Brief Communication: A case study of risk assessment for facilities associated with earthquake-induced liquefaction potential in Kimhae City, South Korea&nbsp;

Jeon, Sang-Soo; Heo, Daeyang; Lee, Sang-Seung

doi:https://doi.org/10.5194/nhess-2021-287

Preprints

https://doi.org/10.5194/nhess-2021-287

Preprints

21 Oct 2021

| 21 Oct 2021

Status: this discussion paper is a preprint. It has been under review for the journal Natural Hazards and Earth System Sciences (NHESS). The manuscript was not accepted for further review after discussion.

Brief Communication: A case study of risk assessment for facilities associated with earthquake-induced liquefaction potential in Kimhae City, South Korea

Sang-Soo Jeon, Daeyang Heo, and Sang-Seung Lee

Abstract. Liquefaction causes secondary damage after earthquakes; however, liquefaction related phenomena were rarely reported until after the M_w = 5.4 November 15, 2017 Pohang earthquake in Korea. Both the M_w = 5.8 September 12, 2016 Gyeongju earthquake and M_w = 5.4 November 15, 2017 Pohang earthquake occurred in the fault zone of Yangsan City (located in the south-eastern part of Korea), and both of these earthquakes induced liquefaction. Moreover, they demonstrated that Korea is not safe against the liquefaction induced by earthquakes. In this study, estimations and calculations were performed based on the distances between the centroids of administrative districts and an epicenter located at the Yangsan Fault, the peak ground accelerations (PGAs) induced by M_w = 5.0 and 6.5 earthquakes, and a liquefaction potential index (LPI) calculated based on groundwater level and standard penetration test results from 274 locations in Kimhae City (adjacent to the Nakdong river and across the Yangsan Fault). Then, a kriging method using geographical information systems was used to evaluate the liquefaction effects on the risk levels of facilities. The results indicate that a M_w = 5.0 earthquake induces a small and low level of liquefaction, resulting in slight risk for facilities, but a M_w = 6.5 earthquake induces a large and high level of liquefaction, resulting in a severe risk for facilities.

Received: 01 Oct 2021 – Discussion started: 21 Oct 2021

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.

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Sang-Soo Jeon, Daeyang Heo, and Sang-Seung Lee

Status: closed

RC1:
'Comment on nhess-2021-287', Anonymous Referee #1, 09 Nov 2021
Review to:

Brief Communication: A case study of risk assessment for facilities associated with earthquake-induced liquefaction potential in Kimhae City, South Korea;

By: Sang-Soo Jeon, Daeyang Heo, Sang-Seung Lee

Jeon et al. evaluate severity of liquefaction in Kimhae, a city in Southern Korea, adjacent to the Nakdong river, due to a possible Mw = 5.0 and 6.5 earthquakes originated along the Yangsan Fault that crosses the city. They examine the Liquefaction Potential Index (LPI) calculated on the base on groundwater level and standard penetration tests from 274 locations in Kimhae City, and evaluate the hazard to various infrastructure facilities in the city.

This is an important investigation relevant to South Korea in general and particularly to Kimhae City. Nonetheless, in my opinion, the way the evaluation was conducted needs comprehensive revision and revaluation of the results and the conclusions.

My main comments are:

Terminology

The authors use various terms for the liquefaction potential in Kimhae City. For example, the title, heading 4.2, line 46 and elsewhere, speak about RISK; line 68 about “ground DAMAGE level”; line 52 about “estimate the HAZARDS induced by liquefaction”; line 75 about “levels of liquefaction SEVERITY”.

There is a need to clarify what is the evaluation about, and follow the terminology used in this discipline.

Methodology

Some aspects of the methodology are not clear, for example:

What were the criteria used for selecting the proper SPT data (Line 173) for LPI calculation;

What are the “Preliminary estimation” in the Flowchart (figure 1), and the criteria for ‘yes’ or ’no’ decision? Similar question refers also to the criteria used for FS in the same flowchart.

