Influence of the 2020 Seismic Hazard Update on Residential Losses in Greater Montreal, Canada

Round 1

Reviewer 1 Report

The manuscript "Influence of Seismic Hazard Update on Residential Losses in Greater Montreal, Canada" provides a detailed account of the difference that the newer seismic hazard model induces when estimating losses, as compared to the previous versions. It is and interesting and useful read. The manuscript is well organized and the results are of great importance to administrators, scientists and the public even though no new scientific advancement is inherent to the study. I consider the manuscript viable for publication and just offer some suggestions which might improve the clarity in presenting the results.

Comments for author File: Comments.pdf

Author Response

Thank you very much for your helpful comments. They help us to improve our manuscript.

Line 28. The reference [5] was inverted with another one in the list of references. Now we use: Adams J, Allen T, Halchuk S and Kolaj M. Canada’s 6th generation seismic hazard model, as prepared for the 2020 National Building Code of Canada. Proceeding of the 12th Canadian Conference on Earthquake Engineering, 2019. https://www.caee.ca/12CCEEpdf/192-Mkvp-139.pdf. The references are corrected in the text

Line 128. The reference [33] not available at the time of the submission is added Long, X. Estimation of the Annualized Earthquake Loss (AEL) for Residential Buildings in the Greater Montreal area using HAZUS and OpenQuake. Master of Engineering thesis, McGill University, 2023. https://escholarship.mcgill.ca/downloads/z029pb041?locale=en (last accessed 10 October 2023).

Line 139. A new figure (Fig. 13) with two maps showing the influence of the updated seismic hazard model on PGA and Loss is added in the discussion-conclusion part and the text is modified accordingly.

Line 221. A s is added to height

Reviewer 2 Report

The paper presents a study on the influence of seismic action update to the losses for residential buildings. The paper is interesting and I recommend acceptance. Few comments are reported below:

- The paper should present a framework, as applied in the case study. Hence, a flowchart about the steps performed by authors should be added

- How did authors retrieve vs30 information? Major details should be added

- What is the taxonomy used for buildings? Some references could help to justify the choice 

- The obtained results should be better justified. In general the higher cost in the risk models is provided by nonstructural elements as you present and I expect that also the increment of cost should be higher for these latter. Hence, in addition to the percentage, I would like to see the difference in absolute terms. 

- In the end, how did you consider buildings for the analysis? Fragility analysis seems to be very simplified 

Author Response

Thank you very much for your helpful comments. They help us to improve our manuscript. Our answers are in italic.

- The paper should present a framework, as applied in the case study. Hence, a flowchart about the steps performed by authors should be added

A flow chart is added as Figure 3 and a text explains it in the introduction.

- How did authors retrieve vs30 information? Major details should be added

Since the submission of the paper, a companion paper has been published in Geosciences (MDPI), which details the collected data, and the approach used to interpolate them. The paragraph is modified to reflect these changes and the reference added.

- What is the taxonomy used for buildings? Some references could help to justify the choice 

A paragraph is added in the section 2.3 (exposure model) to describe the taxonomy and a reference is added where the details are given.

- The obtained results should be better justified. In general the higher cost in the risk models is provided by nonstructural elements as you present and I expect that also the increment of cost should be higher for these latter. Hence, in addition to the percentage, I would like to see the difference in absolute terms. 

Table 3 details the results in absolute values for structural, non-structural and content values.

- In the end, how did you consider buildings for the analysis? Fragility analysis seems to be very simplified 

We don’t discuss the fragility curves issues since we use the one provided in Hazus. A paragraph in the conclusion mentioning that we will work on developing our own capacity curves and related fragility model in an ongoing project is modified.

Reviewer 3 Report

 

Dear Authors, Dear Editor,

I have completed my review of the manuscript “Influence of Seismic Hazard Update on Residential Losses in Greater Montreal, Canada” by Philippe Rosset, Janet Xuejiao and Luc Chouinard.

The methods employed are applicable, appropriately applied, and adequately described. The manuscript is well-written and supplemented with informative figures. It is in an advanced stage and does not requires, in my opinion, any revision prior to publication. I would only recommend: (i) to check eq. 1 and line 243 where CSds,i is cited (in eq. 1 is CSi); (ii) there are two typos at line 247 “..” instead of “).”; and “h” instead of “equations”, I suppose.

According to journal’ review guidelines, here are my additional comments.

1.What is the main question addressed by the research?

The manuscript primarily focuses on assessing the impact of changes in seismic hazard models (SHM5 and SHM6) on the estimation of damage and economic losses to residential buildings in the Montreal region, Canada.

Key points:

(i)             The manuscript provides the context regarding the seismic risk in the Montreal region (region's population density, seismic activity and the historical evolution of seismic hazard models).

(ii)            The Authors introduce the seismic hazard models, SHM5 and SHM6, and explains how these models have evolved over time, also highlighting the key improvements and changes made in each generation of the model.

(iii)          The Authors use “Hazus”, developed by FEMA and the National Institute of Building Sciences, to calculate damage and losses due to earthquakes. This tool has been widely used in North America and abroad for assessing the human and economic consequences of earthquakes.

(iv)          Special attention is given to the site condition model, which is essential for understanding how ground motion varies across different locations.

(v)            The main topic is the exploration of how changes in seismic hazard models have influenced the estimation of seismic risk, in particular on the consequences of the updated hazard models on building damage and economic losses. The Authors adequately discuss changes in the distribution of damage levels, the types of buildings most affected, and the financial implications of these changes.

