Quantifying Creep on the Laohushan Fault Using Dense Continuous GNSS
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsJudging from the title of the paper, the research content of the paper is a relatively meaningful research topic. However, in the description of the paper, the following contents need additional explanation:
1. What type of equipment does the paper mainly use GNSS to accept? The article states that the usage data exceeds 2 years of installation time. How do you understand it?
2. The paper does not clearly explain the processing method of GNSS time series. Please provide additional explanation?
3. The preface of the paper states that the method of the paper was adopted because of the wonderful InSAR technology. However, there is no comparison at the end of the paper, indicating that the method of the paper is the current InSAR technology.
Author Response
Comments 1: What type of equipment does the paper mainly use GNSS to accept? The article states that the usage data exceeds 2 years of installation time. How do you understand it?
Response 1: Thanks for your comments.(1) In our study, we used Trimble NET R9 GNSS receiver, TRM159900.00 antenna, and Trimble Zephyr 3 geodetic antenna. We have provided additional visual figures, which are included in the attached materials for your review. (2)We have thoroughly reviewed the manuscript and corrected the presentation error you noted on page 4, lines 122-123. The revised statement is as follows: "With the exception of station JT04, all other stations have more than 2.5 years of observation data, ensuring the acquisition of stable and reliable results.".
Comments 2: The paper does not clearly explain the processing method of GNSS time series. Please provide additional explanation?
Response 2: Thanks for your comments. We have added a section between lines 153 and 164 on pages 4-5 of the manuscript detailing the methodology for processing GNSS short baseline time series data. Additionally, we included a time series plot of the baseline horizontal vector in the manuscript. Due to the effects of atmospheric refraction and antenna phase center errors, the vertical positioning accuracy of the GNSS observations remains lower than the horizontal accuracy. As a result, we have not applied the GNSS data to discussions of vertical deformation in this study. After obtaining the horizontal baseline time series, we projected the GNSS short-baseline horizontal vectors along directions parallel (SE102°) and perpendicular (NE12°) to the Laohushan Fault using equation (1). We have provided equation, which is included in the attached materials for your review.
Comments 3: The preface of the paper states that the method of the paper was adopted because of the wonderful InSAR technology. However, there is no comparison at the end of the paper, indicating that the method of the paper is the current InSAR technology.
Response 3: Thank you for your insightful feedback. We appreciate your observation regarding the discussion of GNSS technology in relation to InSAR methods. We have added a section between lines 338 and 377 on pages 10 through 12 of the manuscript comparing the creep rates of the Laohushan Fault obtained from both GNSS and InSAR. This addition will help to highlight the strengths and limitations of both approaches in the context of our findings.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThis study addresses the limitations of previous research on the creep behavior of the Laohushan Fault, which has largely relied on InSAR data, by incorporating high-precision GNSS observations for enhanced validation. A dense GNSS continuous observation profile, with station spacing as close as 2 km, was established across the eastern segment of the Laohushan Fault, and nearly seven years of accumulated data were collected. These data were used to calculate the time series of baseline changes across the GNSS stations and to construct a high spatial resolution horizontal crustal velocity field for the region. The results provide a comprehensive depiction of the current dynamic deformation characteristics of the Laohushan Fault in both the near-field and far-field. Based on these findings, the present-day creep rate and its temporal variation were precisely determined, along with an analysis of the depth distribution of creeping and locked segments. These results offer critical insights for further research into the fault’s mechanical behavior and for assessing regional seismic hazards. However, before accepted, it needs to be strengthened in the following ways:
1. Lines 130-131 Please specify the time of the GNSS observation.
2. Line190 Please ensure that references are formatted correctly!
3. Lines 274-275 Please ensure that references are formatted correctly!
4. Figure 3c. There is a grammatical mistake in the presentation of Figure 3, which should be stated as “The errors associated with common points used in the 200 integration of the published velocity field.”
5. Figure 6. In this paper, the Haiyuan Fault is divided into three segments. The authors should specify which segment of the Haiyuan Fault is referenced in the decomposition and projection of the GNSS velocity field.
6. Figure 7. There is a grammatical mistake in the presentation, which should be stated as “The distribution of small earthquake activity on the Laohushan fault.”
7. Please adjust the width of Table 1 to ensure that the word 'Perpendicular' is displayed on a single line.
8. I have identified some grammatical mistakes. Please check the English grammar of the full text and review the manuscript carefully.
Author Response
Comments 1: Lines 130-131 Please specify the time of the GNSS observation.
Response 1: Thanks for your comments. We have added information about the timing of the GNSS observations to lines 138-140 on page 4 of the manuscript.
Comments 2: Line190 Please ensure that references are formatted correctly!
Response 2: Thanks for your comments. We have updated the reference and kept it formatted correctly.
Comments 3: Lines 274-275 Please ensure that references are formatted correctly!
Response 3:Thanks for your comments. We have updated the reference and kept it formatted correctly.
Comments 4: Figure 3c. There is a grammatical mistake in the presentation of Figure 3, which should be stated as “The errors associated with common points used in the 200 integration of the published velocity field.”