There is a need to present the soil classification used for the analysis

Due to the poor resolution of map 4, it is not possible to identify the location of SPTs points and figure out the spread of SPT points across the city area. As far as I could see and understand, there are some areas with no data. The authors need to determine the threshold density of information relevant to the analysis, exclude no data areas from the analysis, and accordingly reexamine and modify the results presented and elaborated in Chapters 4 and 5 and in the relevant figures.

I wonder why there is no presentation and discussion on the geology of the region. There are methods and procedures for identifying zones of required investigation for liquefaction susceptibility by geological screening, and it is thus possible to complement the investigation in region with no or scarce LPI data.

It would be useful to present the geology of the region and see whether the LPI results agree with the geology, and thus extrapolate the understandings for areas with no LPI data.

PGA:

The first paragraph in section ‘3.2 Attenuation relationship of PGA’ is confusing:

The text is hard to follow because there are many repetitions;

Lines 152-3 say that “Choi et al. (2005) was used in this study”, while lines 159-160 state the opposite for distance shorter than 10 km, and Table 3 (line 169) base the estimation on Jo and Baag (2003).

Please rephrase and explain what were the attenuation relationships used in this study?

The text states: (lines 114-115): ”the horizontally extended location from the centroid of Kimhae City to the closest fault is assumed to be the location of the epicenter”. However, Figures 2a shows a line diagonal to the fault line rather than normal to it. The same should be applied for the 17 sub districts (Figure 2b).

Thus there is a need to correct the distances and recalculate the expected PGAs.

Risk level

It appears that most of the facilities are distributed where LPI = 0. Is it an artifact due to lack of LPI data? May be there should be a minimum distance from a given facility to the nearest LPI data in order to except or reject the results.

Alternatively, are there zones with no or little LPI data but with geological conditions that favor liquefaction hazard? How would you define the hazard in such areas?

Results and discussion

While defining areas with very low level of liquefaction severity in an urbanized area for an earthquake (Result 1) on the base of interpolation of LPI data but no geological screening, there should be a note that zones of significant PGA amplification, artificial landfill, leakage of water and sewage systems, etc., should be excluded and treated with care.

Result 4: the authors state that “Therefore, the construction of buildings in regions with high liquefaction severity should be avoided.” This is a very strict conclusion that is not fully supported in this study. Such a recommendation should be taken by an engineer after geological screening, site specific investigation, and no way for a proper soil treatment.

Figures

There is a need to add location map of the study area and show where Kimhae City is in South Korea, the earthquake epicenters, faults and localities mentioned in the text.

The maps are hard to read (I could hardly see the location of the SPTs points and other information), mainly due to low resolution and scale. Please improve resolution of the maps, text on the maps (Figures 5ab), size of legend, explain what is shown at the background of the maps, and show the limits of the urban area at the background.

Technical comments

Line 38, Should be: “… earthquakes (Mw = 6.2, 7.1) in 2010 and 2011, respectively.”

Line 175: “inside of the dotted line” – do you mean the doted red ellipse in Figure 4?

Table 4 – please round the numbers where needed.

Line 196- what does it mean “plat area”?

Line 238, first sentence, seems to belong to the introduction?
Citation: https://doi.org/10.5194/nhess-2021-287-RC1
- AC1: 'Reply on RC1', SANG-SOO JEON, 13 Jan 2022
  
  Dear Referee,
  I am very glad to have an opportunity to revise the manuscript. The paper has been substantially modified based on the referees’ recommendations. The revised and corrected contents with respect to all referee comments are summarized and attached.
  I deeply appreciate for your concern and invaluable time for review process.
  
  Best regards,
  Sang-Soo Jeon
  
  Citation: https://doi.org/10.5194/nhess-2021-287-AC1
RC2:
'Comment on nhess-2021-287', Anonymous Referee #2, 12 Nov 2021

Manuscript Review

Manuscript Number nhess-2021-287

Title Brief Communication: A case study of risk assessment for facilities associated with earthquake-induced liquefaction potential in Kimhae City, South Korea

Authors Sang-Soo Jeon, Daeyang Heo, Sang-Seung Lee

Summary This article focuses on the assessment of earthquake-induced liquefaction hazard with reference to the City of Kimhae, in Southern Korea. Deterministic analysis is carried out with reference to two scenario earthquakes. The susceptibility of the soil deposits to liquefaction is evaluated starting from the outcomes of Standard Penetration Tests (SPT). The liquefaction hazard is mapped in terms of the widely adopted Liquefaction Potential Index (LPI). Based on such maps, earthquake-induced liquefaction hazard is extrapolated at the locations of specific critical infrastructures.

