We sincerely thank Anonymous Referee #1 for the careful and constructive evaluation of our manuscript and for the positive assessment of the integrated geological–geophysical approach. We have addressed the requested revisions wherever the available records and data allow us to do so. The changes are detailed below.

Comment 1 – Reference accessibility

Reviewer comment:

Improve reference accessibility. Some references (e.g., institutional reports) may be difficult to locate. Please add DOIs and/or stable URLs where available.

Response:

Thank you for this suggestion. We reviewed the reference list and added DOIs where available. For institutional reports, governmental documents, and other grey-literature sources without a DOI, we added stable institutional or repository URLs whenever these could be identified. Bibliographic information was also standardized and access dates were included where appropriate.

These changes improve the traceability and accessibility of the documentary sources used to establish the geological, hydrological, and geomorphological context of the study area.

Comment 2 – Seasonality of the landslide and ERT acquisition

Reviewer comment:

Seasonality (rainy-season failure vs. drier-season ERT): add a short qualitative discussion. The landslide occurred in a rainy-season window, whereas ERT was conducted in a comparatively drier period...

Response:

We agree with the reviewer that the temporal difference between the November 2021 landslide and the conditions prevailing during the later ERT survey is important for interpretation. We have therefore added a short discussion emphasizing that the ERT models represent the electrical conditions of the slope at the time of acquisition and should not be interpreted as a direct reconstruction of the hydrological conditions that existed during the 2021 failure.

The revised Discussion now includes the following text:

“The main landslide occurred during the October–December wetter period identified for the study area, whereas the ERT survey represents later and comparatively drier post-event conditions. Consequently, the resistivity distribution obtained in this study should be considered a temporal snapshot of the subsurface electrical structure rather than a direct reconstruction of the hydrological conditions prevailing during the November 2021 failure. Variations in pore-water content and hydraulic connectivity may modify bulk electrical resistivity, and therefore part of the observed conductive response may vary seasonally, whereas other persistent anomalies may reflect lithological or structural controls.”

“Repeated ERT measurements during wet and dry seasons would provide an important complement to the present dataset. A time-lapse comparison could reveal whether low-resistivity domains increase in extent or lateral continuity during wetter conditions and whether some conductive zones persist independently of seasonal moisture changes. Such observations would help distinguish transient moisture-related effects from more persistent lithological or structural controls. Because repeated seasonal ERT measurements were not available in the present study, this distinction cannot be assessed directly and represents a limitation of the current dataset.”

This modification also makes our interpretation of the low-resistivity domains more cautious.

Comment 3 – Location and orientation of Figure 10(a,b)

Reviewer comment:

Figure 10(a,b): unclear location relative to maps. Please add an inset/annotation showing where Figure 10(a,b) corresponds on the site maps (ERT layout / stratigraphic points), including viewpoint/orientation if possible.

Response:

Thank you for pointing this out. Figure 10 has been revised to make the spatial relationship among the field photograph, geological observations, stratigraphic Column A, and ERT Profile 2 clearer. A locator panel has been added showing the landslide boundary, the position of ERT Profile 2, the location of Column A, and the approximate location of the outcrop represented in the photograph and geological sketch. Geographic orientation is also indicated where possible.

The revised figure therefore allows the reader to evaluate more directly the spatial basis for the geological–geophysical comparison.

The caption has also been revised accordingly:

“Figure 10. Integration of geological and geophysical observations used in the interpretation of the mass movement. (a) Field photograph showing the present exposure and slope conditions. (b) Geological sketch representing the observed arrangement of the exposed units. (c) Stratigraphic Column A showing the principal volcaniclastic units and sampling/observation levels. (d) Electrical Resistivity Tomography Profile 2, showing the main subsurface resistivity contrasts. (e) Location map showing the Aloburo landslide boundary, ERT Profile 2, Column A, and the approximate location of the outcrop represented in panels (a) and (b). The panels are presented together to illustrate the spatial relationship between surface geological observations and the geoelectrical response.”

