the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 12 Feb 2024
ECOMAN: an open-source package for geodynamic and seismological modeling of mechanical anisotropy
Abstract. Mechanical anisotropy related to rock fabrics is a proxy for constraining the Earth’s deformation patterns. However, the forward and inverse modelling of mechanical anisotropy in 3D large-scale domains has been traditionally hampered by the intensive computational cost and the lack of a dedicated, open-source computational framework. Here we introduce ECOMAN, a software package for modelling strain-/stress-induced rock fabrics and testing the effects of the resulting elastic and viscous anisotropy on seismic imaging and mantle convection patterns.
Differently from existing analogous software, the modelling of strain-induced fabrics has been extended to all mantle levels and it has been optimised to run across multiple CPUs, yielding strong scaling efficiency. In addition, shape preferred orientation (SPO)-related structures can be modelled and superimposed over lattice/crystallographic preferred orientation (LPO/CPO) fabrics, which allows the consideration of the mechanical effects of fluid-filled cracks, foliated/lineated grain-scale fabrics and rock-scale layering.
One of the most important innovations is the Platform for Seismic Imaging (PSI), a set of programs for performing forward and inverse seismic modelling in isotropic/anisotropic media using real or synthetic seismic datasets. The anisotropic inversion strategy is capable of recovering parameters describing a tilted transversely isotropic (TTI) medium, which is required to reconstruct 3D structures and mantle strain patterns and to validate geodynamic models.
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RC1: 'Comment on egusphere-2024-299', Anonymous Referee #1, 02 Apr 2024
General Comments
This paper presents a suit of tools related to the forward and inverse modelling of mechanical anisotropy. The capabilities which these tools provide are in my opinion a very important contribution to scientific progress within the scope of this journal. The paper described the purpose of the individual tools and explains at a high level what kind of changes level changes which where made (in case of being build on previous work), some considerations on how to use it and shows example explanations.
Unfortunately, there are, in my opinion, two major sections missing in this paper. The first sections is a proper methods section, which describes for each tool how it works. For example, what are the equations which are being solved. If it is based on previous work (such as D-REX), what changes have been made to the methods (more detailed then the current description) and how does this align with the assumptions made in the original code. What values of different parameters are used for computing for example wadsleyite or bridgmanite (both in D-REX and in the computation of the elastic tensor).
A second section which is missing is a benchmark section, to show that what is stated in the methods section actually works as intended. These should be at least a small suite of simple tests. For example computing the CPO in a simple shear environment, which can be matched against analytic results, the results of other codes and/or experiments. The only benchmarks which are shown are performance benchmarks.
Because these two sections are missing it is not possible to properly review the paper, since the authors do not show what they have done exactly and that they have done it correctly. Although the code is open-source, and it could in theory be checked by looking into the code and creating and running benchmarks yourself, I do think this should be part of the paper.
Specific comments
- The geodynamics code which are used for the examples should be mentioned. Looking at the references, it seems like for some of them I3MG is used, but this is not explicitly mentioned and it is not clear for all of them.
- Github is not a software archive, since it can easily be removed or changed. It is good to mention it, but you will also need a doi of for the software. You can get this for example from Zenodo.
- The repository has a license (MIT), a changlog document, a proper versioning scheme and a comprehensive user manual. I assume that this paper is about version 2.0, but this should be explicitly stated in the paper. I could not find any tests or benchmarks in the repository, although it could be that the cookbooks function as tests.
Technical corrections
line 135-137: Name and cite studies which are used together with the lookup tables. Also, it just states that the fabric selection is P-T dependent, so no water dependence? To come back to the general point, it needs to be explained how these fabrics are selected. A graph or table would be nice, if feasible.
line 361-362: Workstation is a vague term, mention CPU and ram needed to do that that calculation in the stated time.
line 428: I assume that the authors mean spreading memory load over several nodes, not CPU's.
Citation: https://doi.org/10.5194/egusphere-2024-299-RC1 -
RC2: 'Comment on egusphere-2024-299', Anonymous Referee #2, 25 Apr 2024
General commentsThe manuscript describes a suite of tools for the modelling of mechanical anisotropy, both its development for a given mineralogical model under geodynamic strain and the evaluation of various seismic parameters. The tools are (mostly) not new, but have been collated and refactored to make building them into a workflow simpler. The process of this workflow has also been nicely documented in an extensive manual for the suite, and several instructive examples.Such activities are often not well documented and shared, so I appreciate the extra efforts the authors have made to make their work accessible and useful to the community. While there are of course some limitations to all of the tools in the suite, there are a large range of important, interesting problems that can be tackled with these tools either singly or together which make the publication of a manuscript describing them worthy.I have some specific comments which I think that the authors should address before considering the manuscript finalised. These are (mostly) focussed on the seismic end of the problem. However, I would also like to endorse the general comments made by RC1, and agree that the two missing sections identified would make the manuscript much more complete. A version of record on Zenodo (or similar) would also be sensible.Specific commentsLine 30-33, sentence beginning "Seismological and ...": This implies that the suite presented does something different, which – as far as I can see – is not really the case. The calculations of (for example) SKS-splitting here is not done on the original geodynamics grid, for example. I'd also argue that this is not really as definitively a problem as stated, either.Line 81, s/b "At the same time ...": These are not the earliest examples of 3D anisotropy inversions. There are a range of these in the literature, dating back (at least) to Panning et al (GJI, 2006) for global models, shear-wave splitting (Abt and Fischer, 2008; Long et al, 2008; Wookey, 2012), and surface waves (Debayle et al, 2005), to name but a few.Line 279. s/b "the fraction of ...": It might be worth noting that the tensor 'fractions' from this approach have been suggested to not be a good approximation (Tape and Tape, Journal of Elasticity, 2024).Section 2.3.1: What equations are solved to calculated the splitting? How is the frequency included?Line 445, s/b: The underdetermination is inherent in the problem, at best MC sampling might be able to constrain the uncertainty due to the underdetermination, which is I suspect what the authors mean by this, but it should be clearer.Technical correctionsLines 318, 438: font issuesLine 39: 'in' -> 'of'Line 415: It is more useful to describe MATLAB and Python as interpreted languages, rather than high level. C is also technically a high level language, and is as fast or faster than Fortran.Line 417: '100.000s' -> '100,000s', or use words to avoid decimal point confusion.Line 424: 'it's' -> 'its'Line 451: 'surface waves' -> 'surface wave'Citation: https://doi.org/
10.5194/egusphere-2024-299-RC2
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