GENERAL COMMENT

In my opinion, the manuscript in the current version is not of sufficient quality to be published in a peer-reviewed journal. I feel that the manuscript could be reconsidered for publication only if major revisions are incorporated and the article carefully re-structured. Moreover, the authors are asked to address all the following:

[1] Abstract and Introduction should be significantly improved to allow the reader understanding the framework in which the topic lies, the relevance of the topic itself and the novelty of the approach proposed in the paper. It is also important to mention the advantages and also the limitations of the proposed methodology and how possible stakeholders would benefit from its application. The Title could also be more appealing.

[2] Confusion exists between the “hazard”, “severity”, “risk”, etc. terms. Please, clarify these concepts according to the international literature (e.g. on risks associated to natural disaster) across the manuscript.

[3] The state of the art within the Introduction needs to be significantly enriched by adding more references. To be honest, I am really surprised that none of the most relevant international references in the field of mapping the earthquake-induced liquefaction susceptibility and hazard are cited. Among others, I would like to mention the manual prepared in 1999 by the Technical Committee for Seismic Geotechnical Engineering (TC4) of the International Society for Soil Mechanics and Geotechnical Engineering, which suggests that the zoning of seismic-geotechnical hazards should be carried out according to three levels of detail and increasing refinement, which are named grade-1, grade-2 and grade-3. Recent relevant experiences in Europe should be also mentioned (see the Special Issue on the H2020 European Project LiqueFACT on Bulletin of Earthquake Engineering, 2021). In the manuscript, starting from a comprehensive and critical review of the literature, the novelty of the approach proposed by the Authors should be highlighted. Advantages and also the limitations of the proposed methodology should be mentioned in the Introduction and also in the Abstract.

[4] Earthquake-induced ground shaking is affected by: (i) source characteristics, (ii) propagation path, (iii) local site conditions, i.e. presence of soft soil deposits, basin structures, surface topography. Within the manuscript, any reference to the complexity of wave propagation is completely missing.

[5] The paper completely lacks specific sections to illustrate the seismo-tectonic setting and the geological framework of the area under investigation. Moreover, I would expect the building of a subsoil model starting from geological information and geotechnical data.

[6] The quality of the figures especially the maps is really poor and the meaning of the map/s showing the results should be better explained within the text.

[7] This study completely lacks of a sensitivity analysis able to address the influence of the several assumptions carried out by the Authors on the results. Uncertainty associated to the different steps is neve mentioned.

[8] The Authors adopted only Liquefaction Potential Index (LPI, originally proposed by Iwasaki et al. 1978, 1982), but more recent lumped parameters have been proposed (e.g. Liquefaction Severity Number, LSN, etc.) and widely used in the literature.

[9] Many sentences in the manuscript need to be substantiated by citing bibliographic references from the literature, e.g. available methods for assessing liquefaction potential from SPT, CPT, etc. I strongly recommend to adopt more then one method available for SPT data.

[10] All the steps of the methodology are not clear in the current version of the flowchart (Figure 1), that needs to be improved, in my opinion. Please, check carefully any missing arrows and consequent step/s.

[11] Could you try to validate the map by overlapping the location of manifestations of liquefaction?

[12] I strongly recommend to avoid to extrapolate the liquefaction hazard from such kind of maps at the locations of specific critical infrastructures. In case of specific structures/infrastructures, specific analysis is needed starting from an in-deep ground characterization of soil deposits at the site of interest.

[13] In the Conclusions, limitations and weakness points of the proposed methodology and of the presented application should be discussed in details. Concluding remarks are not fully supported in the study (see also Comment [11]). Can this methodology be applied to other areas? How? Who will be benefit from this type of maps?

[14] The manuscript should be read carefully for English language.

