sites only, which may be not enough to grasp the variability of the involved processes.
Results: I agree with Reviewer 1, there is a gap in the description of the macroscopic features before moving to the micro-scale. The observations and interpretations (e.g., lines 163-166; 178-183) are not adequately supported by the presented data – the reader simply has to believe in the authors’ claims. I suggest improving section 4.2, by providing a more thorough description, quantitatively supported by e.g., stereoplots or density contours of the joints and fractures. A more detailed description of the spatial setting of the 2 study areas is required, possibly including a detailed geological map.
In section 4.3 and Figure 4, a few examples of thin section microphotographs are provided; however, it is not clear from which of the 2 study sites they are sampled. No samples outside the landslide areas are shown – this fact prevents the possibility of evaluating the robustness of the authors’ interpretation. Indeed, if the rock properties in the suture zone within and outside the mapped landslides are similar, the proposed framework would not be supported.
Discussion: the interpretations described in the discussion section are reasonable, however the authors should explicitly mention which aspects of the study region are expected elsewhere and which other aspects are specific of the Jinsha River suture zone. Is the theoretical framework expected to be applicable on a global scale? Only where disrupted tectonic mélange is present? Only where high uplift rates dominate the landforms? Only where river incision is prominent?
Line-by-line comments
Lines 25-27. The last sentence of the abstract is quite ambitious. I suggest rephrasing, to be more consistent with the achieved results and implications.
Lines 38-39. Provide an explicit definition of plate suture zone. Do they represent merely the geographic boundary between different tectonic provinces? Does the definition include a seismotectonic perspective, or a lithological one? How are the boundaries defined with respect to external zones?
Lines 94-96 and figure 1b. Is the seismicity represented in Figure 1b the instrumental catalogue or the historical catalogue? Which is the time interval covered by the catalogue? Moreover, seismicity in figure 1b seems highly clustered: which are the implications of such an observation, e.g., in terms of rock properties or weakening of hillslopes?
Section 3.1. Since you aim at providing a theoretical framework of wide applicability, some extra information on the used dataset is required. Which was the methodology used to identify landslides? Is the inventory assumed to be complete over the study area? Are the landslides active? If yes, which is the rate of movement? How was slope gradient calculated – it is the average value of pixels falling within landslide polygons? Which is the resolution of the DEM used to compute the slope?
Line 129. Figures should be numbered in consequential order. It seems you introduce here Fig 3 before introducing Fig 2 at line 142.
Figure 2c-e. I don’t get the meaning of the dots in the pdf curves. I understand they are the individual landslides, but why are they shifted along the x-axis? Is it the distance from the Jinsha river?
Figure 6 panel d: please correct two typos in melting and weathering
Lines 381-382. I definitely agree with this statement; please revise the abstract, the last part of the conclusions and other places where you claim to propose a novel theoretical framework, to be more aligned with the actual content and results of the paper.
Citation: https://doi.org/10.5194/egusphere-2026-3016-RC2 -
AC2: 'Reply on RC2', Ming Wang, 20 Oct 2026
We sincerely thank the reviewer for the comprehensive and constructive evaluation of our manuscript. We appreciate the recognition of the relevance of this topic and fully acknowledge the concerns regarding the strength of the supporting evidence, the definition of plate suture zones, the representativeness of the investigated rockslides, and the applicability of the proposed conceptual model.
We agree that some statements in the original manuscript were broader than warranted by the available evidence. In particular, the expression “new theoretical framework” may imply a level of generality and validation that cannot be established from the present case study. We will therefore refine the scope of our interpretations, strengthen the presentation of the existing geological observations and analytical methods, and explicitly acknowledge the limitations of the study.
Our intended contribution is to explore how inherited lithological and structural heterogeneity within the Jinsha River suture zone may influence the preparation and localization of large rockslides, rather than to establish a universally applicable model of rockslide evolution. The main issues raised by the reviewer will be addressed as follows.
1. Scope, novelty and applicability of the conceptual model
We appreciate the reviewer’s concern that the conclusions and the proposed theoretical framework may be overly ambitious given the evidence presented. We agree that the original wording did not adequately distinguish between observations derived from the Jinsha River case study and broader geological implications.
We will replace expressions such as “new theoretical framework” and “complete dynamic sequence” with more appropriately qualified terms, including “conceptual model” and “case-based mechanistic interpretation”, throughout the manuscript. We will also revise the Abstract, the concluding paragraph of the Introduction, the Discussion, and the Conclusions to ensure that the stated contributions are proportionate to the evidence.
The proposed model is intended to highlight the potential role of geological inheritance, particularly tectonic mélanges, lithological heterogeneity, and pre-existing discontinuities, in creating geological conditions favorable for large rockslide development. Processes such as unloading, fracture propagation, weathering, freeze–thaw cycling, and gravity-driven deformation are not unique to suture zones. Rather, these processes may interact with inherited geological structures in different tectonic and geomorphic settings.
The contribution of the model therefore lies in organizing the observed relationships between inherited geological conditions and subsequent slope evolution into a case-based conceptual interpretation. Its applicability to other suture zones or mountain belts remains to be tested using independent geological observations and comparative datasets.
2. Definition and spatial extent of plate suture zones
We appreciate the reviewer’s suggestion that the geological meaning and spatial extent of plate suture zones should be more explicitly defined. We agree that this is necessary for understanding the geological setting to which our interpretation refers.