Comment 4 – Reproducibility of the low-cost ERT system

Reviewer comment:

Low-cost custom ERT system: provide minimal reproducibility details... injection signal, current and voltage measurement, multimeter model numbers and specifications, CT ratio, and a calibration/verification check.

Response:

We appreciate this important comment and agree that these parameters would improve the reproducibility of the custom ERT system. We have carefully reviewed the available field notes and documentation associated with the instrument.

The information that can be reliably documented is that the system used a 12 V DC battery as the primary power source, which was converted to approximately 220 V AC for current injection through electrodes A and B. The potential difference was measured between electrodes M and N using a multimeter, while the injected current was monitored using a second multimeter in conjunction with a current transformer. These measured quantities were subsequently used to calculate the apparent resistivity according to the Wenner relation:

[

\rho_a = 2\pi a\frac{\Delta V}{I}.

]

However, because the system was an experimental, non-commercial prototype assembled for field teaching and research activities, some detailed construction and calibration records are no longer available. In particular, we cannot reliably recover the exact injection frequency and waveform characteristics, the model numbers and complete technical specifications of the two multimeters, the current-transformer ratio, or the details of a resistor-based calibration test. We therefore prefer not to reconstruct or infer these values retrospectively.

To avoid overstating the reproducibility of the instrumentation, we have revised the manuscript to report only the technical characteristics that can be verified from the available documentation and have added the following limitation:

“The ERT acquisition system used in this study was a low-cost, non-commercial prototype developed for academic field applications. The available records document the general measurement configuration, including a 12 V DC power source converted to approximately 220 V AC, current injection through electrodes A–B, potential-difference measurement across electrodes M–N, and current monitoring using a multimeter and current transformer. However, complete archival documentation of some electronic specifications, including the exact signal frequency and waveform, multimeter model specifications, current-transformer ratio, and detailed calibration records, is no longer available. Consequently, these parameters cannot be reported retrospectively without introducing unsupported assumptions. This limitation should be considered when assessing the full instrumental reproducibility of the survey.”

We have also revised the wording of the manuscript so that the low-cost character of the system is presented as an implementation feature of this case study rather than as a fully reproducible instrumental design.

We recognize that this does not provide all the instrumentation details requested by the reviewer. Nevertheless, we believe that explicitly documenting the information that is available, while transparently identifying the information that cannot be recovered, is preferable to estimating or reconstructing undocumented technical specifications.

Closing response

We thank the reviewer again for the constructive comments. The revisions have improved the accessibility of the references, clarified the temporal limitations associated with seasonal moisture conditions, strengthened the spatial integration presented in Figure 10, and made the description and limitations of the custom ERT system more transparent. We believe that these changes improve the methodological clarity and scientific robustness of the manuscript.

We sincerely thank the commenter for the careful reading of our manuscript, the positive assessment of the figures and integrated interpretation, and the constructive suggestions for improving the work. We particularly appreciate the recognition of the practical value of the non-commercial ERT system and the geological information contained in the inversion results. We have addressed the comments as follows.

Comment 1 – Additional references in the Introduction

Comment:

The introduction begins with classic studies and proceeds in a linear fashion to specific studies on geophysics applied to the subject under investigation. This section is supported by relevant studies, but these are few and far between in the text; therefore, it is recommended that additional works be included.

Response:

Thank you for this suggestion. We agree that the original Introduction relied on a relatively limited number of references concerning the application of ERT to landslide investigation.

The Introduction has therefore been revised to provide a more focused review of previous applications of electrical resistivity methods to landslides, particularly studies dealing with the identification of conductive zones, subsurface heterogeneity, water-related resistivity changes, and the integration of geophysical information with geological observations.

At the same time, redundant explanations of the general advantages of ERT have been reduced so that the revised Introduction places greater emphasis on the scientific motivation for integrating ERT with field stratigraphy in the San José de Aloburo case study.

This revision better situates the present work within previous landslide-geophysics research and clarifies that the novelty of the study lies primarily in the geological–geophysical integration and its application in a volcaniclastic Andean setting rather than in the use of ERT alone.