[15] Please, read carefully the paper for typing errors.

[16] Please, define the symbols, acronyms, etc. the first time you used them in the manuscript and then be consistent in the remaining text.

[17] With reference to the earthquake magnitude of the mentioned seismic events, please provide the source and add the references.

Citation: https://doi.org/10.5194/nhess-2021-287-RC2
- AC2: 'Reply on RC2', SANG-SOO JEON, 13 Jan 2022
  
  Dear Referee,
  I am very glad to have an opportunity to revise the manuscript. The paper has been substantially modified based on the referees’ recommendations. The revised and corrected contents with respect to all referee comments are summarized and attached.
  I deeply appreciate for your concern and invaluable time for review process.
  
  Best regards,
  Sang-Soo Jeon
  
  Citation: https://doi.org/10.5194/nhess-2021-287-AC2
RC3:
'Comment on nhess-2021-287', Anonymous Referee #3, 28 Nov 2021
General comments

The paper describes a study where the liquefaction potential of soils in the Kimhae City, South Korea, is assessed concerning two seismic scenarios of moment magnitude 5.0 and 6.5, respectively. The paper undoubtedly addressed relevant scientific and technical questions within the scope of NHESS, because it presents new data and investigates a new case study. Even though scientific significance can be detected in the current version of the manuscript, the scientific and presentation quality needs a wide and accurate revision. The adopted technical approach based on the LPI index is well-established in the current state of practice, but a systematic literature review of the most recent and innovative methods for soil liquefaction assessment is completely missing. In addition, the background for the considered case study needs to be integrated with the findings of previous studies, if existing, or the absence of previous works should be likewise highlighted. This is relevant for understanding the importance and the scope of the proposed study.

The criticisms that should be addressed in the revised paper are further detailed in the next section “Specific comments”, while the main “technical corrections” are also summarized in the next. Finally, the size, quality, and readability of each figure are not adequate to the type and quantity of data presented and an extensive revision is required.

Specific comments

Line 14-26: The abstract does not provide a concise, complete, and unambiguous summary of the work done and the results obtained. In particular, the 2016 Gyeongju earthquake mentioned in the abstract is not mentioned in the ensuing paper. Please, revise the abstract so that is going to reflect the paper contents;

Line 35: Since the study is going to be published in an international journal, a figure introducing the study area in the geographical context of South Korea will be greatly appreciated;

Lines 36-38: In the paper, the most recent seismic events that induced liquefaction are not mentioned, e.g., 2018 Palu, Indonesia earthquake; 2020 Petrinja, Croatia earthquake;

Line 46: The adopted LPI index has multiple drawbacks, widely known in the literature. At least a review of the most recent indexes should be included in the revised paper (e.g., (Sonmez 2003; van Ballegooy et al. 2014; Chiaradonna et al. 2020);

Line 85-92: The description of the safety factor calculation is too approximate. The results are largely affected by the results (see Ramos et al. 2021 for instance), so the empirical method adopted for the calculation is not a secondary piece of information, and it needs to be specified;

The English language can be improved (e.g., line 15);

Technical corrections

Line 3: “potential” can be omitted;

Line 35: Pohang EQ is not introduced in the text. Please, add details (e.g., magnitude, date, epicenter) about this seismic event at the first mention in the body text;

Line 49: FS is not defined;

Figure 1. The flow chart is not properly discussed in the text. In particular, some parameters reported in the flow chart “S_C, S_D, S_E, S_F” remain undefined. Please, clarify this point.

Figure 2b. The centroids of the administrative areas are not visible. Please, move the centroid layer above the shaded area of study;

Table 2. The administrative districts are listed in Table but cannot be visualized in Figure 2. Please, rearrange the map in Figure 2a so that the name and boundary of each district can be identified;

Figure 3. Labels in the legend cannot be read. Please, increase the figure resolution. However, the law by Choi et al. (2005) seems not reported, differently from what is said in the text. Please, revise accordingly;

Table 3. Numbers in table 3 are not readable. Please, revise;

Figure 4. It is too small and the legend is unreadable. Please, enlarge the figure and increase the resolution;

Section 4. Line 184: The current section consists of one sentence and one table. Too short to be considered a stand-alone paragraph of the paper. Please, revise adding a detailed description of the facilities or moving the table elsewhere.