We will introduce a concise explanation when the term “plate suture zone” first appears in the Introduction and provide a more explicit geological description in Section 2.1. Plate suture zones are tectonically deformed belts formed during the closure of ocean basins and the subsequent collision and amalgamation of previously separated plates or crustal blocks. They commonly preserve complex lithological and structural assemblages, including ophiolitic remnants, tectonic mélanges, metamorphic rocks, and major fault or shear zones.
We will also clarify in Section 2.2 how the spatial extent of the Jinsha River suture zone was established, drawing on published regional tectonic and tectonostratigraphic studies. The geological units and structural boundaries represented in Figure 1 will be more clearly distinguished from the distribution of modern seismicity. In this context, the suture zone is treated as a geological and tectonic assemblage rather than merely a geographic boundary between tectonic provinces or a zone defined by present-day seismic activity.
3. Macroscopic structural evidence and geological setting of the two rockslides
We agree with the reviewer and Reviewer #1 that the original manuscript did not establish a sufficiently clear link between regional tectonic inheritance, macroscopic structural observations, and microscopic deformation features. We acknowledge that some interpretations in Section 4.2 were stated more strongly than the presented observations could independently support.
Our field investigations documented faults, foliations, joints, lithological contacts, and tensile fractures associated with the investigated rockslides. However, the original presentation did not adequately explain the orientations and spatial relationships of these structures or distinguish direct field observations from interpretations of their possible tectonic origin and contribution to slope instability.
We will strengthen Section 4.2 by presenting the available representative structural measurements more explicitly and by clarifying the relationships between discontinuities, lithological contacts, and observed or inferred sliding surfaces. We will also improve the explanation of the geological and spatial setting of the Sela and Zhisi Mountain rockslides using the available maps and field observations.
In the revised manuscript, we will strengthen Section 4.2 by reorganizing and highlighting these field-based structural observations, including the measured attitudes of representative discontinuities and their spatial relationships with lithological contacts and potential sliding surfaces. We will also clarify that these observations provide geological constraints on the preferential localization of sliding surfaces, while acknowledging that a more systematic quantitative structural inventory would further improve such interpretation.
In addition, we will acknowledge that gravitational deformation, including toppling and associated secondary shear-zone development, may modify inherited discontinuities during slope evolution. The presence of a discontinuity alone does not establish its tectonic origin or its role in sliding-surface development.
4. Thin-section sampling and limitations of the microstructural interpretation
We appreciate the reviewer’s important comments regarding the provenance and representativeness of the thin-section samples presented in Section 4.3 and Figure 4. We acknowledge that the original manuscript did not clearly identify the sampling location, making it difficult for readers to evaluate the relationship between the microstructural observations and the two investigated rockslides.
The thin-section samples presented in Figure 4 were collected from bedrock within the Sela rockslide body. We will explicitly state this information in Section 3.3, Section 4.3, and the Figure 4 caption, and clarify that these observations should not be interpreted as representing independent microstructural investigations of both the Sela and Zhisi Mountain rockslides.
We agree that comparisons between landslide and non-landslide areas would provide an important independent test of whether the observed microstructural features are preferentially associated with unstable slopes. Because systematic control sampling outside the investigated landslide was not conducted, the present thin-section dataset cannot establish that these features are absent or less developed in non-landslide areas. Nor can it independently determine whether all observed fractures and deformation features predate slope instability.
We will therefore refine the interpretation in Section 4.3. The microstructural observations will be presented as evidence of the relationships among mineral composition, foliation, and fracture development within the sampled Sela rockslide bedrock, rather than as proof that these features are unique to landslide areas or sufficient to explain the regional concentration of rockslides. We will explicitly acknowledge the lack of independent control samples and the associated uncertainty in establishing the temporal and causal relationships between rock-mass weakening and landslide development.
5. Landslide inventory, activity status and slope-gradient data
Thank you for this thoughtful comment. We agree that the identification methods, coverage, and limitations of the dataset need to be explained more clearly, particularly in relation to the intended applicability of our interpretation. We apologize that these details were insufficiently described in the original manuscript.
The landslide dataset was compiled from previously published studies, including Liu et al. (2021), Li (2023), and Zhou et al. (2024). In these source studies, landslides and potential landslides were identified through remote-sensing interpretation and geological investigations. Specifically, Zhou et al. (2024) combined remote-sensing interpretation with geological surveys, while Liu et al. (2021) used multisource optical satellite and UAV imagery, with interpretation criteria established through field verification. These criteria included image tone, landform morphology, cracks, scarps, and other deformation features. We will clarify the distinction between the identification work undertaken in the original studies and our compilation of their published records.
Regarding completeness, the source studies primarily concern large landslides and actual or potential river-blocking hazards. The resulting dataset should therefore be regarded as a compilation of documented sites rather than an exhaustive regional inventory. We acknowledge that this selective coverage may influence the observed spatial patterns and limits their generalization.
Regarding activity, the source records include both landslides that have already undergone failure and potential landslides displaying local deformation. They do not provide a consistent assessment of present-day activity across the entire dataset. Although Zhou et al. (2024) reported stability classes, these cannot be directly equated with activity states or displacement rates. Systematic and comparable movement-rate measurements are not available for the compiled dataset, and we therefore cannot reliably characterize all sites as currently active or assign a movement rate to each site. We will state this limitation explicitly.
Regarding slope gradient and DEM resolution, we appreciate the reviewer drawing attention to an important gap in our description. The slope values presented in our manuscript were taken from Li (2023), rather than calculated independently in this study. Li (2023) describes obtaining the relevant parameters through visual interpretation and ArcGIS-based analysis and reports the variable as the slope gradient of the landslide bank. However, our examination of the source has not established whether these values represent averages of slope-raster pixels within landslide polygons, nor has it identified the DEM product or resolution used to obtain them.
