Casual-Nuevo Alausí Landslide (Ecuador, March 2023): A Case Study on the Influence of the Anthropogenic Factors

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study provides a meaningful analysis of anthropogenic factors contributing to the Alausí landslide (March 2023) in Ecuador. However, the arguments would benefit from enhanced data-driven validation (e.g., geotechnical modeling, numerical simulations) and deeper mechanistic interpretations. We recommend supplementing key quantitative evidence (e.g., fill load mechanics, seismic ground motion response, and seepage simulations) and refining policy implementation details to strengthen both scientific rigor and practical relevance.

 

1. Introduction

The literature review focuses narrowly on cases from southern Ecuador, neglecting discussions of international theoretical frameworks (e.g., coupled human-environment systems, urban expansion threshold dynamics). This limits the study’s generalizability and theoretical depth. We suggest incorporating comparisons with analogous landslides in regions like Asia or the northern Andes to clarify the novelty and broader significance of this work.

 

2. Geographical/Geological Approach

The geotechnical parameters (e.g., shear strength, hydraulic conductivity) presented in the landslide zone rely on localized tests without clarifying sampling representativeness (e.g., whether samples cover critical areas such as the landslide scarp or toe). To enhance credibility, systematic geotechnical data or regional stratigraphic reference values should be integrated into the geological model.

 

3. Anthropogenic Factors

The causal link between fill volumes (47,000–79,000 m³) and landslide magnitude (1.3 million m³) remains quantitatively unsubstantiated**. A limit equilibrium analysis (e.g., using SLIDE software) should be conducted to simulate how fill loading reduces the slope’s safety factor, thereby avoiding oversimplification in attributing the landslide’s primary trigger.

 

4. Results

The dismissal of seismic triggering effects from the Balao earthquake (Mw6.6) relies solely on macroseismic intensity (EMS-IV) rather than site-specific ground motion analysis (e.g., peak ground acceleration calculations). We recommend incorporating seismic wave propagation modeling or comparisons with coseismic landslide cases to strengthen this argument.

 

5. Conclusions

The policy recommendation for "sustainable land management" is overly generic and fails to address local governance challenges, such as Alausí’s land tenure structures (e.g., indigenous community autonomy). Practical measures—like legal mechanisms for "no-build zones" or farmer compensation frameworks—should be specified to ensure actionable outcomes.

Comments for author File: Comments.docx

Author Response

Dear review,

We have responded to your comments in the attached file.

Thank you for your comments.

Kind regards

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript needs a major revision.

• Figure 3: Please add a North indicator (north arrow) to orient the readers spatially.
• Figure 10 A & B: The purpose of including Figure 10 A & B is currently unclear.
• The manuscript refers to “intense rainfall” but does not present long‐term, high‐resolution pluviometer or radar data to quantify antecedent and event‐rainfall thresholds. Further, no continuous groundwater or pore‐pressure measurements were reported, making it impossible to link specific saturation levels to slope failure. Authors should acknowledge these limitations of the study.
• Authors mentioned seismic activity as a trigger, but there is no time‐synchronized accelerometer or macro-seismic intensity data for the event. Clarification from authors is needed.
• Why authors have not used limit‐equilibrium or finite‐element slope‐stability analyses to test anthropogenic factors alter factors of safety under varying loads. Clarification from authors is needed.
• Field investigations seem confined to post‐failure reconnaissance. There is no mention of pre‐event geotechnical boreholes, in situ shear tests, or soil‐sample laboratory tests to characterize subsurface stratigraphy and strength. Authors should acknowledge these limitations of the study.
• Alausí’s geology (e.g., volcanic ash layers, highly weathered Andesitic bedrock) and socio‐economic drivers are unique; the study does not delineate which findings are universal versus context dependent. Further, there is no cross‐case comparison with other Ecuadorian or Andean canton landslides to test whether the same anthropogenic factors played similar roles elsewhere. Authors are advised to work on it and include the comparison data in discussion section (section 5).

Author Response

Dear review,

We have responded to your comments in the attached file.

Thank you for your comments.

Kind regards

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript entitled “Casual-Nuevo Alausí landslide (Ecuador, March 2023). A case study on the influence of the anthropogenic factors” provide information about the Alausí landslide phenomena, occurred in march 2023 in Ecuador.

The study provide useful information about the predisposing factors that could have exerted a relevant role for this instability phenomena. However, compared to a very extensive descriptive part related to the geology and geographic information of the study area, the “results” section lacks a detailed susceptibility study. I suggest to apply the data-drive approach to obtain a susceptibility map for the study area.

Here a detailed list of critical points that must be modified and improved:

Title: “Casual-Nuevo Alausí landslide: A case study on the influence of the anthropogenic factors”.

Line 23: “improper”? Please use other term.