(vi)          Finally, they discuss on the importance of quantifying and communicating uncertainties in seismic loss estimates and the need to consider these uncertainties when making decisions related to risk management and mitigation strategies,

 

2.Do you consider the topic original or relevant in the field? Does it address a specific gap in the field?

 

This study addresses the important topic of exploring the impact of national PSHA in seismic risk, an argument of wide interest.

 

3. What does it add to the subject area compared with other published material?

The present study adds several contributions to the subject area compared to other published material. I think that some key points are:

The manuscript primary contribution lies in its detailed comparison of two generations of seismic hazard models, SHM5 and SHM6. This comparative analysis allows for a direct assessment of how changes in hazard models can affect damage and economic loss estimates. Such a comparison is valuable for regions where seismic hazard modeling is evolving.

The manuscript emphasizes the importance of site conditions and how they affect ground motion. It discusses the influence of site-specific factors on seismic hazards, demonstrating a more comprehensive approach to risk assessment. This inclusion of localized geological and geotechnical data enhances the accuracy of the analysis.

The manuscript not only discusses the overall economic losses but also breaks down the impact on different building types. This level of granularity is essential for urban planners, engineers, and policymakers, as it helps prioritize risk mitigation strategies and building code revisions tailored to specific building categories.

In summary, the manuscript adds to the subject area of seismic risk assessment by providing a detailed analysis of Greater Montreal, offering a detailed comparison of seismic hazard models, considering site-specific conditions, utilizing a widely recognized tool, discussing uncertainty, focusing on different building types, and calling for continued research. These contributions enhance our understanding of seismic risk assessment in these regions and provide valuable insights for similar areas in other countries.

4. What specific improvements should the authors consider regarding the methodology? What further controls should be considered?

 I have no suggestions.

5. Are the conclusions consistent with the evidence and arguments presented and do they address the main question posed?

 Yes, they are consistent.

6. Are the references appropriate?

Yes

7. Please include any additional comments on the tables and figures.

Figure 11 is not so easy to read. Do you think it could be possible to map also a ratio of, for example, change of monetary loss in the dissemination areas?

Best Regards.

 

Author Response

Thank you very much for your helpful comments. They help us to improve our manuscript. Our answers are in italic

The methods employed are applicable, appropriately applied, and adequately described. The manuscript is well-written and supplemented with informative figures. It is in an advanced stage and does not requires, in my opinion, any revision prior to publication. I would only recommend: (i) to check eq. 1 and line 243 where CSds,i is cited (in eq. 1 is CSi); (ii) there are two typos at line 247 “..” instead of “).”; and “h” instead of “equations”, I suppose.

The paragraph related to equation 1 is modified for clarity and reference [8] of the most recent Hazus technical manual is provided.

Figure 11 is not so easy to read. Do you think it could be possible to map also a ratio of, for example, change of monetary loss in the dissemination areas?

A new figure (Fig. 13) with two maps showing the influence of the updated seismic hazard model on PGA and Loss is added in the discussion-conclusion part and the text modified accordingly.

Reviewer 4 Report

 

This is a well-written research paper with clear and understandable language, clear figures and tables which represent accurately the results The study design is appropriate for answering the research questions, a minor editing should be considered though.

Both abstract and Discussion are clearly written, giving an accurate summary of the research and results, without spin for the reviewer and the reader as long as it gets published and gets accessed to a broader audience.

As I mentioned above, the authors should consider some minor modifications in their research manuscript such as:

- Addition of a brief methodology section to move text from the introduction and add some elements on the Hazus software and restrict to some seismotectonic/historical earthquakes in the first paragraph.

- Map of figure 1 needs an inset general map of the region to point out where is the study area.

- You may also see to reformat the format of thousand e.g. 10,000 or 10000 instead of 10 000 due to possible confusion of the reader in some cases (Table 2, first line of data for instance).

- pg.1 line 28 use superscript to put 2 after km à km² 

- Finally, the research team should consider to either add a brief “conclusions” paragraph or transform “Discussion” section into “Discussion-Conclusions”. 

Overall, the soundness of the methodology and the conclusions can be supported by the results, with asignificant impact on the hazard assessement of the study area. Therefore, I recommend the research paper to be published after some minor changes (pointed out through this review) would be carried out.

Kind regards

 

 

 

 

 

 

Author Response

Thank you very much for your helpful comments. They help us to improve our manuscript. Our answers are in italic.

- Addition of a brief methodology section to move text from the introduction and add some elements on the Hazus software and restrict to some seismotectonic/historical earthquakes in the first paragraph.

A flow chart explaining the procedure to calculate damage and loss is added as Figure 3 and a text explains it in the introduction.

- Map of figure 1 needs an inset general map of the region to point out where is the study area.

The map is modified and an inset is added to locate the investigated region. The legend is changed accordingly.

- You may also see to reformat the format of thousand e.g. 10,000 or 10000 instead of 10 000 due to possible confusion of the reader in some cases (Table 2, first line of data for instance).

Space is replaced by “,” for numbers higher than 1,000.

- pg.1 line 28 use superscript to put 2 after km à km² 

Typos corrected

- Finally, the research team should consider to either add a brief “conclusions” paragraph or transform “Discussion” section into “Discussion-Conclusions”. 

We follow your advice and replace the title accordingly. This section is also improved by adding a new figure with two maps showing the influence of the updated seismic hazard model on PGA and Loss. and by improving part of the text.