We recognize that using published values does not remove the need to explain their derivation and limitations. We should have made this uncertainty clear when presenting the slope data. We regret that the available information does not allow us to provide a verified answer to these two methodological questions. In the revision, we will identify the slope values explicitly as literature-derived data, disclose the unavailable methodological details, and qualify their interpretation accordingly. In particular, we will avoid using the reported slope distribution to infer a general slope threshold or to substantiate the broad applicability of the proposed interpretation.
These clarifications will be incorporated into Section 3.1 and the relevant figure captions. We will also moderate the statements concerning applicability: the compiled dataset provides regional context for our geological interpretation, but its coverage and methodological limitations mean that broader applicability requires further evaluation using independently documented datasets.
6. Representativeness of the two case studies and broader implications
We appreciate the reviewer’s concern that two detailed field sites may be insufficient to capture the variability of rockslide processes across the Jinsha River suture zone or other tectonic settings. We agree that the limited number of case studies restricts the extent to which the inferred mechanisms can be generalized.
The Jinsha River suture zone provides a useful geological setting for investigating the potential role of tectonic inheritance because it preserves complex lithological associations and inherited structures associated with its tectonic evolution, while large rockslides occur within the surrounding high-relief landscape. The regional compilation of 90 previously documented landslides provides a broader spatial context, whereas the Sela and Zhisi Mountain rockslides provide detailed field examples of possible structural and lithological controls.
Nevertheless, the regional inventory and the two field case studies serve different evidential purposes. The inventory describes the distribution and selected characteristics of documented landslides; it does not, by itself, establish the causal role of suture-zone lithology or structures. Similarly, the two field sites illustrate potential geological mechanisms but cannot represent the full variability of rockslide evolution throughout the suture zone.
We will clarify these distinctions in the Introduction and Discussion. We will further emphasize that the conceptual model is most relevant as a hypothesis for tectonically inherited mountain settings characterized by substantial lithological and structural heterogeneity. The relative importance of subsequent processes, including uplift, river incision, weathering, and freeze–thaw cycling, may differ among regions. Independent comparative studies, including investigations of non-landslide slopes and areas outside suture zones, are required to test the wider applicability of the proposed interpretation.
7. Responses to the specific line-by-line comments
7.1 Lines 25–27: Abstract
We agree that the final statement of the Abstract overstates the generality and practical implications of the study. We will replace the claim of a “new theoretical framework” with a more qualified statement emphasizing a case-based conceptual interpretation of how inherited lithological and structural heterogeneity may contribute to large rockslide development in the Jinsha River suture zone. We will also remove or appropriately qualify claims of broad engineering applicability that are not directly evaluated by the present analysis.
7.2 Lines 38–39: Definition of plate suture zones
We agree that a clear geological definition is necessary. As outlined above, we will provide an explicit description of plate suture zones in Section 2.1 and clarify the geological basis used to delineate the Jinsha River suture zone in Section 2.2. We will distinguish geological boundaries from the present-day distribution of seismicity and identify the published geological sources underlying the spatial representation of the suture zone.
7.3 Lines 94–96 and Figure 1b: Seismicity catalogue
Thank you for this helpful comment. We agree that the original manuscript did not sufficiently explain the source and temporal coverage of the seismicity data or the implications of the observed clustering, and we apologize for this omission.
The seismicity data shown in Figure 1b were obtained from the earthquake event catalogue of the International Seismological Centre (ISC; https://www.isc.ac.uk/), covering all recorded earthquake events in the Tibetan Plateau region from 31 August 1906 to 14 June 2023. The original data file was exported on 18 August 2025. We will explicitly specify the data source and the temporal coverage of the catalogue in the main text and figure caption.
The observed clustering of earthquakes may be associated with the concentration of seismic activity along active fault systems and the occurrence of mainshock–aftershock sequences. We agree that the spatial clustering of earthquake epicentres alone cannot directly demonstrate a reduction in rock-mass strength or quantify the degree of hillslope weakening. Nevertheless, this pattern highlights the potential role of repeated seismic loading. Under sufficiently strong ground shaking, successive earthquakes may promote fracture propagation and displacement along pre-existing discontinuities, leading to the progressive accumulation of rock-mass damage and potentially predisposing slopes to subsequent failure. We therefore consider cumulative seismic damage a possible contributing process rather than an established mechanism responsible for the failure of the investigated rockslides.
We will revise Lines 94–96 and the caption of Figure 1b to clarify the seismicity data and provide a more cautious discussion of the potential implications of earthquake clustering. We will also explicitly distinguish the regional seismic setting from evidence demonstrating specific seismic triggering of the investigated rockslides or a quantitative reduction in rock-mass strength.
7.4 Line 129: Figure numbering
Thank you for identifying the incorrect sequence of figure citations. We will correct the order of figure references so that the figures are introduced sequentially and consistently throughout the manuscript.
7.5 Figure 2c–e: Meaning and displacement of data points
Thank you for pointing out this lack of clarity. We agree that the original manuscript did not sufficiently explain the relationship between the individual data points and the probability density distributions.