Comment 2 – Equipment subsection and electrical characteristics

Comment:

I believe a subchapter on the equipment is unnecessary; the text can proceed without subdivisions. The equipment is simple and interesting, but information regarding the power and current intensity used is lacking.

Response:

We agree that the description of the equipment can be presented more concisely. The methodological section has therefore been reorganized so that the description of the acquisition system is integrated into the ERT acquisition methodology rather than emphasized as an independent methodological component.

We also agree that information concerning the electrical characteristics of the system is important for evaluating the acquisition procedure.

The information that can be reliably documented from the available records is that the system used a 12 V DC battery as the primary power source, which was converted to approximately 220 V AC for injection through electrodes A and B. The potential difference was measured between electrodes M and N, while the injected current was monitored using a second multimeter together with a current transformer. These measurements were subsequently used to calculate apparent resistivity according to the Wenner relation.

However, because the instrument was a non-commercial prototype developed for academic field applications, the archived documentation does not contain reliable records of the exact current intensity or power delivered during the individual field measurements. We therefore prefer not to reconstruct or estimate these values retrospectively.

The revised manuscript now explicitly acknowledges this limitation rather than reporting unsupported instrumental values. A statement has been added indicating that the lack of complete archived electrical specifications limits full instrumental reproducibility, although the acquisition geometry and general measurement configuration remain documented.

We believe that this transparent treatment is preferable to introducing estimated values that cannot be independently verified.

Comment 3 – Deeper discussion of the inversion models

Comment:

The inversion models reveal interesting geological features that are, however, scarcely discussed; they deserve further elaboration.

Response:

We agree. The Discussion has been expanded to analyze the resistivity profiles more critically and to distinguish more clearly between measured geoelectrical patterns and their geological interpretation.

The revised manuscript now discusses:

• the geometry and spatial distribution of the main low- and higher-resistivity domains;
• differences and similarities among the four ERT profiles;
• the relationship between shallow resistivity contrasts and the available stratigraphic observations;
• the possible influence of moisture, lithology, grain size, porosity, weathering, and subsurface heterogeneity on the observed electrical response;
• the non-uniqueness of resistivity interpretation;
• the reduced lateral sensitivity of the Wenner configuration;
• and the decrease in spatial resolution with depth.

The interpretation has also been made more conservative. Low-resistivity zones are no longer treated as uniquely diagnostic of saturated or weak materials. Instead, they are interpreted as conductive geoelectrical domains that may be consistent with increased moisture and/or comparatively conductive volcaniclastic materials when supported by geological observations.

Similarly, boundaries previously described directly as rupture planes are now referred to more cautiously as interpreted potential rupture zones or geoelectrical boundaries consistent with possible shear/rupture zones, because the ERT data alone do not provide direct mechanical confirmation of a slip surface.

These revisions allow the inversion results to play a more meaningful role in the Discussion while avoiding interpretations that exceed the resolving capability of the available dataset.

Comment 4 – Fence diagram rather than 3D model

Comment:

In fact, the integration of the models allowed for the generation of a fence diagram rather than a 3D model.

Response:

We fully agree and thank the commenter for identifying this terminology issue.

The previous term “3D model” was not technically accurate because the four ERT sections were inverted independently in two dimensions and subsequently positioned in their corresponding spatial locations. No volumetric three-dimensional resistivity inversion was performed.

Therefore, throughout the revised manuscript, the terminology has been changed to:

“3D fence diagram of independently inverted 2D ERT profiles.”

The corresponding section title, Figure 7 caption, Results, and Discussion have been revised accordingly.

The manuscript now also explicitly states that the fence diagram is intended to facilitate spatial comparison among the individual 2D resistivity sections and should not be interpreted as demonstrating continuous three-dimensional resistivity structures between the profiles.

This correction provides a more accurate description of the processing and visualization approach used in this study.

