the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 15 Aug 2023
Analysis of the effects of urban micro-scale vulnerabilities on tsunami evacuation using and Agent-Based model. Case study in the city of Iquique, Chile
Abstract. The occurrence of mega tsunamis over the last couple of decades has greatly increased the attention of the research community and practitioners to work hand in hand to reduce risks from these highly destructive threats. Protecting the population through evacuation is the best alternative for avoiding loss of life in the wake of the occurrence of a tsunamigenic earthquake. Therefore, guaranteeing the proper state of evacuation routes is very important to ensure appropriate movement to the safe zones. This study carries out a detailed analysis of possible evacuation scenarios, considering the actual state of the escape routes of Iquique, a Chilean city prone to tsunamis, with a substantial amount of urban micro-scale vulnerabilities, i.e., elements that obstruct or complicate pedestrian flow. The quantification of the delay in evacuation processes resulting from the presence of urban micro-vulnerabilities is carried out through micro-scale Agent-Based Modeling (ABM). In addition, these results are integrated with high-resolution tsunami inundation simulations, allowing for an estimation of the potential number of people that the tsunami may reach under different scenarios, by emulating the dynamics and behavior of the population and the decision making regarding the starting time of the evacuation.
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Status: closed
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RC1: 'Comment on nhess-2023-139', Anonymous Referee #1, 05 Sep 2023
Until recently tsunami numerical studies were primary concentrated on the hazard side less focusing on damage and loss assessment. Rapid development of computational facilities and corresponding numerical codes coupled to collection of high precision and high resolution topo-bathymetric and exposure data allow nowadays detailed and reliable simulations of tsunami inundation and impact scenarios. Tsunami modeling community is putting more and more efforts in exploring methodologies to assess potential tsunami damages and losses and, consequently, factors controlling them in order to propose effective counter-measures. In this respect, current manuscript is an important step forward. Authors present and evaluate quantitative coupled tsunami simulation / agend-based methodology to assess the effectiveness of evacuation in presence of artificial obstacles along evacuation routes. The Manuscript is concise, well structured and easy to read. I do not have any major objections and recommend publishing after minor revisions.
First of all I have two comments/suggestions regarding the methodology. They both concern daytime to nighttime variations.
(1) Authors analyze the effect of „micro-scale vulnerabilities“, i.e. obstacles along evacuation routes. These may include e.g. restaurant infrastructure – tables, chairs, – or shop‘s advertisement objects placed directly on street sidewalks. This obstacles are usually removed from the streets during the night time, means the distribution of obstacles may be also time-dependent.
(2) Also the average evacuation starting time should probably be different for day and night. Just because people at night, while being awakened by strong shaking or sirens, won‘t be so effective in starting their evacuation as it could be during the day.
I do not ask to implement these options in the present study but just to discuss their feasibility for future studies.
Other minor remarks.
- References to Satake 2014a and b are the same.
- L102: It is better to define „urban friction rate“ here, in a following sentence.
- L159: Maybe refer to Fig. 9 which illustrates distribution of MSV along the evacuation route.
- Sect.3.4: which tool was used for the agend-based modeling? Authors describe components of the ABM in the first paragraph of this section, but do not mention the modeling tool.
- Fig.6: This Figure could be much more informative. First of all, the current figure size does not allow to recognize enough details – I suggest to make both plots much larger: at least half page each. One should be able to see the details of the inundation patterns. For that please also „resolve“ the blue color: now it encompasses arrival times from 0 to 45 minutes – the most important time span unfortunately not resolved at all. High spatial and temporal resolution would also help to understand the abrupt arrival time gradient (from less than 15 to more than 90 minutes) observed at the left plot. Additionally, I think, it is necessary to show the distribution of the initial tsunami wave height offshore. That would help to interpret extreme short arrival times. This can be done using larger-scale inlets and/or integrated into the image. Currently the blue ocean is confusing: is it bathymetry? Or arrival times as well? In the latter case they seem to be inconsistent with dark-blue (=earlier) arrivals on land.