As the reviewer correctly understood, each solid dot in Fig. 2c–e represents an individual landslide. The vertical position of each dot indicates the slope gradient in Fig. 2c, the landslide volume in Fig. 2d, and the river-channel width at the landslide location in Fig. 2e. The horizontal axis is used to distinguish among landslides located on the left bank, right bank, and tributaries. Within each group, the dots are horizontally jittered to prevent overlapping among observations with similar values. For example, two landslides with similar slope gradients may appear at approximately the same vertical position but at different horizontal positions. This horizontal displacement is solely for visual clarity; it does not represent the distance from a landslide to the Jinsha River or any other measured variable. The colored half-violin shapes summarize the estimated probability density distributions of the values within each group: a wider shape at a given vertical position indicates a higher estimated probability density near the corresponding value on the vertical axis. The dots show individual observations, whereas the colored shapes summarize their distributions; the horizontal positions of individual dots do not themselves represent probability density. In addition, Fig. 2e shows the river-channel width at each landslide location, rather than the distance between the landslide and the river.
We will revise the figure caption to include these explanations and more clearly distinguish the categorical grouping, measured values, and horizontal jitter introduced for visualization purposes.
7.6 Figure 6d: Typographical errors
Thank you for identifying these typographical errors. We will correct the spelling of “melting” and “weathering” in Figure 6d and carefully check the remaining figure labels for similar errors.
7.7 Lines 381–382: Consistency between limitations and conclusions
We appreciate the reviewer’s agreement with the limitations acknowledged in the manuscript. We agree that these limitations should be consistently reflected in the Abstract, Discussion, and Conclusions rather than being contradicted by broader claims elsewhere.
We will therefore revise statements implying that the study establishes a novel and generally applicable theoretical framework. Instead, we will present the proposed model as a case-based interpretation of the potential interactions among tectonic inheritance, lithological and structural heterogeneity, and subsequent slope evolution. We will also explicitly state that its applicability beyond the Jinsha River suture zone requires further investigation and independent validation.
We sincerely thank the reviewer for the detailed and constructive comments. We recognize that the most important improvements required concern not only the wording of the manuscript, but also the transparency of the underlying data, the distinction between observation and interpretation, and the degree to which the proposed mechanisms are supported by the available evidence.
We will address these issues in the revised manuscript and ensure that the scope of the conclusions is consistent with the regional landslide compilation, the two investigated field sites, and the microstructural observations available for the Sela rockslide. We believe that these revisions will provide a clearer and more appropriately constrained assessment of the potential role of suture-zone geological inheritance in large rockslide development.
Citation: https://doi.org/10.5194/egusphere-2026-3016-AC2
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AC2: 'Reply on RC2', Ming Wang, 20 Oct 2026
Status: closed
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RC1: 'Comment on egusphere-2026-3016', Anonymous Referee #1, 07 Aug 2026
Dear authors,
the subject you have been working on, i.e. rockslides in suture zones is certainly of great interest.
However, within your approach there is a clear gap : the analysis of macro-structures before investigating micro-structures.
You jump immediately from regional tectonics to thin section scale .. via a few views of outcrops. But, no results of macroscopic
structural geology shown (stereoplots etc).
Then, you present Fig 6 as a schematic representation of your results - outlining apparently special characteristics of rockslides
in suture zones .. while you could present precisely the same rockslide evolution schemes for major mass movements in the European
Alps, very far away from any suture zones. The missing point .. as you have not analysed macro-structures, those features you show in Fig 6
are most of the times related to toppling, .. which can also locally create shear zones after creep (not related to regional tectonics).
So, for me, without a deep macro-structural analysis you are too much generalising your results, to cover examples that have nothing
to do with suture zones.
yours
reviewer H
Citation: https://doi.org/10.5194/egusphere-2026-3016-RC1 -
AC1: 'Reply on RC1', Ming Wang, 20 Oct 2026
Thank you very much for this insightful and constructive comment. We appreciate the reviewer’s careful evaluation of the relationship between regional tectonic inheritance, slope-scale deformation, and large rockslide development. We agree that understanding how inherited geological structures influence slope instability requires consideration of geological structures across multiple scales, from regional tectonic settings to slope-scale discontinuities.
Regarding the concern about the lack of macroscopic structural analysis, we appreciate this important suggestion. We acknowledge that the original manuscript did not sufficiently emphasize the connection between field-based structural observations and the localization of potential sliding surfaces. In fact, our field investigations have documented various macroscopic structural features, including faults, foliations, joints, lithological contacts, and tension cracks. However, their role in linking regional tectonic inheritance with slope-scale deformation was not adequately highlighted in the original manuscript.
In the revised manuscript, we will strengthen Section 4.2 by incorporating and further interpreting these field-based structural observations, including representative discontinuity orientations and their spatial relationships with lithological contacts and potential sliding surfaces. These revisions will better establish the linkage between regional structural inheritance, slope-scale deformation, and microscale weakening processes. We will also clarify that these observations provide geological constraints on the preferential localization of sliding surfaces, while acknowledging that a more systematic quantitative structural inventory would further improve the understanding of structural controls on large rockslide development.
We also appreciate the reviewer’s comment regarding the interpretation and scope of the conceptual model presented in Fig. 6. We agree that processes such as unloading, weathering, fracture propagation, and slope deformation are not unique to suture zones and may also occur in other high-relief mountain belts. The key implication of our study is not that these deformation processes represent exclusive characteristics of suture zones, but rather that suture zones commonly preserve a favorable geological environment characterized by tectonic mélanges, heterogeneous lithologies, and inherited discontinuities, which may influence the preparation and localization of large rockslides.