Figures 6 are too small and the facilities are unreadable in many cases. Please, revise.
Citation: https://doi.org/10.5194/nhess-2021-287-RC3
- AC3: 'Reply on RC3', SANG-SOO JEON, 13 Jan 2022
  
  Dear Referee,
  I am very glad to have an opportunity to revise the manuscript. The paper has been substantially modified based on the referees’ recommendations. The revised and corrected contents with respect to all referee comments are summarized and attached.
  I deeply appreciate for your concern and invaluable time for review process.
  
  Best regards,
  Sang-Soo Jeon
  
  Citation: https://doi.org/10.5194/nhess-2021-287-AC3

Status: closed

RC1:
'Comment on nhess-2021-287', Anonymous Referee #1, 09 Nov 2021
Review to:

Brief Communication: A case study of risk assessment for facilities associated with earthquake-induced liquefaction potential in Kimhae City, South Korea;

By: Sang-Soo Jeon, Daeyang Heo, Sang-Seung Lee

Jeon et al. evaluate severity of liquefaction in Kimhae, a city in Southern Korea, adjacent to the Nakdong river, due to a possible Mw = 5.0 and 6.5 earthquakes originated along the Yangsan Fault that crosses the city. They examine the Liquefaction Potential Index (LPI) calculated on the base on groundwater level and standard penetration tests from 274 locations in Kimhae City, and evaluate the hazard to various infrastructure facilities in the city.

This is an important investigation relevant to South Korea in general and particularly to Kimhae City. Nonetheless, in my opinion, the way the evaluation was conducted needs comprehensive revision and revaluation of the results and the conclusions.

My main comments are:

Terminology

The authors use various terms for the liquefaction potential in Kimhae City. For example, the title, heading 4.2, line 46 and elsewhere, speak about RISK; line 68 about “ground DAMAGE level”; line 52 about “estimate the HAZARDS induced by liquefaction”; line 75 about “levels of liquefaction SEVERITY”.

There is a need to clarify what is the evaluation about, and follow the terminology used in this discipline.

Methodology

Some aspects of the methodology are not clear, for example:

What were the criteria used for selecting the proper SPT data (Line 173) for LPI calculation;

What are the “Preliminary estimation” in the Flowchart (figure 1), and the criteria for ‘yes’ or ’no’ decision? Similar question refers also to the criteria used for FS in the same flowchart.

There is a need to present the soil classification used for the analysis

Due to the poor resolution of map 4, it is not possible to identify the location of SPTs points and figure out the spread of SPT points across the city area. As far as I could see and understand, there are some areas with no data. The authors need to determine the threshold density of information relevant to the analysis, exclude no data areas from the analysis, and accordingly reexamine and modify the results presented and elaborated in Chapters 4 and 5 and in the relevant figures.

I wonder why there is no presentation and discussion on the geology of the region. There are methods and procedures for identifying zones of required investigation for liquefaction susceptibility by geological screening, and it is thus possible to complement the investigation in region with no or scarce LPI data.

It would be useful to present the geology of the region and see whether the LPI results agree with the geology, and thus extrapolate the understandings for areas with no LPI data.

PGA:

The first paragraph in section ‘3.2 Attenuation relationship of PGA’ is confusing:

The text is hard to follow because there are many repetitions;

Lines 152-3 say that “Choi et al. (2005) was used in this study”, while lines 159-160 state the opposite for distance shorter than 10 km, and Table 3 (line 169) base the estimation on Jo and Baag (2003).

Please rephrase and explain what were the attenuation relationships used in this study?

The text states: (lines 114-115): ”the horizontally extended location from the centroid of Kimhae City to the closest fault is assumed to be the location of the epicenter”. However, Figures 2a shows a line diagonal to the fault line rather than normal to it. The same should be applied for the 17 sub districts (Figure 2b).

Thus there is a need to correct the distances and recalculate the expected PGAs.