Line 26: “which could be the cause of the rupture process” i.e., landslides triggering factors

Line 37: the phrase is not clear. Please rewrite the sentence. A possible introduction related to disaster events and hazard can be found in “ Davies, 2015 Chapter 1 - Landslide Hazards, Risks, and Disasters: Introduction https://www.sciencedirect.com/science/article/pii/B978012396452600001X”

Line 41-43: please improve the description of the landslide in the context of the hazard and susceptibility evaluation. Indeed, there are two approaches able to provide support to the administrations and civil protection agencies in the mitigation of this particular risk related to landslides: hazard assessment in support of the land management and the forecasting of the temporal and spatial distribution of these events.

Line 48: triggered by?

I think it is better to move the first description of the landslide (and the related figures) from the introduction to the section 2.

Line 91: “field surveys”, not trips

Figure 3: is it possible to add event the DEM description of the same image?

Line 166: is it saprolite weathering processes? Here some references:

- Amaddii, M.; Rosatti, G.; Zugliani, D.; Marzini, L.; Disperati, L. Back-Analysis of the Abbadia San Salvatore (Mt. Amiata, Italy) Debris Flow of 27–28 July 2019: An Integrated Multidisciplinary Approach to a Challenging Case Study. Geosciences 2022, 12, 385.

-Certini, G.; Wilson, M.J.; Hillier, S.J.; Fraser, A.R.; Delbos, E. Mineral weathering in trachydacitic derived soils and saprolites involving formation of embryonic halloysite and gibbsite at Mt. Amiata, Central Italy. Geoderma 2006, 133, 173–190

-Principe, C.; Vezzoli, L. Characteristics and significance of intravolcanic saprolite paleoweathering and associate paleosurface in a silicic effusive volcano: The case study of Monte Amiata (middle Pleistocene, Tuscany, Italy). Geomorphology 2021, 392, 107922.

Line 180: “Hydrogeological”, please correct the word

Figure 5: Legend: landslide area, not affected. Is it possible to add to the spatial distribution of the rain gauges considered?

Line 268-280: susceptibility evaluation based on? Data-driven or physically-based approaches?

Line 365: pay attention to the morphometric characteristics of the landslide (basal failure plane). Indeed, below-ground vegetation (roots) plays a role towards instability phenomena in case of shallow landslides. In detail, roots do not reach the depth of the shallow landslide basal failure plane (usually located around 1–2 m). As reported in Marzini et al., (2023), considering the root density decrease with depth, roots within the mobilized landslide volume do not crucially provide significant reinforcement along the basal-failure plane. (Marzini, L.; D’Addario, E.; Papasidero, M.P.; Chianucci, F.; Disperati, L. Influence of Root Reinforcement on Shallow Landslide Distribution: A Case Study in Garfagnana (Northern Tuscany, Italy). Geosciences 2023, 13, 326. https://doi.org/10.3390/geosciences13110326)

Line 475: can you add a map with the seismic events recorded?

Line 489: for the reader it is better to add a table with the points analysed and the presence/absence of these for the study area.

Moreover, as a general comment, for this study case results must be presented in terms of susceptibility of the study area. The authors can apply a data-driven approach in which, combining the different data layers available for the study area (geology, DEM, vegetation cover, faults, hydrogeology, etc), is it possible to observe the landslide distribution with the predisposing factors distribution. Here I suggest some references that use this approach:

- Mapping landslide susceptibility using data-driven methods (J.L. Zêzere, S. Pereira, R. Melo, S.C. Oliveira, R.A.C. Garcia, 2017)

- A physics-informed data-driven model for landslide susceptibility assessment in the Three Gorges Reservoir area (Songlin Liu, Luqi Wang, Wengang Zhang, Weixin Sun, Jie Fu, Ting Xiao, Zhenwei Dai (2023))

- A Data-Driven Approach to Landslide-Susceptibility Mapping in Mountainous Terrain: Case Study from the Northwest Himalayas, Pakistan (2018)

- A data-driven approach for landslide susceptibility mapping: a case study of Shennongjia Forestry District, China. Wei Chen,Hongxing Han,Bin Huang,Qile Huang & Xudong Fu

- Comparative review of data-driven landslide susceptibility models: case study in the Eastern Andes mountain range of Colombia. (Wilmar Calderón-Guevara, Mauricio Sánchez-Silva, Bogdan Nitescu & Daniel F. Villarraga, 2022)

- Sheng, Y.; Xu, G.; Jin, B.; Zhou, C.; Li, Y.; Chen, W. Data-Driven Landslide Spatial Prediction and Deformation Monitoring: A Case Study of Shiyan City, China. Remote Sens. 2023, 15, 5256. https://doi.org/10.3390/rs15215256

Even the discussion section will improve through the comparison with other case studies.