To avoid overgeneralization and better clarify the scope of our conceptual model, we will revise the description of Fig. 6 and the related discussion in Section 5.2. Specifically, we will modify the title of Fig. 6 from “Schematic diagram of the preparation and evolution model of rockslides in suture zones” to “Conceptual model illustrating the role of suture-zone geological inheritance in the preparation and evolution of large rockslides”. We will also revise the description of the four-stage conceptual model to emphasize the role of suture-zone geological inheritance rather than representing an exclusive evolution pathway of rockslides in suture zones.
Regarding the possible role of toppling proposed by the reviewer, we appreciate this important consideration. We acknowledge that gravity-driven deformation, including toppling, may generate secondary shear zones during long-term slope evolution. However, our study does not intend to attribute all observed deformation structures exclusively to regional tectonic processes. Instead, we focus on evaluating how inherited geological structures may influence the preferential localization of potential sliding surfaces. We will clarify this point in the revised manuscript and acknowledge that gravity-driven deformation may interact with inherited geological structures during slope evolution.
These revisions will improve the balance between the geological evidence presented and the scope of our interpretation, and will help clarify the respective roles of inherited geological structures and subsequent slope-evolution processes in large rockslide development. We sincerely appreciate this comment, which has helped us refine the interpretation and improve the clarity of the conceptual model.
Citation: https://doi.org/10.5194/egusphere-2026-3016-AC1
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AC1: 'Reply on RC1', Ming Wang, 20 Oct 2026
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RC2: 'Comment on egusphere-2026-3016', Anonymous Referee #2, 14 Sep 2026
The paper by Zhou et al investigates two large rockslides in the Jinsha River area through field surveys and thin section analyses, to decipher the factors controlling landslide occurrence, ultimately proposing a theoretical framework. The topic is certainly of interest to the journal audience, however I think the paper requires major revisions to meet the criteria for publication.
The conclusions are ambitious and far-reaching, but the data presented here do not fully support such claims. An explicit definition of suture zones is lacking; by definition, tectonic melanges are highly heterogeneous, so a proper definition of the type of settings that can be analyzed using the proposed framework is relevant.
I think some rephrasing and providing more nuanced statements (e.g., last part of the abstract) could better reflect the paper contents. Indeed, the authors present their work as a new theoretical framework. If this is the case, the authors should better explain which is the novel content of the proposed framework and why the Jinsha river area is a reliable place to develop such framework. Moreover, their interpretations are based on 2 field sites only, which may be not enough to grasp the variability of the involved processes.
Results: I agree with Reviewer 1, there is a gap in the description of the macroscopic features before moving to the micro-scale. The observations and interpretations (e.g., lines 163-166; 178-183) are not adequately supported by the presented data – the reader simply has to believe in the authors’ claims. I suggest improving section 4.2, by providing a more thorough description, quantitatively supported by e.g., stereoplots or density contours of the joints and fractures. A more detailed description of the spatial setting of the 2 study areas is required, possibly including a detailed geological map.
In section 4.3 and Figure 4, a few examples of thin section microphotographs are provided; however, it is not clear from which of the 2 study sites they are sampled. No samples outside the landslide areas are shown – this fact prevents the possibility of evaluating the robustness of the authors’ interpretation. Indeed, if the rock properties in the suture zone within and outside the mapped landslides are similar, the proposed framework would not be supported.
Discussion: the interpretations described in the discussion section are reasonable, however the authors should explicitly mention which aspects of the study region are expected elsewhere and which other aspects are specific of the Jinsha River suture zone. Is the theoretical framework expected to be applicable on a global scale? Only where disrupted tectonic mélange is present? Only where high uplift rates dominate the landforms? Only where river incision is prominent?
Line-by-line comments
Lines 25-27. The last sentence of the abstract is quite ambitious. I suggest rephrasing, to be more consistent with the achieved results and implications.
Lines 38-39. Provide an explicit definition of plate suture zone. Do they represent merely the geographic boundary between different tectonic provinces? Does the definition include a seismotectonic perspective, or a lithological one? How are the boundaries defined with respect to external zones?
Lines 94-96 and figure 1b. Is the seismicity represented in Figure 1b the instrumental catalogue or the historical catalogue? Which is the time interval covered by the catalogue? Moreover, seismicity in figure 1b seems highly clustered: which are the implications of such an observation, e.g., in terms of rock properties or weakening of hillslopes?
Section 3.1. Since you aim at providing a theoretical framework of wide applicability, some extra information on the used dataset is required. Which was the methodology used to identify landslides? Is the inventory assumed to be complete over the study area? Are the landslides active? If yes, which is the rate of movement? How was slope gradient calculated – it is the average value of pixels falling within landslide polygons? Which is the resolution of the DEM used to compute the slope?
Line 129. Figures should be numbered in consequential order. It seems you introduce here Fig 3 before introducing Fig 2 at line 142.
Figure 2c-e. I don’t get the meaning of the dots in the pdf curves. I understand they are the individual landslides, but why are they shifted along the x-axis? Is it the distance from the Jinsha river?
Figure 6 panel d: please correct two typos in melting and weathering
Lines 381-382. I definitely agree with this statement; please revise the abstract, the last part of the conclusions and other places where you claim to propose a novel theoretical framework, to be more aligned with the actual content and results of the paper.
Citation: https://doi.org/10.5194/egusphere-2026-3016-RC2 -
AC2: 'Reply on RC2', Ming Wang, 20 Oct 2026
We sincerely thank the reviewer for the comprehensive and constructive evaluation of our manuscript. We appreciate the recognition of the relevance of this topic and fully acknowledge the concerns regarding the strength of the supporting evidence, the definition of plate suture zones, the representativeness of the investigated rockslides, and the applicability of the proposed conceptual model.
