Source Parameter Inversion and Century-Scale Stress Triggering Analysis of the 2021 Maduo M_W7.4 Earthquake Using GNSS and InSAR Displacement Fields

Round 1

Reviewer 1 Report

In this paper, the co-seismic slip model and fault plane stress distribution of the Maduo earthquake were obtained using GNSS and InSAR data inversion. Three co-seismic sliding models were calculated based on different data sources. Cumulative Coulomb stress changes on the rupture zone from co-seismic, post-seismic, and inter-seismic events have been investigated by calculating the stress perturbations in the surrounding area, From the results, this paper provides valuable academic insights for assessing the future seismic risk of the region, and the experimental content has some academic reference significance, but there are some questions in the paper that need to be answered or modified by the authors:

1. Authors are advised to streamline the content section of the abstract describing the results appropriately.

2. The following elements exist for the author to answer or revise in the first part:

a) The logical relationship of the author 's introduction is somewhat chaotic, and the background span is large. It is suggested that the author should make some revisions after careful consideration.

3. The following elements exist for the author to answer or revise in Part II:

a) It is recommended that the authors list the core formulas of the SDM algorithm;

b) In the second part, the author describes that the L-shaped curve method is used to determine the optimal smoothing factor. It is suggested that the L-shaped curves of three sliding distribution models should be given and added to the appropriate position ;

c) For the joint inversion of the Maduo co-seismic sliding model with GNSS and InSAR data, the authors seem to have described the problem of setting the weights between the different kinds of data with only a few sentences of methodological nomenclature, and the subsequent description "Given that GNSS observations consist of only 81 data sets, which is significantly fewer compared to InSAR data, a weight of 100 is assigned", seems to be a subjective idea, which is not related to the above mentioned method terms, and the cited literature [49] is not intuitively convincing and not well understood by the authors. persuasive, and do not quite understand the meaning of the author's description of this sentence, the author is asked to explain this relevantly.

4. The author has the following elements in Part III that require an answer or revision by the author:

a) Table 6, for GNSS+InSAR sliding distribution description results need to be centered;

b) There are some figures in this section where the font and legend are small and illegible, and the authors are advised to check and replace them.

5. For the third of the conclusions, it is recommended that the authors add a relevant explanation of why the stresses calculated by the co-seismic sliding model inverted from GNSS data are different from the other two models.

6. There are some grammatical errors in this article. It is suggested that the author should check the full text and change it carefully.

7. Some papers can be useful for revision:

A New Method of Variational Bayesian Slip Distribution Inversion.Journal of Geodesy, 2023, 97(1):10, DOI: 10.1007/s00190-023-01701-9

Transient Deformation Excited by the 2021 M7.4 Maduo (China) Earthquake: Evidence of a Deep Shear Zone,August 2023,Journal of Geophysical Research: Solid Earth https://0-doi-org.brum.beds.ac.uk/10.1029/2023JB026643

Cascading rupture process of the 2021 Maduo, China earthquake revealed by the joint inversion of seismic and geodetic data https://0-doi-org.brum.beds.ac.uk/10.1016/j.tecto.2023.229732

After answering the above questions, the author should carefully check the content of the full text and revise it according to the above suggestions, and refine the articles and sentences.

Moderate editing of English language required.

Author Response

Author Response File: Author Response.docx

Reviewer 2 Report

The objective of this paper is to study the source parameter inversion and century-scale stress triggering analysis of the 2021 Maduo Mw7.4 earthquake using GNSS and InSAR displacement fields. In particular, this paper employs GNSS and InSAR data inversion to obtain the co-seismic slip model and fault plane stress distribution of the Maduo earthquake, while the stress disturbance to the surrounding area is calculated based on the co-seismic slip model derived from different data sources. Moreover, the Coulomb stress evolution, resulting from the co-seismic and post-seismic viscoelastic relaxation effects of 14 historical strong earthquakes is calculated by implementing a layered viscoelastic medium mode. Additionally, the Coulomb stress changes, which are related to inter-seismic tectonic stress loading, are evaluated for 19 fault segments, while the cumulative Coulomb stress changes resulting from co-seismic, post-seismic, and inter-seismic effects on the fault zones are explored.

This is an interesting and well-structured paper. All necessary sections (Introduction, Materials and Methods, Results, Discussion, Conclusions) have been considered. Moreover, the “Materials and Methods” and “Results” sections are divided into sub-sections, providing additional details. Furthermore, all Figures, Tables and Diagrams are consistent with the analysis provided in the manuscript. Regarding the mathematical part, predominantly analyzed in the “Method of co-seismic slip distribution inversion” sub-section, it is valid and accurately explained. However, some changes should be implemented, which will improve the paper. In particular:

Lines 9-33: Although the abstract has been properly structured, unnecessary details are contained (these details could be placed in the manuscript). The abstract should be clear and concise, while the most significant processes/findings/conclusions should be highlighted. Please, modify the abstract by reducing its length.