Risk level

It appears that most of the facilities are distributed where LPI = 0. Is it an artifact due to lack of LPI data? May be there should be a minimum distance from a given facility to the nearest LPI data in order to except or reject the results.

Alternatively, are there zones with no or little LPI data but with geological conditions that favor liquefaction hazard? How would you define the hazard in such areas?

Results and discussion

While defining areas with very low level of liquefaction severity in an urbanized area for an earthquake (Result 1) on the base of interpolation of LPI data but no geological screening, there should be a note that zones of significant PGA amplification, artificial landfill, leakage of water and sewage systems, etc., should be excluded and treated with care.

Result 4: the authors state that “Therefore, the construction of buildings in regions with high liquefaction severity should be avoided.” This is a very strict conclusion that is not fully supported in this study. Such a recommendation should be taken by an engineer after geological screening, site specific investigation, and no way for a proper soil treatment.

Figures

There is a need to add location map of the study area and show where Kimhae City is in South Korea, the earthquake epicenters, faults and localities mentioned in the text.

The maps are hard to read (I could hardly see the location of the SPTs points and other information), mainly due to low resolution and scale. Please improve resolution of the maps, text on the maps (Figures 5ab), size of legend, explain what is shown at the background of the maps, and show the limits of the urban area at the background.

Technical comments

Line 38, Should be: “… earthquakes (Mw = 6.2, 7.1) in 2010 and 2011, respectively.”

Line 175: “inside of the dotted line” – do you mean the doted red ellipse in Figure 4?

Table 4 – please round the numbers where needed.

Line 196- what does it mean “plat area”?

Line 238, first sentence, seems to belong to the introduction?
Citation: https://doi.org/10.5194/nhess-2021-287-RC1
- AC1: 'Reply on RC1', SANG-SOO JEON, 13 Jan 2022
  
  Dear Referee,
  I am very glad to have an opportunity to revise the manuscript. The paper has been substantially modified based on the referees’ recommendations. The revised and corrected contents with respect to all referee comments are summarized and attached.
  I deeply appreciate for your concern and invaluable time for review process.
  
  Best regards,
  Sang-Soo Jeon
  
  Citation: https://doi.org/10.5194/nhess-2021-287-AC1
RC2:
'Comment on nhess-2021-287', Anonymous Referee #2, 12 Nov 2021

Manuscript Review

Manuscript Number nhess-2021-287

Title Brief Communication: A case study of risk assessment for facilities associated with earthquake-induced liquefaction potential in Kimhae City, South Korea

Authors Sang-Soo Jeon, Daeyang Heo, Sang-Seung Lee

Summary This article focuses on the assessment of earthquake-induced liquefaction hazard with reference to the City of Kimhae, in Southern Korea. Deterministic analysis is carried out with reference to two scenario earthquakes. The susceptibility of the soil deposits to liquefaction is evaluated starting from the outcomes of Standard Penetration Tests (SPT). The liquefaction hazard is mapped in terms of the widely adopted Liquefaction Potential Index (LPI). Based on such maps, earthquake-induced liquefaction hazard is extrapolated at the locations of specific critical infrastructures.

GENERAL COMMENT

In my opinion, the manuscript in the current version is not of sufficient quality to be published in a peer-reviewed journal. I feel that the manuscript could be reconsidered for publication only if major revisions are incorporated and the article carefully re-structured. Moreover, the authors are asked to address all the following:

[1] Abstract and Introduction should be significantly improved to allow the reader understanding the framework in which the topic lies, the relevance of the topic itself and the novelty of the approach proposed in the paper. It is also important to mention the advantages and also the limitations of the proposed methodology and how possible stakeholders would benefit from its application. The Title could also be more appealing.

[2] Confusion exists between the “hazard”, “severity”, “risk”, etc. terms. Please, clarify these concepts according to the international literature (e.g. on risks associated to natural disaster) across the manuscript.