We agree that some statements in the original manuscript were broader than warranted by the available evidence. In particular, the expression “new theoretical framework” may imply a level of generality and validation that cannot be established from the present case study. We will therefore refine the scope of our interpretations, strengthen the presentation of the existing geological observations and analytical methods, and explicitly acknowledge the limitations of the study.
Our intended contribution is to explore how inherited lithological and structural heterogeneity within the Jinsha River suture zone may influence the preparation and localization of large rockslides, rather than to establish a universally applicable model of rockslide evolution. The main issues raised by the reviewer will be addressed as follows.
1. Scope, novelty and applicability of the conceptual model
We appreciate the reviewer’s concern that the conclusions and the proposed theoretical framework may be overly ambitious given the evidence presented. We agree that the original wording did not adequately distinguish between observations derived from the Jinsha River case study and broader geological implications.
We will replace expressions such as “new theoretical framework” and “complete dynamic sequence” with more appropriately qualified terms, including “conceptual model” and “case-based mechanistic interpretation”, throughout the manuscript. We will also revise the Abstract, the concluding paragraph of the Introduction, the Discussion, and the Conclusions to ensure that the stated contributions are proportionate to the evidence.
The proposed model is intended to highlight the potential role of geological inheritance, particularly tectonic mélanges, lithological heterogeneity, and pre-existing discontinuities, in creating geological conditions favorable for large rockslide development. Processes such as unloading, fracture propagation, weathering, freeze–thaw cycling, and gravity-driven deformation are not unique to suture zones. Rather, these processes may interact with inherited geological structures in different tectonic and geomorphic settings.
The contribution of the model therefore lies in organizing the observed relationships between inherited geological conditions and subsequent slope evolution into a case-based conceptual interpretation. Its applicability to other suture zones or mountain belts remains to be tested using independent geological observations and comparative datasets.
2. Definition and spatial extent of plate suture zones
We appreciate the reviewer’s suggestion that the geological meaning and spatial extent of plate suture zones should be more explicitly defined. We agree that this is necessary for understanding the geological setting to which our interpretation refers.
We will introduce a concise explanation when the term “plate suture zone” first appears in the Introduction and provide a more explicit geological description in Section 2.1. Plate suture zones are tectonically deformed belts formed during the closure of ocean basins and the subsequent collision and amalgamation of previously separated plates or crustal blocks. They commonly preserve complex lithological and structural assemblages, including ophiolitic remnants, tectonic mélanges, metamorphic rocks, and major fault or shear zones.
We will also clarify in Section 2.2 how the spatial extent of the Jinsha River suture zone was established, drawing on published regional tectonic and tectonostratigraphic studies. The geological units and structural boundaries represented in Figure 1 will be more clearly distinguished from the distribution of modern seismicity. In this context, the suture zone is treated as a geological and tectonic assemblage rather than merely a geographic boundary between tectonic provinces or a zone defined by present-day seismic activity.
3. Macroscopic structural evidence and geological setting of the two rockslides
We agree with the reviewer and Reviewer #1 that the original manuscript did not establish a sufficiently clear link between regional tectonic inheritance, macroscopic structural observations, and microscopic deformation features. We acknowledge that some interpretations in Section 4.2 were stated more strongly than the presented observations could independently support.
Our field investigations documented faults, foliations, joints, lithological contacts, and tensile fractures associated with the investigated rockslides. However, the original presentation did not adequately explain the orientations and spatial relationships of these structures or distinguish direct field observations from interpretations of their possible tectonic origin and contribution to slope instability.
We will strengthen Section 4.2 by presenting the available representative structural measurements more explicitly and by clarifying the relationships between discontinuities, lithological contacts, and observed or inferred sliding surfaces. We will also improve the explanation of the geological and spatial setting of the Sela and Zhisi Mountain rockslides using the available maps and field observations.
In the revised manuscript, we will strengthen Section 4.2 by reorganizing and highlighting these field-based structural observations, including the measured attitudes of representative discontinuities and their spatial relationships with lithological contacts and potential sliding surfaces. We will also clarify that these observations provide geological constraints on the preferential localization of sliding surfaces, while acknowledging that a more systematic quantitative structural inventory would further improve such interpretation.
In addition, we will acknowledge that gravitational deformation, including toppling and associated secondary shear-zone development, may modify inherited discontinuities during slope evolution. The presence of a discontinuity alone does not establish its tectonic origin or its role in sliding-surface development.
4. Thin-section sampling and limitations of the microstructural interpretation
We appreciate the reviewer’s important comments regarding the provenance and representativeness of the thin-section samples presented in Section 4.3 and Figure 4. We acknowledge that the original manuscript did not clearly identify the sampling location, making it difficult for readers to evaluate the relationship between the microstructural observations and the two investigated rockslides.
The thin-section samples presented in Figure 4 were collected from bedrock within the Sela rockslide body. We will explicitly state this information in Section 3.3, Section 4.3, and the Figure 4 caption, and clarify that these observations should not be interpreted as representing independent microstructural investigations of both the Sela and Zhisi Mountain rockslides.
We agree that comparisons between landslide and non-landslide areas would provide an important independent test of whether the observed microstructural features are preferentially associated with unstable slopes. Because systematic control sampling outside the investigated landslide was not conducted, the present thin-section dataset cannot establish that these features are absent or less developed in non-landslide areas. Nor can it independently determine whether all observed fractures and deformation features predate slope instability.