Lines 55-56: This sentence should be further explained, while it is necessary to provide some global examples, related to the effect of stress accumulation on neighboring active faults. Typical papers, in which the corresponding information can be obtained and optionally be cited, are the following: 1. Mildon, Z. K., Toda, S., Faure Walker, J. P., & Roberts, G. P. (2016). Evaluating models of Coulomb stress transfer: Is variable fault geometry important? Geophysical Research Letters, 43(24). https://0-doi-org.brum.beds.ac.uk/10.1002/2016GL071128, 2. Sboras, S., Lazos, I., Bitharis, S., Pikridas, C., Galanakis, D., Fotiou, A., Chatzipetros, A., Pavlides, S., 2021. Source modelling and stress transfer scenarios of the October 30, 2020 Samos earthquake: seismotectonic implications. Turkish Journal of Earth Sciences 30, 699–717. https://0-doi-org.brum.beds.ac.uk/10.3906/yer-2107-25, 3. Toda, S., & Enescu, B. (2011). Rate/state Coulomb stress transfer model for the CSEP Japan seismicity forecast. Earth, Planets and Space, 63(3), 171–185. https://0-doi-org.brum.beds.ac.uk/10.5047/eps.2011.01.004. Please, apply.

Line 149: Please, provide a more detailed description in the Table 2 caption and correct the parentheses of “Slip rate”.

Lines 163-168: Please, provide a brief explanation about the reference frame if the GNSS data.

Lines 169, 178 and 193: Similarly, please provide more detailed descriptions in the Table 3, 4 and 5 captions, respectively.

Line 260: Please, provide Figure 2 in a higher resolution. It contains blurry parts in the current form.

Lines 263-264: Please, provide Figure 3 in a higher resolution, as well as a more detailed description.

Lines 480-489: This part of the “Conclusions” section could be removed (or reduced its length), as it is repetitive and resembles the abstract. The numbering of the concluding remarks should be maintained. Please apply.

Author Response

Dear Reviewer

Thank you very much for your careful review of the manuscript. Your suggestions and questions are very helpful for us to improve the quality of the article. We have made careful modifications in the text according to your suggestions. We also made a point-to-point reply. Response to Reviewer2.docx

Author Response File: Author Response.docx

Reviewer 3 Report

 The authors mainly conducted two important works. Firstly, the co-seismic source parameters and fault plane stress distribution related to the 2021 Maduo M_W7.4 earthquake was obtained finely based on the layered crustal model constrained by combining GNSS and InSAR observations. Secondly, the inter-seismic stress evolution map with century-scale was constructed considering the co-seismic and post-seismic viscoelastic relaxation effects and the stress loading and unloading impact of 14 historical strong earthquakes in the research area since 1900.The research content is detailed and will arouse strong interest from readers.

This manuscript deserves to be published as soon as possible after the minor revision. The detailed modifications and suggestions are as follow:

1.     Each subgraph in Figure 1 should be numbered or combing the three subgraphs into a figure. In addition, I suggest deleting the global location map in the lower right corner of Figure 1.

2.     The text of the color mark in Figure 3 is small and the display is not clear. It is recommended to adjust the font size.

3.     Line 411, “threshold of 0.01 MPa”. What is the rationale behind? Please provide relevant references.

4.     Line 68, the magnitude of the symbol expression please note that the unified format.

5.     The conclusion part focuses on the analysis of the stress loading part of the fracture section, please add the stress unloading factors and analyze and assess the seismic risk more objectively.

6.     In this paper, 14 strong earthquakes with M > 7 since 1900 are selected as historical strong earthquakes. What are the reasons for the selection?

      7.     Pay attention to the expression of the technical terms. “earthquake's cause”          should be revised as” the seismogenic mechanism”. 

     some English grammar problems need to revised, e.g,  “….constraint imposed by……” should be “….constraint by……”,  “gain insight into” should be “gain an insight into”,  “the surrounding area's dangerous” should be “the seismic risk in the surrounding area” “……separate and joint inversions are conducted ……” should be “……the inversions constrained by single and joint data are conducted and compared……”.

Author Response

Dear Reviewer

Thank you very much for your careful review of the manuscript. Your suggestions and questions are very helpful for us to improve the quality of the article. We have made careful modifications in the text according to your suggestions. We also made a point-to-point reply. Response to Reviewer3.docx

Author Response File: Author Response.docx