[3] The state of the art within the Introduction needs to be significantly enriched by adding more references. To be honest, I am really surprised that none of the most relevant international references in the field of mapping the earthquake-induced liquefaction susceptibility and hazard are cited. Among others, I would like to mention the manual prepared in 1999 by the Technical Committee for Seismic Geotechnical Engineering (TC4) of the International Society for Soil Mechanics and Geotechnical Engineering, which suggests that the zoning of seismic-geotechnical hazards should be carried out according to three levels of detail and increasing refinement, which are named grade-1, grade-2 and grade-3. Recent relevant experiences in Europe should be also mentioned (see the Special Issue on the H2020 European Project LiqueFACT on Bulletin of Earthquake Engineering, 2021). In the manuscript, starting from a comprehensive and critical review of the literature, the novelty of the approach proposed by the Authors should be highlighted. Advantages and also the limitations of the proposed methodology should be mentioned in the Introduction and also in the Abstract.

[4] Earthquake-induced ground shaking is affected by: (i) source characteristics, (ii) propagation path, (iii) local site conditions, i.e. presence of soft soil deposits, basin structures, surface topography. Within the manuscript, any reference to the complexity of wave propagation is completely missing.

[5] The paper completely lacks specific sections to illustrate the seismo-tectonic setting and the geological framework of the area under investigation. Moreover, I would expect the building of a subsoil model starting from geological information and geotechnical data.

[6] The quality of the figures especially the maps is really poor and the meaning of the map/s showing the results should be better explained within the text.

[7] This study completely lacks of a sensitivity analysis able to address the influence of the several assumptions carried out by the Authors on the results. Uncertainty associated to the different steps is neve mentioned.

[8] The Authors adopted only Liquefaction Potential Index (LPI, originally proposed by Iwasaki et al. 1978, 1982), but more recent lumped parameters have been proposed (e.g. Liquefaction Severity Number, LSN, etc.) and widely used in the literature.

[9] Many sentences in the manuscript need to be substantiated by citing bibliographic references from the literature, e.g. available methods for assessing liquefaction potential from SPT, CPT, etc. I strongly recommend to adopt more then one method available for SPT data.

[10] All the steps of the methodology are not clear in the current version of the flowchart (Figure 1), that needs to be improved, in my opinion. Please, check carefully any missing arrows and consequent step/s.

[11] Could you try to validate the map by overlapping the location of manifestations of liquefaction?

[12] I strongly recommend to avoid to extrapolate the liquefaction hazard from such kind of maps at the locations of specific critical infrastructures. In case of specific structures/infrastructures, specific analysis is needed starting from an in-deep ground characterization of soil deposits at the site of interest.

[13] In the Conclusions, limitations and weakness points of the proposed methodology and of the presented application should be discussed in details. Concluding remarks are not fully supported in the study (see also Comment [11]). Can this methodology be applied to other areas? How? Who will be benefit from this type of maps?

[14] The manuscript should be read carefully for English language.

[15] Please, read carefully the paper for typing errors.

[16] Please, define the symbols, acronyms, etc. the first time you used them in the manuscript and then be consistent in the remaining text.

[17] With reference to the earthquake magnitude of the mentioned seismic events, please provide the source and add the references.

Citation: https://doi.org/10.5194/nhess-2021-287-RC2
- AC2: 'Reply on RC2', SANG-SOO JEON, 13 Jan 2022
  
  Dear Referee,
  I am very glad to have an opportunity to revise the manuscript. The paper has been substantially modified based on the referees’ recommendations. The revised and corrected contents with respect to all referee comments are summarized and attached.
  I deeply appreciate for your concern and invaluable time for review process.
  
  Best regards,
  Sang-Soo Jeon
  
  Citation: https://doi.org/10.5194/nhess-2021-287-AC2
RC3:
'Comment on nhess-2021-287', Anonymous Referee #3, 28 Nov 2021
General comments

The paper describes a study where the liquefaction potential of soils in the Kimhae City, South Korea, is assessed concerning two seismic scenarios of moment magnitude 5.0 and 6.5, respectively. The paper undoubtedly addressed relevant scientific and technical questions within the scope of NHESS, because it presents new data and investigates a new case study. Even though scientific significance can be detected in the current version of the manuscript, the scientific and presentation quality needs a wide and accurate revision. The adopted technical approach based on the LPI index is well-established in the current state of practice, but a systematic literature review of the most recent and innovative methods for soil liquefaction assessment is completely missing. In addition, the background for the considered case study needs to be integrated with the findings of previous studies, if existing, or the absence of previous works should be likewise highlighted. This is relevant for understanding the importance and the scope of the proposed study.