We will therefore refine the interpretation in Section 4.3. The microstructural observations will be presented as evidence of the relationships among mineral composition, foliation, and fracture development within the sampled Sela rockslide bedrock, rather than as proof that these features are unique to landslide areas or sufficient to explain the regional concentration of rockslides. We will explicitly acknowledge the lack of independent control samples and the associated uncertainty in establishing the temporal and causal relationships between rock-mass weakening and landslide development.
5. Landslide inventory, activity status and slope-gradient data
Thank you for this thoughtful comment. We agree that the identification methods, coverage, and limitations of the dataset need to be explained more clearly, particularly in relation to the intended applicability of our interpretation. We apologize that these details were insufficiently described in the original manuscript.
The landslide dataset was compiled from previously published studies, including Liu et al. (2021), Li (2023), and Zhou et al. (2024). In these source studies, landslides and potential landslides were identified through remote-sensing interpretation and geological investigations. Specifically, Zhou et al. (2024) combined remote-sensing interpretation with geological surveys, while Liu et al. (2021) used multisource optical satellite and UAV imagery, with interpretation criteria established through field verification. These criteria included image tone, landform morphology, cracks, scarps, and other deformation features. We will clarify the distinction between the identification work undertaken in the original studies and our compilation of their published records.
Regarding completeness, the source studies primarily concern large landslides and actual or potential river-blocking hazards. The resulting dataset should therefore be regarded as a compilation of documented sites rather than an exhaustive regional inventory. We acknowledge that this selective coverage may influence the observed spatial patterns and limits their generalization.
Regarding activity, the source records include both landslides that have already undergone failure and potential landslides displaying local deformation. They do not provide a consistent assessment of present-day activity across the entire dataset. Although Zhou et al. (2024) reported stability classes, these cannot be directly equated with activity states or displacement rates. Systematic and comparable movement-rate measurements are not available for the compiled dataset, and we therefore cannot reliably characterize all sites as currently active or assign a movement rate to each site. We will state this limitation explicitly.
Regarding slope gradient and DEM resolution, we appreciate the reviewer drawing attention to an important gap in our description. The slope values presented in our manuscript were taken from Li (2023), rather than calculated independently in this study. Li (2023) describes obtaining the relevant parameters through visual interpretation and ArcGIS-based analysis and reports the variable as the slope gradient of the landslide bank. However, our examination of the source has not established whether these values represent averages of slope-raster pixels within landslide polygons, nor has it identified the DEM product or resolution used to obtain them.
We recognize that using published values does not remove the need to explain their derivation and limitations. We should have made this uncertainty clear when presenting the slope data. We regret that the available information does not allow us to provide a verified answer to these two methodological questions. In the revision, we will identify the slope values explicitly as literature-derived data, disclose the unavailable methodological details, and qualify their interpretation accordingly. In particular, we will avoid using the reported slope distribution to infer a general slope threshold or to substantiate the broad applicability of the proposed interpretation.
These clarifications will be incorporated into Section 3.1 and the relevant figure captions. We will also moderate the statements concerning applicability: the compiled dataset provides regional context for our geological interpretation, but its coverage and methodological limitations mean that broader applicability requires further evaluation using independently documented datasets.
6. Representativeness of the two case studies and broader implications
We appreciate the reviewer’s concern that two detailed field sites may be insufficient to capture the variability of rockslide processes across the Jinsha River suture zone or other tectonic settings. We agree that the limited number of case studies restricts the extent to which the inferred mechanisms can be generalized.
The Jinsha River suture zone provides a useful geological setting for investigating the potential role of tectonic inheritance because it preserves complex lithological associations and inherited structures associated with its tectonic evolution, while large rockslides occur within the surrounding high-relief landscape. The regional compilation of 90 previously documented landslides provides a broader spatial context, whereas the Sela and Zhisi Mountain rockslides provide detailed field examples of possible structural and lithological controls.
Nevertheless, the regional inventory and the two field case studies serve different evidential purposes. The inventory describes the distribution and selected characteristics of documented landslides; it does not, by itself, establish the causal role of suture-zone lithology or structures. Similarly, the two field sites illustrate potential geological mechanisms but cannot represent the full variability of rockslide evolution throughout the suture zone.
We will clarify these distinctions in the Introduction and Discussion. We will further emphasize that the conceptual model is most relevant as a hypothesis for tectonically inherited mountain settings characterized by substantial lithological and structural heterogeneity. The relative importance of subsequent processes, including uplift, river incision, weathering, and freeze–thaw cycling, may differ among regions. Independent comparative studies, including investigations of non-landslide slopes and areas outside suture zones, are required to test the wider applicability of the proposed interpretation.
7. Responses to the specific line-by-line comments
7.1 Lines 25–27: Abstract
We agree that the final statement of the Abstract overstates the generality and practical implications of the study. We will replace the claim of a “new theoretical framework” with a more qualified statement emphasizing a case-based conceptual interpretation of how inherited lithological and structural heterogeneity may contribute to large rockslide development in the Jinsha River suture zone. We will also remove or appropriately qualify claims of broad engineering applicability that are not directly evaluated by the present analysis.
7.2 Lines 38–39: Definition of plate suture zones
We agree that a clear geological definition is necessary. As outlined above, we will provide an explicit description of plate suture zones in Section 2.1 and clarify the geological basis used to delineate the Jinsha River suture zone in Section 2.2. We will distinguish geological boundaries from the present-day distribution of seismicity and identify the published geological sources underlying the spatial representation of the suture zone.
