Investigating the Stability of the Hill of the Acropolis of Athens, Greece, Using Fuzzy Logic and Remote Sensing Techniques

Round 1

Reviewer 1 Report

The paper investigates the stability of the Acropolis Hill, Greece using fuzzy logic techniques. The method is relatively simple, based on six factors and experts judgment to weight these variables. The validation process was performed by comparing with results of satellite data of ground movement, which are new. The paper is generally well-written and scientifically sound. The paper can be improved if the following are applied: 1.Equations are numbered 2.Experts are described in more detail: what requirements do they have in terms of expertise, experience, etc 3. As the method is a simplified one, its limitations must be described. Furthermore, the manner that improvements in the stability assessment of proposed method may be described. More specifically: (a) Regarding seismic risk analysis, hazard depends on the intensity of the applied acceleration and this acceleration may depend on local effects, especially as a result of topography (Bouchon et al., 1996, Bouckovalas et al, 2005, Stamatopoulos et al, 2007). The effects may be obtained by numerical analyses and/or accelerometers measurements and may be included in improved analysis. (b) In the paper it is discussed that a number of recorded rock instability and bedrock failures data exists. This data may also be included in improved risk analysis. (c) It should be discussed if stability analyses have been performed in the slopes of the hill and if the results of such analyses are available. Also, the manner that the results of such analyses may also be included in improved risk analysis should be discussed. References Bouchon, M., & Barker, J. S. (1996). Seismic response of a hill: the example of Tarzana, California. Bulletin of the Seismological Society of America, 86(1A), 66-72. Bouckovalas, G. D., & Papadimitriou, A. G. (2005). Numerical evaluation of slope topography effects on seismic ground motion. Soil Dynamics and Earthquake Engineering, 25(7-10), 547-558. Stamatopoulos, C. A., Bassanou, M., Brennan, A. J., & Madabhushi, G. (2007). Mitigation of the seismic motion near the edge of cliff-type topographies. Soil Dynamics and Earthquake Engineering, 27(12), 1082-1100.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

This work presents a logically designed, straightforward application of both active (Insar) and passive (very high resolution airborne optical) remote sensing technologies to validate a fuzzy indexing approach to rock instability mapping - which is appropriate for publication in the Remote Sensing journal. The application to a culturally and historically important resource  - the Acropolis in Athens - is timely as global climate change progresses, and may serve as a model for application to other such resources where similar data and expert knowledge bases exist.  The authors provide a reasonable discussion and interpretation of their results, and identify areas where this model can be improved and extended. 

Specific comments to be addressed prior to publication (referenced by manuscript line number):

131: The approach to determination of the six relevant variables used in the study is not well described - was this purely subjective based on the expertise of the authors, or was some type of literature analysis performed to inform the selection?

147: Vegetation is explicitly mentioned as a significant variable associated with rockfall, yet it does not appear to be incorporated into the subsequent fuzzy determination model. 

235: The approach described here seems to be semi-quantitative, with the orientation of bedding being based on expert input. Assuming there is quantitative orientation data available (eg strike and dip), would a completely quantitative solution be possible?

238: While the rest of the manuscript is generally well-written, I found this paragraph hard to follow.  It would be better to use discrete sentences for each of the four formations. A general geologic map and cartoon cross-section of the Hill geology would also be useful here to set context for the subsequent figures.

282: Was the accuracy of the edge detection approach validated by field measurements? In particular, the potential presence of shadows in the image may introduce false positives in edge detection techniques.

296. It is not clear how the methodology of image analysis discriminated between discontinuities and faults. Was this achieved through geologic mapping or some other dataset? It seems there is a high potential for redundancy with the density of discontinuity dataset, leading to incorrect weighting in the fuzzy model. Was the effect of only using the discontinuity variable - as it seems to include faults (eg 5 variables instead of six) on the RIM output assessed?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf