Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors,

This manuscript is interesting. However, there are major flaws and I have to regret to reject it. Below is a list of some of the reasons. I suggest the authors to revise the manuscript and resubmit as a Review.

1. The main concern is related to the references: the manuscript has only 12 references, and among them, 6 are self- citation. Moreover, this manuscript is very similar to Ref [1], and therefore authors should be aware of repetition of content among similar research.
2. I could not access Ref [3].
3. The objectives are not clear.
4. The numerical model setting is not very well explained, and the lack of high quality bathymetry and topography data make the tsunami numerical model results for the inundation irrelevant.
5. The contribution and update of this manuscript is not clear when compared to Ref [1] and the Experts’ Meetings on tsunami sources from Tonga-Kermadec and Colombia-Ecuador subduction zones Ref [8,9]. The authors used different tsunami source scenarios in Ref [1] from Ref [8,9] but no justification is presented (tectonic setting, recent earthquakes, etc).
6. The results cannot be validated because of poor quality images. Particularly in urban areas the numerical model results are not accurate enough to conduct a realistic tsunami evacuation maps and the statelite images have poor quality.
7. The authors only presented the inundation maps at Potrero and Quepos. The results obtained in the other places should also be presented. Other results are presented in Puntarenas, so it is very difficult to validate the results.

Author Response

Reviewer 1

Dear authors,

This manuscript is interesting. However, there are major flaws and I have to regret to reject it. Below is a list of some of the reasons. I suggest the authors to revise the manuscript and resubmit as a Review.

1. The main concern is related to the references: the manuscript has only 12 references, and among them, 6 are self- citation. Moreover, this manuscript is very similar to Ref [1], and therefore authors should be aware of repetition of content among similar research.

Several references were added regarding methodologies for Tsunami Hazard Assessments, Evacuation Maps and historical events.

We performed several changes along the manuscript to clarify that this is not a repetition of Ref.[1] rather an update.

 

1. I could not access Ref [3].

Ref [3] is a book (in Spanish) that is available to purchase online: https://www.euna.una.ac.cr/index.php/EUNA/catalog/book/330

 

1. The objectives are not clear.

The last paragraph of the Introduction was changed to:

 

Here, we model the sources from the mentioned Experts Meetings with the objective to update and reassess the results of the Tsunami Hazard Assessment performed in [1]. These scenarios are important considering the higher impact for Costa Rica of tsunamis originated at those trenches. The scenarios proposed by the experts have either lower or higher magnitude than the scenarios employed in [1] and a stronger seismological background, and in the case of the latter, they have more precise faulting parameters than ComMIT unit sources, which play an important role for regional and local sources. Consequently, these scenarios overrule the Tonga-Kermadec and Colombia-Ecuador scenarios previously considered, requiring the update of Tsunami Evacuation Maps, Plans and Procedures, by performing numerical modeling.

 

 

1. The numerical model setting is not very well explained, and the lack of high-quality bathymetry and topography data make the tsunami numerical model results for the inundation irrelevant.

The numerical model setting was clarified, including a new Table. Also, the Model Sites were explained more extensively: one model site is defined as low-resolution to analyze tsunami maximum heights at 20m-depth and the other 13 model sites have high-resolution bathymetry that allows to perform tsunami inundation modeling. The source of topography and bathymetry was indicated for each model site in Table 1.

 

1. The contribution and update of this manuscript is not clear when compared to Ref [1] and the Experts’ Meetings on tsunami sources from Tonga-Kermadec and Colombia-Ecuador subduction zones Ref [8,9]. The authors used different tsunami source scenarios in Ref [1] from Ref [8,9] but no justification is presented (tectonic setting, recent earthquakes, etc).

 

The justification of the scenarios employed (different to the ones employed in Ref. 1) is that they are included in IOC/UNESCO reports of the meetings of experts on seismotectonic for each subduction zone, held during the review of Ref.1. The details on tectonic setting, etc., is beyond of the scope of this paper and it’s included in the Reports of the Meetings. Still, several sentences in this subject were added to Introduction, along with a few references.

 

1. The results cannot be validated because of poor quality images. Particularly in urban areas the numerical model results are not accurate enough to conduct a realistic tsunami evacuation maps and the satellite images have poor quality.

Done

 

1. The authors only presented the inundation maps at Potrero and Quepos. The results obtained in the other places should also be presented.  

Pending on Supplementary Material, as one computer crashing.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript “Numerical modeling for Costa Rica of tsunamis originated at Tonga-Kermadec and Colombia-Ecuador Subduction Zones” reassesses the tsunami hazard on selected sites of Costa Rica using numerical simulations and adapted source parameters.

General Remarks:

The authors should clarify the model: How are the source parameters generated, how is the wave propagation computed, what is the grid resolution, which topography is used, is friction considered etc.

For the manuscript, it would be crucial to better clarify what the “expert scenarios” are based on. The differences in the earthquake magnitudes are big (especially because the magnitudes are already Mw >8/ >9). Are the scenarios based on research/general seismicity/etc.? How do you estimate the likelihood of their occurrence? Please also state if the inundation area is based on the model output or on the max. flow depth and the corresponding contour lines/topography. For the inundation, especially for risk assessment, it is crucial to consider parameters such as the wavelength, friction, backflow, and the tsunami as a wave train not only as a solitary wave. Even though the wave heights/flow depth can be smaller, depending on the local topography and the wave length, the water can pile up and reach farther inland/uphill.

Since the overall purpose of the study is the reassessment of the tsunami hazard and an adaptation of the evacuation procedures, an underestimation of the inundation area from the distant sources and the usage of their worst-case-scenarios should always lead to an adaptation of the procedures (even though they are not major as stated by the authors). I do not think that simplified procedures for regional scenarios should be implemented as there might be confusion in the population on how to act in which case.

In general, the manuscript also requires language revisions. The study could be substantially improved if more relevant literature would be reviewed (the whole study is based on 12 references with 5 of them being self-citations).

 

Minor Remarks:

• Tsunami heights should be replaced with tsunami wave height
• Lines 38-40: Check language.
• Lines 109-111: Based on the model, the tsunami arrived after 2:20 hours and had a maximum wave height of 43 cm.
• Figure 6: Please add Potrero to the map.
• Table 1: Please add the abbreviations used for each scenario in the text (i.e. TK21).
• Table 1/Fig. 2a/Text: The naming of the sections is confusing (A-G not in order, i.e. North to South, plus the numbering of runs with a different order makes it hard to follow). Additionally, same names but different scenarios/sections were used for the previous study which are compared to the new results. Keeping up with the scenarios is only possible when constantly checking Figure 2 and Table 1. Please consider similar naming for both studies (e.g. implementing TK4a/b for changes in the sections or simply add oTK1-6 to Fig. 2b). Alternatively, choose different naming for the new runs which makes it easy to differentiate.
• Figure 9+10: Please indicate in the caption what the green, pink, and orange rectangles (below subfigure a) show.
• Line 314: Insert reference correctly.
• Line 347: “The latter”
• Line 411: Check formatting.
• Page 18-20/Figure 11: Delete the repeating figures, check formatting, and figure caption.
• Line 434: Check formatting.
• Page 21-22/Figure 12: Delete the repeating figures, check formatting, and figure caption.

Author Response

Reviewer 2

The manuscript “Numerical modeling for Costa Rica of tsunamis originated at Tonga-Kermadec and Colombia-Ecuador Subduction Zones” reassesses the tsunami hazard on selected sites of Costa Rica using numerical simulations and adapted source parameters.

General Remarks:

The authors should clarify the model: How are the source parameters generated, how is the wave propagation computed, what is the grid resolution, which topography is used, is friction considered etc.

The numerical model setting was clarified. Also, the Model Sites were explained more extensively: one model site is defined as low-resolution to analyze tsunami maximum heights at 20m-depth and the other 13 model sites have high-resolution bathymetry that allows to perform tsunami inundation modeling. The source of topography and bathymetry was indicated for each model site in Table 1.

For the manuscript, it would be crucial to better clarify what the “expert scenarios” are based on. The differences in the earthquake magnitudes are big (especially because the magnitudes are already Mw >8/ >9). Are the scenarios based on research/general seismicity/etc.? How do you estimate the likelihood of their occurrence?

These scenarios are based on tectonic data and the expertise of the participants in the Experts Meeting on the state-of-the-science at the regions. The discussion on the scenarios’ generation is beyond the scope of this paper and it’s available at the Meeting’s Reports. Still, several sentences were added to Introduction, along with a few references.

About the likelihood of occurrence, we don’t have the data nor the knowledge to estimate it, but it’s discussed in the Meeting’s Reports, and we included it in Table 2.

Please also state if the inundation area is based on the model output or on the max. flow depth and the corresponding contour lines/topography. For the inundation, especially for risk assessment, it is crucial to consider parameters such as the wavelength, friction, backflow, and the tsunami as a wave train not only as a solitary wave. Even though the wave heights/flow depth can be smaller, depending on the local topography and the wavelength, the water can pile up and reach farther inland/uphill.

For the Model Sites 2-14 the inundation areas were defined as the output of inundation modeling of the respective scenario or by the superposition of the results of the inundation modeling of all the scenarios considered here. There, tsunami inundation modeling was performed for 10 hours to capture the mentioned effects: please see subsection 4.1 on Wave evolution.

However, for other locations along the Costa Rica Pacific coast no having high-resolution bathymetric data, the bathtub approach was employed to define the inundation area for the tsunami evacuation maps. To define the fixed height, we used the maximum tsunami height obtained from the Low-Resolution Model Site (Model Site 1) at 20m-depth offshore of each location. These locations were not discussed in this study.

This was clarified in the manuscript.

Since the overall purpose of the study is the reassessment of the tsunami hazard and an adaptation of the evacuation procedures, an underestimation of the inundation area from the distant sources and the usage of their worst-case-scenarios should always lead to an adaptation of the procedures (even though they are not major as stated by the authors). I do not think that simplified procedures for regional scenarios should be implemented as there might be confusion in the population on how to act in which case.

The adaptation of procedures for regional scenarios was done only for emergency committees and not for the public.

In general, the manuscript also requires language revisions. The study could be substantially improved if more relevant literature would be reviewed (the whole study is based on 12 references with 5 of them being self-citations).

Several references were added related to methodologies employed in Hazard Assessment, defining inundation areas, historical events and sources definition.

Minor Remarks:

• Tsunami heights should be replaced with tsunami wave height

Done

• Lines 38-40: Check language.

Done

• Lines 109-111: Based on the model, the tsunami arrived after 2:20 hours and had a maximum wave height of 43 cm.

Corrected

• Figure 6: Please add Potrero to the map.

Done

• Table 1: Please add the abbreviations used for each scenario in the text (i.e. TK21).

Done, but now it’s Table 2.

• Table 1/Fig. 2a/Text: The naming of the sections is confusing (A-G not in order, i.e. North to South, plus the numbering of runs with a different order makes it hard to follow).

We agree, but the sections’ names were defined at the Experts Meeting and are the names in the respective Report, thus we prefer not to change them. The same for the scenarios numbering: we keep the numbers given in the Meetings’ Reports.

• Additionally, same names but different scenarios/sections were used for the previous study which are compared to the new results. Keeping up with the scenarios is only possible when constantly checking Figure 2 and Table 1. Please consider similar naming for both studies (e.g. implementing TK4a/b for changes in the sections or simply add oTK1-6 to Fig. 2b). Alternatively, choose different naming for the new runs which makes it easy to differentiate.

The name of the new runs was changed to ETK, instead of TK, to facilitate the differentiation with the older runs.

In Figure 2b the “o” was added to the names of the older runs.

• Figure 9+10: Please indicate in the caption what the green, pink, and orange rectangles (below subfigure a) show.

The following text was added to the figures caption:

Purple and green lines show the subsections for which the tsunami waves persisted for longer times compared to neighboring subsections. The orange line shows the mouth of Nicoya Gulf where tsunami waves lasted the most.

• Line 314: Insert reference correctly.

Corrected

• Line 347: “The latter

Corrected

• Line 411: Check formatting.

Corrected

• Page 18-20/Figure 11: Delete the repeating figures, check formatting, and figure caption.

Done. This was an error of the journal platform when exporting to PDF

• Line 434: Check formatting.

Corrected

• Page 21-22/Figure 12: Delete the repeating figures, check formatting, and figure caption.

Done. This was an error of the journal platform when exporting to PDF

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript of Chacón-Barrantes et al. models the propagation of tsunami scenarios to Costa Rica and their inundation for selected sites. It highlights the need for updated evacuation plans and regular tsunami drills, especially given the short arrival times from nearby sources. As a researcher working on tsunami warning, I believe this manuscript is very important to tsunami research.

 

First, I acknowledge that tsunamis generated from the Tonga-Kermadec and Colombia-Ecuador subduction zones produce the highest wave heights in Costa Rica. However, the magnitude of the earthquakes is also a crucial factor. This aspect is insufficiently discussed by the authors, and I would like to see a clear specification of the magnitudes of the far-field earthquakes.