7.3 Lines 94–96 and Figure 1b: Seismicity catalogue
Thank you for this helpful comment. We agree that the original manuscript did not sufficiently explain the source and temporal coverage of the seismicity data or the implications of the observed clustering, and we apologize for this omission.
The seismicity data shown in Figure 1b were obtained from the earthquake event catalogue of the International Seismological Centre (ISC; https://www.isc.ac.uk/), covering all recorded earthquake events in the Tibetan Plateau region from 31 August 1906 to 14 June 2023. The original data file was exported on 18 August 2025. We will explicitly specify the data source and the temporal coverage of the catalogue in the main text and figure caption.
The observed clustering of earthquakes may be associated with the concentration of seismic activity along active fault systems and the occurrence of mainshock–aftershock sequences. We agree that the spatial clustering of earthquake epicentres alone cannot directly demonstrate a reduction in rock-mass strength or quantify the degree of hillslope weakening. Nevertheless, this pattern highlights the potential role of repeated seismic loading. Under sufficiently strong ground shaking, successive earthquakes may promote fracture propagation and displacement along pre-existing discontinuities, leading to the progressive accumulation of rock-mass damage and potentially predisposing slopes to subsequent failure. We therefore consider cumulative seismic damage a possible contributing process rather than an established mechanism responsible for the failure of the investigated rockslides.
We will revise Lines 94–96 and the caption of Figure 1b to clarify the seismicity data and provide a more cautious discussion of the potential implications of earthquake clustering. We will also explicitly distinguish the regional seismic setting from evidence demonstrating specific seismic triggering of the investigated rockslides or a quantitative reduction in rock-mass strength.
7.4 Line 129: Figure numbering
Thank you for identifying the incorrect sequence of figure citations. We will correct the order of figure references so that the figures are introduced sequentially and consistently throughout the manuscript.
7.5 Figure 2c–e: Meaning and displacement of data points
Thank you for pointing out this lack of clarity. We agree that the original manuscript did not sufficiently explain the relationship between the individual data points and the probability density distributions.
As the reviewer correctly understood, each solid dot in Fig. 2c–e represents an individual landslide. The vertical position of each dot indicates the slope gradient in Fig. 2c, the landslide volume in Fig. 2d, and the river-channel width at the landslide location in Fig. 2e. The horizontal axis is used to distinguish among landslides located on the left bank, right bank, and tributaries. Within each group, the dots are horizontally jittered to prevent overlapping among observations with similar values. For example, two landslides with similar slope gradients may appear at approximately the same vertical position but at different horizontal positions. This horizontal displacement is solely for visual clarity; it does not represent the distance from a landslide to the Jinsha River or any other measured variable. The colored half-violin shapes summarize the estimated probability density distributions of the values within each group: a wider shape at a given vertical position indicates a higher estimated probability density near the corresponding value on the vertical axis. The dots show individual observations, whereas the colored shapes summarize their distributions; the horizontal positions of individual dots do not themselves represent probability density. In addition, Fig. 2e shows the river-channel width at each landslide location, rather than the distance between the landslide and the river.
We will revise the figure caption to include these explanations and more clearly distinguish the categorical grouping, measured values, and horizontal jitter introduced for visualization purposes.
7.6 Figure 6d: Typographical errors
Thank you for identifying these typographical errors. We will correct the spelling of “melting” and “weathering” in Figure 6d and carefully check the remaining figure labels for similar errors.
7.7 Lines 381–382: Consistency between limitations and conclusions
We appreciate the reviewer’s agreement with the limitations acknowledged in the manuscript. We agree that these limitations should be consistently reflected in the Abstract, Discussion, and Conclusions rather than being contradicted by broader claims elsewhere.
We will therefore revise statements implying that the study establishes a novel and generally applicable theoretical framework. Instead, we will present the proposed model as a case-based interpretation of the potential interactions among tectonic inheritance, lithological and structural heterogeneity, and subsequent slope evolution. We will also explicitly state that its applicability beyond the Jinsha River suture zone requires further investigation and independent validation.
We sincerely thank the reviewer for the detailed and constructive comments. We recognize that the most important improvements required concern not only the wording of the manuscript, but also the transparency of the underlying data, the distinction between observation and interpretation, and the degree to which the proposed mechanisms are supported by the available evidence.
We will address these issues in the revised manuscript and ensure that the scope of the conclusions is consistent with the regional landslide compilation, the two investigated field sites, and the microstructural observations available for the Sela rockslide. We believe that these revisions will provide a clearer and more appropriately constrained assessment of the potential role of suture-zone geological inheritance in large rockslide development.
Citation: https://doi.org/10.5194/egusphere-2026-3016-AC2
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AC2: 'Reply on RC2', Ming Wang, 20 Oct 2026
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Dear authors,
the subject you have been working on, i.e. rockslides in suture zones is certainly of great interest.
However, within your approach there is a clear gap : the analysis of macro-structures before investigating micro-structures.
You jump immediately from regional tectonics to thin section scale .. via a few views of outcrops. But, no results of macroscopic
structural geology shown (stereoplots etc).
Then, you present Fig 6 as a schematic representation of your results - outlining apparently special characteristics of rockslides
in suture zones .. while you could present precisely the same rockslide evolution schemes for major mass movements in the European
Alps, very far away from any suture zones. The missing point .. as you have not analysed macro-structures, those features you show in Fig 6
are most of the times related to toppling, .. which can also locally create shear zones after creep (not related to regional tectonics).
So, for me, without a deep macro-structural analysis you are too much generalising your results, to cover examples that have nothing
to do with suture zones.
yours
reviewer H