Potential Fault Displacement Hazard Assessment Using Stochastic Source Models: A Retrospective Evaluation for the 1999 Hector Mine Earthquake

Round 1

Reviewer 1 Report

Dear editor and author:

The paper is an interesting contribution to the knowledge about fault displacement hazard analysis and applied in practice. A very good contribution to GeoHazard.

The paper proposes an alternative approach based on stochastic source modelling to fault displacement analysis using Okada equations, and it is checked in the 1999 Hector Mine earthquake from a retrospective perspective. It is well written and neat and clearly presented. Figures material are good. the introduction provides sufficient background and include all relevant references (I only suggest two more references), the conclusions are supported by the results.

My only concern and suggestion is that if what is proposed is a new method, it should be checked not only in an earthquake but also to try to prove if it is valid in several more examples. Has the author tried to test this methodology in another earthquake? I understand that this suggestion may be excessive work for the purpose of this article, but I believe that validating this method in two more earthquakes made this article a reference.

Two suggested references to be considered(I have nothing to do with the authors but they are quite news on the topic)

Wells, D.L., and Kulkarni, V.S., Probabilistic and Deterministic Fault Displacement Hazard Analysis – Sensitivity Analyses and Recommended Practices for Developing Design Fault Displacements. Proceedings of the 10th National Conference in Earthquake Engineering, Earthquake Engineering Research Institute, Anchorage, AK, 2014.

Katona, T.J.; Tóth, L.; Győri, E. Fault Displacement Hazard Analysis Based on Probabilistic Seismic Hazard Analysis for Specific Nuclear Sites. Appl. Sci. 2021, 11, 7162. https://doi.org/10.3390/app11157162

Author Response

Please see the uploaded file.

Author Response File: Author Response.pdf

Reviewer 2 Report

In this work, the author proposes a new approach for probabilistic seismic hazard analysis based on stochastic source modelling and fault displacement analysis using Okada equations. This approach can be applied both to retrospective and prospective evaluations. In this paper, the author applies this approach for a retrospective evaluation of the 1999 Hector Mine earthquake. A future work will take into account the prospective evaluation of PFDHA.

After an Introduction, the author shows the methodology of this approach as well as the formulation, the stochastic source modelling and fault displacement modelling. The main advantages that this approach have compared to already published PFDHA models are: i) all fault mechanisms can be considered (for example, Petersen et al., 2011 is only for strike-slip events, Youngs et al., 2003 is only for normal events…), and ii) three translational displacements can be obtained for a given location. There are also some limitations, such as the Mw range of applicability. The statistical scaling relationships are for Mw <= 7.5. After this section, the author introduces the 1999 Hector Mine earthquake showing the fault trace, GPS displacement vectors, displacement offset along the fault trace, and existing inverted earthquake source models. In conclusion, the author shows results for retrospective fault displacement hazard analysis of this event explaining the model set-up and showing comparison of simulated displacement at GPS stations based and simulated horizontal and vertical offsets along the fault trace. A comparison of simulated total offsets along the fault trace with the prediction based on Petersen et al. 2011 as well.

The manuscript is well written, clear, and it tackles an important topic such as probabilistic fault displacement hazard. I warmly recommend it for publication after the following general comments:

• Some important references are missing in the introduction.
• In my opinion it would be necessary, at least, refer which Okada equations have been used in this work. In Okada 1985 there are 42 equations!
• I would like to see (maybe in an appendix) also results that you can get using others inverted earthquake source models. (see comment at line 243 in the attached pdf)
• I think that in figure 12, you should compare Petersen 2011 only with the simulated horizontal offset displacements. (see comment at line 377-378 in the attached pdf)
• Address other minor comments in the attached pdf.

Comments for author File: Comments.pdf

Author Response

Please see the uploaded file.

Author Response File: Author Response.pdf