Fig.7: Empirical evacuation curves start from 10 or 17 minutes. Were there absolutely no people in the vicinity of the safe zones? With 76000 drill participants it may seem indeed strange. Just looking at this Figure, I would propose to critically re-assess the methodology of the average starting time to make it more compatible to observations.
Fig. 8 and L225: Looking at the Figure 8, I cannot agree that for the case of „8-min starting time“, time needed to get to the safe zone is 50 minutes. Actually comparing daytime dashed and solid lines, I would evaluate the time difference between them as „less than 10 minutes“. Thus, if at t=30 min solid lines reach the level of ca. 4400 evacuees, the same level will be reached by dashed lines at t~38 min. Therefore, time difference between „3 and 8-min“ scenarios seems to be much less than imposed 20 (50 vs 30) minutes.
Citation: https://doi.org/10.5194/nhess-2023-139-RC1 -
AC1: 'Reply on RC1', Rodrigo Cienfuegos, 08 Nov 2023
Dear Editors,
we acknolwedge the careful revisions we received from the two referees, which we believe have been important to improve our research manuscript. In the file attached to this communication, you will find the answers to each of the queries raised by referee 1.
Kind regards,
Rodrigo Cienfuegos
-
AC1: 'Reply on RC1', Rodrigo Cienfuegos, 08 Nov 2023
-
RC2: 'Comment on nhess-2023-139', Anonymous Referee #2, 11 Sep 2023
A review on the manuscript “Analysis of the effects of urban micro-scale vulnerabilities on tsunami evacuation using and Agent-Based model. Case study in the city of Iquique, Chile” written by Rodrigo Cienfuegos, Gonzalo Álvarez, Jorge León, Alejandro Urrutia, and Sebastián Castro
The manuscript presents an analysis of the challenges surrounding tsunami evacuations, with a focus on Iquique, Chile. Using an Agent-Based Modeling (ABM) and tsunami inundation simulations, the study quantifies the evacuation processes resulting from urban micro-vulnerabilities and other factors. This research has a significant contribution, emphasizing the necessity of addressing such vulnerabilities in disaster management. The manuscript can be accepted for publication after a minor revision.
Here are some of the suggestions for improvement. My main concern is on the introduction part.
- There is a typo in the title. “and”- >”an”
- The introduction lacks a clear and explicit statement of the article's main thesis or research question. It would greatly benefit from a more precise outline of the study's objectives, the specific questions it aims to address, and a clear description of how it contributes to existing research in comparison to previous studies.
- While historical context is important, the introduction dedicates a substantial portion of its content to discussing past tsunamis and their consequences. This historical background information could be streamlined to allow for a more focused and concise introduction that directly introduces the study's subject matter.
- In Section 4.2, titled "Validation of the Rayleigh evacuation curve," the term "validation" might not be entirely accurate. Rather, it appears to be a comparison to previous evacuation drills. The discrepancy in the average starting times between the ABM simulations and the actual drills (3 minutes vs. 10 to 17 minutes) raises questions about the model's validation. Additionally, the duration required to achieve close to 100% evacuation seems to be faster in the case of the drills, suggesting that the ABM model may not be accurately validated for this aspect. A more precise description of the model's performance and limitations in comparison to real-world data would be beneficial.
- In Section 5, L257 states “In Figure 10 we show the differences in the number of evacuees for the ABM simulations with and without urban micro-scale vulnerabilities.” However, Figure 10 does not show the results “with and without urban micro-scale vulnerabilities”.
L17 “Tsunami research has come a long way after this event” -> unclear what this implies
L54 “possible only” -> “only possible”
L71 “The largest reported earthquakes in recent centuries in the area” -> “The most notable seismic events recorded in the region in recent centuries include”
L236 “16 %” -> Is it 9.7 % ?