 

Second, regarding the Tonga-Kermadec Subduction Zone, the following paper could be cited: https://doi.org/10.5194/nhess-22-1073-2022

In addition, I believe the 2022 tsunami event should be distinguished from the other events because it was not a seismogenic tsunami. I also hope the authors can explain the simulation method used, as it differs from the others.

 

Third, in the tsunami simulation, what type of motion equations were used? Were dispersion, convection, and friction considered? Could the authors provide a detailed explanation?

 

Fourth, the duration of the tsunami was considered for various locations (e.g., Fig. 10). I believe the analysis should incorporate the local characteristic periods. If the characteristic period of the topography matches the intrinsic period of the tsunami, resonance will occur, significantly prolonging the duration and amplifying the amplitude.

 

Finally, at the end of the article, I hope the authors can discuss tsunami early warning, as it is particularly meaningful for tsunami disaster prevention in communities.

 

Please consider my comments during the revision. Good luck!

Author Response

Reviewer 3

The manuscript of Chacón-Barrantes et al. models the propagation of tsunami scenarios to Costa Rica and their inundation for selected sites. It highlights the need for updated evacuation plans and regular tsunami drills, especially given the short arrival times from nearby sources. As a researcher working on tsunami warning, I believe this manuscript is very important to tsunami research.

First, I acknowledge that tsunamis generated from the Tonga-Kermadec and Colombia-Ecuador subduction zones produce the highest wave heights in Costa Rica. However, the magnitude of the earthquakes is also a crucial factor. This aspect is insufficiently discussed by the authors, and I would like to see a clear specification of the magnitudes of the far-field earthquakes.

These scenarios are based on tectonic data and the expertise of the participants in the Experts Meeting on the state-of-the-science at the regions. The discussion on the scenarios’ magnitude is beyond the scope of this paper and it’s available at the Meeting’s Reports. Still, several sentences in this subject were added to Introduction, along with a few references.

Second, regarding the Tonga-Kermadec Subduction Zone, the following paper could be cited: https://doi.org/10.5194/nhess-22-1073-2022

Done

In addition, I believe the 2022 tsunami event should be distinguished from the other events because it was not a seismogenic tsunami. I also hope the authors can explain the simulation method used, as it differs from the others.

The 2022 tsunami event was not modeled in this study, please note that Figure 4d and e does not have the bold red line of model results included in Figure 4a, b and c. The authors currently don’t have the capability to model non-tectonic tsunamis. In the Introduction is stated that the 2022 tsunami was caused by a volcanic eruption. It was included here because the larger tsunami heights observed in Costa Rica were originated after the Proudmann resonance at Tonga Trench, being the reason for having noticeable effects at the Central and South American coasts.

Third, in the tsunami simulation, what type of motion equations were used? Were dispersion, convection, and friction considered? Could the authors provide a detailed explanation?

This was included in the section 2.1 Numerical Model Setup. Also were included references to the model validation and verification report and the benchmarks employed.

Fourth, the duration of the tsunami was considered for various locations (e.g., Fig. 10). I believe the analysis should incorporate the local characteristic periods. If the characteristic period of the topography matches the intrinsic period of the tsunami, resonance will occur, significantly prolonging the duration and amplifying the amplitude.

We respectfully disagree with this as it is not related to the scope of the paper. We are not analyzing a real tsunami event, we are modeling worst-case-scenarios, which are simplification of what could be real tsunami scenarios.

On the other hand, obtaining the local characteristic periods of the 14 locations for which inundation was modeled would imply a significant amount of additional work and would generate a large amount of information, enough to write a separate paper; and again, it is not the scope of the paper.

Finally, at the end of the article, I hope the authors can discuss tsunami early warning, as it is particularly meaningful for tsunami disaster prevention in communities.

A new subsection was added: 4.5 Implications for Costa Rica tsunami warning system

Please consider my comments during the revision. Good luck!

 

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

-

Author Response

The reviewer did not provide any comments

Reviewer 2 Report

Comments and Suggestions for Authors

Minor issues:

Line 144: Correct misspelling: “worst-case”

Line 175: Check/Remove “[1][1]” before heading

Lines 193-200: Check formatting

Table 1: Check comment

Author Response

Minor issues:

Line 144: Correct misspelling: “worst-case”

Done

Line 175: Check/Remove “[1][1]” before heading

Done

Lines 193-200: Check formatting

Done

Table 1: Check comment

Done