Author Response

Dear review,

We have responded to your comments in the attached file.

Thank you for your comments.

Kind regards

Author Response File: Author Response.docx

Reviewer 4 Report

Comments and Suggestions for Authors

The paper is interesting as it investigates how human actions, such as unplanned city growth, poor drainage, deforestation, and inadequate road construction, contributed to increasing the area's vulnerability. However, this assessment is based almost exclusively on qualitative and descriptive criteria. While such an approach can still provide valuable insights, it remains less robust than analyses supported by quantitative data or direct evidence.

The paper suggests that better urban planning, combined with geological and hydrological studies, could prevent disasters like the landslide event in Alausí.

However, the manuscript requires significant editing to modify sentence structures and correct grammatical errors.

Unfortunately, the manuscript contains numerous similar cases that hinder clarity and readability. Therefore, I strongly recommend significant language editing.

The figures presented in the manuscript are of high quality, clearly formatted, and effectively support the paper's content.

Line 215. Do you mean 5 to 10 times?

Line 336 (and others). Do you mean March?

Figure 8. It seems that this is not the exact position between subfigures A & B

Section 4.1. this should have a list format (with bullets)

Section 4.2. The correlations presented are vague and qualitative. I would recommend merging this section with section 4.1 and presenting a more robust connection between human activities and the landslide triggering factors.

Sections 5 and 6 need to discuss in more depth the mechanisms by which anthropogenic and natural factors interact and contribute to the event's triggering. Even though such an evaluation could be qualitative, it would be especially instructive if the authors could address the relative contributions of each component, whether natural or human-induced. In any event, the weighting of each parameter should be discussed in the context of the evidence that is currently available, particularly in light of the fact that strong seismic excitation occurred close to the failure site just before the event and that rainfall levels were reported to be 5–10 times higher than average before the failure.

Comments on the Quality of English Language

Τhe manuscript requires significant editing to modify sentence structures and correct grammatical errors. For example:

The first sentence of the abstract: Fatalities refers to deaths, but in this sentence, it seems to refer to landslides- a landslide is not a fatality but a cause of fatalities.

The first sentence of chapter 1: The term “hazard risk” is not standard. Please not that hazard is defined as a potentially damaging physical event, while risk is the probability of harmful consequences resulting from interactions between hazards, exposure, vulnerability, and significance.

Author Response

Dear review,

We have responded to your comments in the attached file.

Thank you for your comments.

Kind regards

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Accept in present form

Author Response

Dear review,

We have responded to your comments in the attached file.

Thank you for your comments.

Kind regards

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

Revised manuscript is in good shape and can be consider for publication.

Author Response

Dear review,

We have responded to your comments in the attached file.

Thank you for your comments.

Kind regards

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

After the first round of revision the quality of the manuscript has increased. Congratulations!

Author Response

Dear review,

We have responded to your comments in the attached file.

Thank you for your comments.

Kind regards

Author Response File: Author Response.docx

Reviewer 4 Report

Comments and Suggestions for Authors

The revised version shows clear improvement, especially in terms of the English language, and the effort made is appreciated. The topic is of interest and value. However, further careful English editing is recommended to improve clarity and consistency. I also suggest addressing the minor issues listed below to enhance the overall quality of the manuscript.

L44. “so disaster events … cause” I do not understand what the point is . Please rephrase (or remove) this phrase.

L69. What previous interpretation? Please rephrase for clarity

L135. Remove the first “and”

L236. Please rephrase. Where does “…the same 2023” refer to?

L238-242: Please explain the reason for reporting that the top 10m are impermeable. Would it be possible for the water to infiltrate through another formation (upslope) and travel underground beneath that impermeable layer? At what depth was the slip surface located?

L299-200. Please rephrase, this sentence is hard to follow

L302. Susceptibility to landslides, not natural hazards

L308. Please rephrase “the area where it will be placed the head of the landslide”

L484. Please explain the percentages reported, they refer to the increase in risk? To number of incidents?

L491. What happened in the case of Romania?

L499. Not reported by IG. So does this mean that there was no seismic excitation in the area? Or the intensities were low to affect slope stability?

L504. PGA values reported are very low. Are you sure they are correct?

L66. What does Ha stand for?

L676-684. Even though the top layers are impermeable and not saturated, would it not be possible for an underlying formation to become saturated and form part of the slipping surface? Please comment if this is possible give the conditions of the area

Comments on the Quality of English Language

While the English has improved compared to the initial manuscript, some sentences remain unclear. Thorough proofreading is strongly recommended to ensure the manuscript's clarity and readability.

Author Response

Dear review,

We have responded to your comments in the attached file.

Thank you for your comments.

Kind regards

Author Response File: Author Response.docx