Figure 3&4 Recommend to plot the location of DARTs in Figure 3.
Figure 6. Change the color scheme. It is difficult to distinguish the arrival time between 15 min and 20 min.
Citation: https://doi.org/10.5194/nhess-2023-139-RC2 -
AC2: 'Reply on RC2', Rodrigo Cienfuegos, 08 Nov 2023
Dear Editors,
we acknolwedge the careful revisions we received from the two referees, which we believe have been important to improve our research manuscript. In the file attached to this communication, you will find the answers to each of the queries raised by referee 2.
Kind regards,
Rodrigo Cienfuegos
Status: closed
-
RC1: 'Comment on nhess-2023-139', Anonymous Referee #1, 05 Sep 2023
Until recently tsunami numerical studies were primary concentrated on the hazard side less focusing on damage and loss assessment. Rapid development of computational facilities and corresponding numerical codes coupled to collection of high precision and high resolution topo-bathymetric and exposure data allow nowadays detailed and reliable simulations of tsunami inundation and impact scenarios. Tsunami modeling community is putting more and more efforts in exploring methodologies to assess potential tsunami damages and losses and, consequently, factors controlling them in order to propose effective counter-measures. In this respect, current manuscript is an important step forward. Authors present and evaluate quantitative coupled tsunami simulation / agend-based methodology to assess the effectiveness of evacuation in presence of artificial obstacles along evacuation routes. The Manuscript is concise, well structured and easy to read. I do not have any major objections and recommend publishing after minor revisions.
First of all I have two comments/suggestions regarding the methodology. They both concern daytime to nighttime variations.
(1) Authors analyze the effect of „micro-scale vulnerabilities“, i.e. obstacles along evacuation routes. These may include e.g. restaurant infrastructure – tables, chairs, – or shop‘s advertisement objects placed directly on street sidewalks. This obstacles are usually removed from the streets during the night time, means the distribution of obstacles may be also time-dependent.
(2) Also the average evacuation starting time should probably be different for day and night. Just because people at night, while being awakened by strong shaking or sirens, won‘t be so effective in starting their evacuation as it could be during the day.
I do not ask to implement these options in the present study but just to discuss their feasibility for future studies.
Other minor remarks.
- References to Satake 2014a and b are the same.
- L102: It is better to define „urban friction rate“ here, in a following sentence.
- L159: Maybe refer to Fig. 9 which illustrates distribution of MSV along the evacuation route.
- Sect.3.4: which tool was used for the agend-based modeling? Authors describe components of the ABM in the first paragraph of this section, but do not mention the modeling tool.
- Fig.6: This Figure could be much more informative. First of all, the current figure size does not allow to recognize enough details – I suggest to make both plots much larger: at least half page each. One should be able to see the details of the inundation patterns. For that please also „resolve“ the blue color: now it encompasses arrival times from 0 to 45 minutes – the most important time span unfortunately not resolved at all. High spatial and temporal resolution would also help to understand the abrupt arrival time gradient (from less than 15 to more than 90 minutes) observed at the left plot. Additionally, I think, it is necessary to show the distribution of the initial tsunami wave height offshore. That would help to interpret extreme short arrival times. This can be done using larger-scale inlets and/or integrated into the image. Currently the blue ocean is confusing: is it bathymetry? Or arrival times as well? In the latter case they seem to be inconsistent with dark-blue (=earlier) arrivals on land.
Fig.7: Empirical evacuation curves start from 10 or 17 minutes. Were there absolutely no people in the vicinity of the safe zones? With 76000 drill participants it may seem indeed strange. Just looking at this Figure, I would propose to critically re-assess the methodology of the average starting time to make it more compatible to observations.