Response 4:Thanks for your comments. We have revised the annotation of Figure 3 in the manuscript.
Comments 5: Figure 6. In this paper, the Haiyuan Fault is divided into three segments. The authors should specify which segment of the Haiyuan Fault is referenced in the decomposition and projection of the GNSS velocity field.
Response 5:Thanks for your comments. We modified Figure6 in the manuscript.
Comments 6: Figure 7. There is a grammatical mistake in the presentation, which should be stated as “The distribution of small earthquake activity on the Laohushan fault.”
Response 6:Thanks for your comments. We have revised the annotation of Figure 7 in the manuscript.
Comments 7: Please adjust the width of Table 1 to ensure that the word 'Perpendicular' is displayed on a single line.
Response 7:Thanks for your comments. We modified Table 1 in the manuscript.
Comments 8: I have identified some grammatical mistakes. Please check the English grammar of the full text and review the manuscript carefully.
Response 8: Thank you for your valuable feedback. we appreciate your thorough review of the manuscript. we hace carefully checked the English grammar throughout the entire text and make the necessary revisions to ensure clarity and accuracy.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsVery long introduction. The text in Figure 2 and Figure 5 is too small.
Author Response
Comments 1: Very long introduction. The text in Figure 2 and Figure 5 is too small.
Response 1: Thank you for your valuable feedback. We have worked on condensing the introduction to make it more concise and focused. Additionally, we have resized the text in Figures 3 and 7 to ensure better readability. Thank you very much for your insights, which will help improve the clarity of the manuscript. (Some of the additions we made to the manuscript resulted in a change in the numbering of the figures)
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThe text "Quantifying Creep on the Laohushan Fault Using Dense Continuous GNSS " is organised correctly, and all sections effectively describe the research goal established by the authors. The main goal of the text is to assess the movement of the Laohushan Fault based on the GNSS observations as an alternative to InSAR remote sensing technology.
The methodology is planned very well and represents all aspects that can be useful for such creep quantification. The results were presented well and allowed readers to assess the reality of the Laohushan movement. The final results and conclusions are valuable for the citizens of China and show the risk of living in this area.
I would like to point out the lack in the introduction section. I think there are too few details about similar measurements in other parts of the world. First of all, it could help the readers compare the methodology of measurements, and second, imagine if the creep on the Laohushan Fault is serious in the context of other similar places. So the literature review should be improved.
I also see some issues with the GNSS part. I would like to know what the permanent stations look like. How was it stabilised? What receivers were used? How the data were transferred for calculations? Was it online or a direct transfer from the receivers? The biggest doubt I have is the accuracy of the receivers. In the text, you mention movements close to several millimetres. It is crucial to mention what is the range of errors for the receivers. You cannot assume it is equal to zero. The error exists, and it is natural. The scale of error is very important in judging the obtained results.
Anyway, I think the text is perfect and worth publishing considering the matter of the subject.
Author Response
Comments 1: I would like to point out the lack in the introduction section. I think there are too few details about similar measurements in other parts of the world. First of all, it could help the readers compare the methodology of measurements, and second, imagine if the creep on the Laohushan Fault is serious in the context of other similar places. So the literature review should be improved.
Response 1: Thank you for your insightful comments. I understand the importance of providing a broader context by including similar measurements from other regions. With advancements in geodetic technology, GNSS and InSAR observations have become widely employed for characterizing fault creep deformation. However, due to the limited distribution of GNSS stations, studies focusing exclusively on fault creep motion using GNSS data remain relatively scarce. At present, GNSS-based investigations have primarily focused on the Atotsugawa Fault, the Alto Tiberina Fault, and the Dead Sea Fault. We have added the similar measurements in other parts of the world on page 2, lines 54-59.. This will help readers better contextualize the results from the Laohushan Fault.
Comments 2: I also see some issues with the GNSS part. I would like to know what the permanent stations look like. How was it stabilised? What receivers were used? How the data were transferred for calculations? Was it online or a direct transfer from the receivers? The biggest doubt I have is the accuracy of the receivers. In the text, you mention movements close to several millimetres. It is crucial to mention what is the range of errors for the receivers. You cannot assume it is equal to zero. The error exists, and it is natural. The scale of error is very important in judging the obtained results.
Response 2: Thank you for your insightful comments.(1) A permanent GNSS station refers to a long-term, fixed GNSS observation station , typically consisting of a high-precision GNSS receiver and antenna, which continuously monitors and collects data on the Earth's surface position. These stations are usually located in geologically stable areas, providing continuous, high-precision positioning information. We have provided additional visual figures, which are included in the attached materials for your review. (2) In our study, we used Trimble NET R9 GNSS receiver, TRM159900.00 antenna, and Trimble Zephyr 3 geodetic antenna. We have provided additional visual figures, which are included in the attached materials for your review. (3) The data used in this study were directly transmitted from the receiver.(4) The receiver used in this study is a geodetic-grade GNSS receiver, with horizontal accuracy better than 3 mm. This type of receiver has been widely used in monitoring crustal deformation in mainland China, yielding significant research results.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsAfter revision, the manuscript is now ready for publication.
