Stress rotation  –  impact and interaction of rock stiffness and faults

Reiter, Karsten

doi:https://doi.org/10.5194/se-12-1287-2021

Articles | Volume 12, issue 6

https://doi.org/10.5194/se-12-1287-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/se-12-1287-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 12, issue 6

Research article

|

14 Jun 2021

Research article |

| 14 Jun 2021

Stress rotation – impact and interaction of rock stiffness and faults

Karsten Reiter

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Final revised paper (published on 14 Jun 2021)
Preprint (discussion started on 03 Aug 2020)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review', Anonymous Referee #1, 31 Aug 2020
- AC2: 'Comments on the review of Referee #1', Karsten Reiter, 24 Nov 2020
RC2: 'Stress rotation – The impact and interaction of rock stiffness and faults', Anonymous Referee #2, 12 Oct 2020
- SC1: 'Comment on the review of referee #2', Oliver Heidbach, 29 Oct 2020
- AC1: 'Comments on the review of Referee #2', Karsten Reiter, 01 Nov 2020

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Karsten Reiter on behalf of the Authors (18 Mar 2021) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (22 Mar 2021) by David Healy

RR by Anonymous Referee #1 (22 Apr 2021)

Suggestions for revision or reasons for rejection

The author modifications improved the overall quality of the manuscript, the writing, and the structure. The author provided detailed replies to my previous comments. Furthermore, the modifications in Figure 11 and the new Figures (Table 1 and Figure 13) are valuable assets to this publication. However, in places, I found that incorporating further some of the contents of the author’s replies within the manuscript could be valuable for the readers (see main comments below). Besides, although the text has been improved from the first version, I found that there are still some unclear sentences (see some potential suggestions in technical comments). For this reason, I suggest the publication of this manuscript after a Moderate revision.

Main comments
• Table 1 is a summary of previous works from the literature. I think this table is a great asset in the publication. However, most of the data in this table show maximum values of rotations of 90, which is somehow not very informative. Maybe providing other values, like an average rotation or a rotation at a distance from the perturbation sources could be more informative. Besides, a value of 90 could also correspond to a stress permutation between Sh and SH, which can be related to changes in the magnitudes of the stress rather than the rotation of the stress. This may be somehow worth discussing to avoid confusion.

• The author clarifies the initial stress conditions by adding Section 4.4. The author also clarifies the boundary conditions in his reply and Section 6.2 of the manuscript. Even if this is now clearly stated in Section 6.2, I will suggest adding a few general sentences in section 4.5 for the readers. For example: “The boundary conditions are defined by displacement. They are calibrated on the reference model. The same boundary conditions are applied to all the different models.”

• The author answered the comments concerning the dip of the contacts between the units in his reply. Here again, maybe adding some of the information from the reply in Section 4.1 will be valuable for the readers. For example: “More complex geometries and variable dip angle may result in different stress patterns as the ones obtained for vertical discontinuities, however, studying such variability is beyond the scope of this paper.”

• The choice of the material properties is now more clearly discussed in Section 6.2 and the potential effect of failure are also discussed in Section 6.7.

• I found the discussion interesting and detailed. But it is a bit difficult to follow, partly due to the numerous sections, which are sometimes very small. For simplification, maybe the author could group Sections 6.1 and 6.2. Similarly, maybe Section 6.4 could be incorporated in Section 6.5.

Technical comments
• L.12: ‘the horizontal stress orientation’ maybe remove ‘orientation’.
• L.13: ‘in the order of up to 78’ remove ‘in the order of’.
• L.14: ‘not only regions near the material transition (<10 km) are affected by this stress rotation’ this is unclear.
• L.232: See also Roche and Van der Baan 2015 and 2017 for references. (Roche, V., & Van der Baan, M. (2015). The role of lithological layering and pore pressure on fluid‐induced microseismicity. Journal of Geophysical Research: Solid Earth, 120(2), 923-943.).
• L.240: ‘imagined’ maybe ‘virtual’ is a better term.
• L.268: ‘Mechanical’ replace by ‘Mechanically’.
• L.270: ‘Therefore, the unit stiffness are from the deformable to the rigid ones: RHZ _ NPZ < STZ <
• MGCH _ MZ’ This is not very clear. Also, replace ‘stiffness by stiffnesses’.
• L.278: ‘no rotation is to observe’ replace by ‘no rotation is observed’.
• L.279: ‘turns more counter-clockwise’ remove ‘more’.
• L.286: ‘in the large density units’ remove ‘the’.
• L.300: ‘Within the models having three’ replace by ‘For the models with three’.
• L.317: ‘of a significant Young’s modulus contrast with a cohesionless contact’ replace by ‘between a significant Young’s modulus contrast and a cohesionless contact’.
• L. 321: ‘point out significant larger rotation than for the stiff units’ replace by ‘shows larger rotations than the model with stiffer units’.
• L.324: ‘In the models with the alternating stiffness with the low friction discontinuities (|E|e|E| and |e|E|e|) generate’ replace by ‘ The models with alternating stiffnesses and low friction discontinuities (|E|e|E| and |e|E|e|) generate’.
• L.334: ‘The same can be observed less pronounced in the observed SHmax orientation’ replace by ‘In Figure 11c, these areas show similar, but less pronounced, rotation of SHmax’.
• L.343: ‘It is really unlikely that … as a result’. This is not clear, replace by ‘Chosen properties are constant over a depth of 30 km, which is unlikely. Even for a given lithology, the properties can change with depth, as a result of’.
• L.394: ’only 31 rotation’ ‘only a 31 rotation’.
• L.404: remove capital at ‘model’.
• Figure 3: ‘Poissons ratio’ replace by Poisson’s ratio
• Figure 12: ‘counterbalances’ replace by ‘counterbalance’
• Figure 13: replace max. rotation [°].

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ED: Publish subject to minor revisions (review by editor) (22 Apr 2021) by David Healy

AR by Karsten Reiter on behalf of the Authors (29 Apr 2021) Author's response Author's tracked changes Manuscript

ED: Publish as is (30 Apr 2021) by David Healy

ED: Publish as is (03 May 2021) by Federico Rossetti (Executive editor)

AR by Karsten Reiter on behalf of the Authors (10 May 2021)

Short summary

The influence and interaction of elastic material properties (Young's modulus, Poisson's ratio), density and low-friction faults on the resulting far-field stress pattern in the Earth's crust is tested with generic models. A Young's modulus contrast can lead to a significant stress rotation. Discontinuities with low friction in homogeneous models change the stress pattern only slightly, away from the fault. In addition, active discontinuities are able to compensate stress rotation.