Detailed investigation of multi-scale fracture networks in glacially abraded crystalline bedrock at Åland Islands, Finland
- 1Geological Survey of Finland, P.0. Box 96, Espoo, FI-02151, Finland
- 2University of Turku, Department of Geography and Geology, Finland
- 1Geological Survey of Finland, P.0. Box 96, Espoo, FI-02151, Finland
- 2University of Turku, Department of Geography and Geology, Finland
Abstract. Using multiple scales of observation in studying the fractures of the bedrock increases the reliability and representativeness of the respective studies. This is because the discontinuities, i.e., the fractures, in the bedrock lack any characteristic length and instead occur within a large range of scales of approximately 10 orders of magnitude. Consequently, fracture models need to be constructed based on representative multi-scale datasets to enable valid interpolation and extrapolation of common scaling laws to all fracture sizes.
In this paper, we combine a detailed bedrock fracture study from an extensive bedrock outcrop area with lineament interpretation using Light Detection And Ranging (LiDAR) and geophysical data. Our study offers lineament data in an intermediary length range missing from Discrete Fracture Network -modelling conducted at Olkiluoto, a nuclear spent fuel facility in Finland. In addition, this study also provides a robust multi-scale fracture and lineament dataset which has been thoroughly analysed for the purposes of understanding the uncertainties and differences in the different datasets. Our analysis further covers the topological, scale-independent, fracture network characteristics.
Results of our study include the discovery of three distinct azimuth sets, N-S, NE-SW and WNW-ESE, both single scale and multi-scale power-law models for fracture and lineaments and further insight into a trend of decreasing apparent connectivity of fracture networks as the scale of observation increases. Specifically, a multi-scale power-law exponent of -1.13 is fitted to fracture and lineament lengths although we found that individually the fractures and lineaments might follow distinct power-laws rather than a common one.
Nikolas Aleksi Ovaskainen et al.
Status: open (extended)
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CC1: 'Comment on egusphere-2022-1363', Matthis Frey, 28 Dec 2022
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Dear Nikolas,
I saw that you cited our paper 'Interdisciplinary Fracture Network Characterization in the Crystalline Basement: A case study from the Southern Odenwald, SW Germany' (Frey et al. 2021) in your preprint. Thanks for this. Please note however that your citation refers to the preprint. The accepted article was published earlier this year: https://doi.org/10.5194/se-13-935-2022
Please change the reference accordingly.
Kind regards
Matthis Frey-
AC1: 'Reply on CC1', Nikolas Ovaskainen, 02 Jan 2023
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Hey Matthis,
Thank you for taking the time to notify about this! We will update to the proper citation as we continue our work on the manuscript. Using the preprint was an oversight.
Cheers,
Nikolas
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AC1: 'Reply on CC1', Nikolas Ovaskainen, 02 Jan 2023
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RC1: 'Comment on egusphere-2022-1363', Anonymous Referee #1, 10 Jan 2023
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The paper is well written, the methods up-to-date and the related results very interesting and statistically robust. The methods are adequately described, the limitation discussed and their reliability and representativeness of the obtained results considered as well. However, some further discussions on methods/results reliability and robustness are needed.
There is a main problem which undermines the possibility to publish the present manuscript in Solid Earth: the aim of the research is not clearly stated and thus it is not clear if the presented methods and results are significant or have any relevant implications for the case study or what are the broader implications for the general analyses of lineament maps from remote sensing. Stating clearly what are the aims and how the presented methods/results can answer to the research questions will also help in reorganizing logically the discussion sections. The paper would be also good if it was clearly focused on the presentation of the new analytical tools and the results adopted for the characterization of a case study, but still the case study need to have a clear aim. I think that the Authors can re-arrange the present manuscript with little effort in order to solve this main issue, otherwise I would suggest to redirect the manuscript to a more specialized journal.
Main issues:
- The aim of the research and the conclusions/implications of the results need to be explained a little bit more, they are not immediately understandable from reading the present manuscript. Especially in the Abstract, Introduction (where the aims are sparsely presented in bit and pieces) and in the conclusions.
- There is a discrepancy between the “results and conclusions” (sparsely) reported in the introduction section and the final Conclusions of the paper in Section 6. Are the methods and results presented here resolutive for the problem they aim to solve?
- The cut-off issue needs to be properly discussed in depth. What is the statistical significance of a results based on the analysis of only the 3% of the total dataset? Is it representative of the whole distribution? This needs to be discussed from the methodological point of view (is the analytical method adequate to analyse our dataset?). Is the results based on the 3% of the data representing the entire length distribution?
Minor comments.
- Some part need to be rephrased to be a little bit more concise (the part of the discussion regarding glacial erosion)
- Reconsider the use of “e.g.”,
- Rephrase the section Lines 92-99 : to be moved to the method section and integrated with the exiting description of the data source.
- Line 206: “?”?
Nikolas Aleksi Ovaskainen et al.
Nikolas Aleksi Ovaskainen et al.
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