Closing response

We sincerely thank the commenter for the constructive and encouraging assessment. In response to these suggestions, we have strengthened the literature context of the Introduction, simplified and clarified the presentation of the custom ERT equipment, explicitly acknowledged the limitations associated with unavailable electrical specifications, expanded the geological and geophysical interpretation of the inversion models, and corrected the terminology of the spatial profile integration from a “3D model” to a 3D fence diagram.

We believe that these changes improve the methodological transparency, interpretive rigor, and overall clarity of the manuscript.

We sincerely thank Anonymous Referee #2 for the careful and critical evaluation of our manuscript and for recognizing the value of the ERT measurements obtained using the non-commercial instrumentation developed at our institution. We particularly appreciate the reviewer’s acknowledgement of the challenges associated with the study area and the potential scientific value of the dataset.

We understand the reviewer’s concern regarding the survey design and spatial coverage. The acquisition geometry was strongly constrained by field accessibility, the morphology of the landslide, the presence of damaged terrain and infrastructure, and the practical limitations of the low-cost manual acquisition system. We have therefore revised the manuscript to describe these constraints more explicitly and, importantly, to limit the spatial scope of our conclusions. The revised manuscript no longer implies that the four ERT profiles provide a complete three-dimensional characterization of the entire landslide body. Instead, they are presented as complementary 2D sections that primarily characterize the upper and accessible portions of the affected slope.

We also agree with the reviewer’s main scientific concern that some interpretations in the original manuscript were expressed with a level of certainty greater than that supported by the ERT data alone. We have therefore substantially revised the Results, Discussion, figure captions, and Conclusions to distinguish more clearly between:

1. measured and inverted electrical resistivity patterns;

2. geological observations obtained independently in the field; and

3. geological interpretations inferred from their integration.

In particular, low-resistivity zones are no longer interpreted uniquely as saturated, fractured, or low-cohesion materials. They are now described as conductive geoelectrical domains that may be consistent with increased moisture content, finer or more conductive volcaniclastic materials, weathering, and/or other subsurface conditions. Their geological significance is discussed only where supported by the available stratigraphic and geomorphological observations.

Similarly, boundaries previously referred to directly as “rupture planes” have been reconsidered. Where appropriate, we now use more cautious terminology such as “interpreted potential rupture zone” or “geoelectrical boundary consistent with a possible shear/rupture zone.” This change reflects the fact that ERT identifies contrasts in electrical properties and cannot, by itself, uniquely demonstrate the presence or exact geometry of a mechanical rupture surface.

The spatial visualization of the four profiles has also been revised. The previous term “3D model” has been replaced by “3D fence diagram of independently inverted 2D ERT profiles,” because no true three-dimensional resistivity inversion was performed. The revised text now makes clear that this representation is intended only to facilitate comparison among the 2D sections and does not demonstrate continuous resistivity structures between profiles.

In addition, the Discussion has been expanded to address the principal methodological limitations of the study, including the non-uniqueness of ERT inversion, decreasing resolution with depth, reduced lateral sensitivity of the Wenner configuration, the limited spatial coverage of the survey, the absence of direct geotechnical control at depth, the temporal difference between the 2021 landslide and the later ERT acquisition, and the limited extent of the quantitative granulometric dataset.

We have also added contextual information where requested and revised the integration between the ERT profiles, stratigraphic columns, field observations, and geomorphological evidence. The revised manuscript avoids one-to-one equivalence between resistivity contours and geological contacts and instead presents these relationships as interpretations constrained by independent geological observations.

Finally, the role of the low-cost instrumentation has been described more carefully. We retain it as an important practical aspect of the study, while explicitly acknowledging the limitations of the available instrumental documentation and avoiding claims that exceed the reproducibility supported by the archived records.

We thank the reviewer for identifying these issues. The comments prompted us to substantially reduce interpretive overstatement and to better separate observation from inference throughout the manuscript. We believe that the revised version is scientifically more cautious, transparent, and consistent with what can be supported by the available ERT and geological data.

Detailed responses to each of the reviewer’s comments and suggestions in the annotated supplement are provided below.