The criticisms that should be addressed in the revised paper are further detailed in the next section “Specific comments”, while the main “technical corrections” are also summarized in the next. Finally, the size, quality, and readability of each figure are not adequate to the type and quantity of data presented and an extensive revision is required.

Specific comments

Line 14-26: The abstract does not provide a concise, complete, and unambiguous summary of the work done and the results obtained. In particular, the 2016 Gyeongju earthquake mentioned in the abstract is not mentioned in the ensuing paper. Please, revise the abstract so that is going to reflect the paper contents;

Line 35: Since the study is going to be published in an international journal, a figure introducing the study area in the geographical context of South Korea will be greatly appreciated;

Lines 36-38: In the paper, the most recent seismic events that induced liquefaction are not mentioned, e.g., 2018 Palu, Indonesia earthquake; 2020 Petrinja, Croatia earthquake;

Line 46: The adopted LPI index has multiple drawbacks, widely known in the literature. At least a review of the most recent indexes should be included in the revised paper (e.g., (Sonmez 2003; van Ballegooy et al. 2014; Chiaradonna et al. 2020);

Line 85-92: The description of the safety factor calculation is too approximate. The results are largely affected by the results (see Ramos et al. 2021 for instance), so the empirical method adopted for the calculation is not a secondary piece of information, and it needs to be specified;

The English language can be improved (e.g., line 15);

Technical corrections

Line 3: “potential” can be omitted;

Line 35: Pohang EQ is not introduced in the text. Please, add details (e.g., magnitude, date, epicenter) about this seismic event at the first mention in the body text;

Line 49: FS is not defined;

Figure 1. The flow chart is not properly discussed in the text. In particular, some parameters reported in the flow chart “S_C, S_D, S_E, S_F” remain undefined. Please, clarify this point.

Figure 2b. The centroids of the administrative areas are not visible. Please, move the centroid layer above the shaded area of study;

Table 2. The administrative districts are listed in Table but cannot be visualized in Figure 2. Please, rearrange the map in Figure 2a so that the name and boundary of each district can be identified;

Figure 3. Labels in the legend cannot be read. Please, increase the figure resolution. However, the law by Choi et al. (2005) seems not reported, differently from what is said in the text. Please, revise accordingly;

Table 3. Numbers in table 3 are not readable. Please, revise;

Figure 4. It is too small and the legend is unreadable. Please, enlarge the figure and increase the resolution;

Section 4. Line 184: The current section consists of one sentence and one table. Too short to be considered a stand-alone paragraph of the paper. Please, revise adding a detailed description of the facilities or moving the table elsewhere.

Figures 6 are too small and the facilities are unreadable in many cases. Please, revise.
Citation: https://doi.org/10.5194/nhess-2021-287-RC3
- AC3: 'Reply on RC3', SANG-SOO JEON, 13 Jan 2022
  
  Dear Referee,
  I am very glad to have an opportunity to revise the manuscript. The paper has been substantially modified based on the referees’ recommendations. The revised and corrected contents with respect to all referee comments are summarized and attached.
  I deeply appreciate for your concern and invaluable time for review process.
  
  Best regards,
  Sang-Soo Jeon
  
  Citation: https://doi.org/10.5194/nhess-2021-287-AC3

Sang-Soo Jeon, Daeyang Heo, and Sang-Seung Lee

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Short summary

Liquefaction causes secondary damage after earthquakes; however, liquefaction related phenomena were rarely reported in Korea. They demonstrated that Korea is not safe against the liquefaction induced by earthquakes. The results indicate that a M_w = 5.0 earthquake induces a small and low level of liquefaction, resulting in slight risk for facilities, but a M_w = 6.5 earthquake induces a large and high level of liquefaction, resulting in a severe risk for facilities.


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