Fig. 8 and L225: Looking at the Figure 8, I cannot agree that for the case of „8-min starting time“, time needed to get to the safe zone is 50 minutes. Actually comparing daytime dashed and solid lines, I would evaluate the time difference between them as „less than 10 minutes“. Thus, if at t=30 min solid lines reach the level of ca. 4400 evacuees, the same level will be reached by dashed lines at t~38 min. Therefore, time difference between „3 and 8-min“ scenarios seems to be much less than imposed 20 (50 vs 30) minutes.
Citation: https://doi.org/10.5194/nhess-2023-139-RC1 -
AC1: 'Reply on RC1', Rodrigo Cienfuegos, 08 Nov 2023
Dear Editors,
we acknolwedge the careful revisions we received from the two referees, which we believe have been important to improve our research manuscript. In the file attached to this communication, you will find the answers to each of the queries raised by referee 1.
Kind regards,
Rodrigo Cienfuegos
-
AC1: 'Reply on RC1', Rodrigo Cienfuegos, 08 Nov 2023
-
RC2: 'Comment on nhess-2023-139', Anonymous Referee #2, 11 Sep 2023
A review on the manuscript “Analysis of the effects of urban micro-scale vulnerabilities on tsunami evacuation using and Agent-Based model. Case study in the city of Iquique, Chile” written by Rodrigo Cienfuegos, Gonzalo Álvarez, Jorge León, Alejandro Urrutia, and Sebastián Castro
The manuscript presents an analysis of the challenges surrounding tsunami evacuations, with a focus on Iquique, Chile. Using an Agent-Based Modeling (ABM) and tsunami inundation simulations, the study quantifies the evacuation processes resulting from urban micro-vulnerabilities and other factors. This research has a significant contribution, emphasizing the necessity of addressing such vulnerabilities in disaster management. The manuscript can be accepted for publication after a minor revision.
Here are some of the suggestions for improvement. My main concern is on the introduction part.
- There is a typo in the title. “and”- >”an”
- The introduction lacks a clear and explicit statement of the article's main thesis or research question. It would greatly benefit from a more precise outline of the study's objectives, the specific questions it aims to address, and a clear description of how it contributes to existing research in comparison to previous studies.
- While historical context is important, the introduction dedicates a substantial portion of its content to discussing past tsunamis and their consequences. This historical background information could be streamlined to allow for a more focused and concise introduction that directly introduces the study's subject matter.
- In Section 4.2, titled "Validation of the Rayleigh evacuation curve," the term "validation" might not be entirely accurate. Rather, it appears to be a comparison to previous evacuation drills. The discrepancy in the average starting times between the ABM simulations and the actual drills (3 minutes vs. 10 to 17 minutes) raises questions about the model's validation. Additionally, the duration required to achieve close to 100% evacuation seems to be faster in the case of the drills, suggesting that the ABM model may not be accurately validated for this aspect. A more precise description of the model's performance and limitations in comparison to real-world data would be beneficial.
- In Section 5, L257 states “In Figure 10 we show the differences in the number of evacuees for the ABM simulations with and without urban micro-scale vulnerabilities.” However, Figure 10 does not show the results “with and without urban micro-scale vulnerabilities”.
L17 “Tsunami research has come a long way after this event” -> unclear what this implies
L54 “possible only” -> “only possible”
L71 “The largest reported earthquakes in recent centuries in the area” -> “The most notable seismic events recorded in the region in recent centuries include”
L236 “16 %” -> Is it 9.7 % ?
Figure 3&4 Recommend to plot the location of DARTs in Figure 3.
Figure 6. Change the color scheme. It is difficult to distinguish the arrival time between 15 min and 20 min.
Citation: https://doi.org/10.5194/nhess-2023-139-RC2 -
AC2: 'Reply on RC2', Rodrigo Cienfuegos, 08 Nov 2023
Dear Editors,
we acknolwedge the careful revisions we received from the two referees, which we believe have been important to improve our research manuscript. In the file attached to this communication, you will find the answers to each of the queries raised by referee 2.
Kind regards,
Rodrigo Cienfuegos
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