Method to extract difficult-to-evacuate areas by using tsunami evacuation simulation and numerical analysis

Extracting the area where people have difficulty evacuating (hereafter difficult-to-evacuate areas, DEA) when tsunamis hit after an earthquake is important for effective disaster mitigation measures. The DEA was conven-tionally extracted by simply considering the walking speed, distance to the evacuation destination, and time needed for evacuation after considering the estimated tsunami inundation area. However, evaluating the DEA from such a simple scheme is insufficient because the behavior of residents and the road conditions to the evacuation destinations after an earthquake are not properly reflected in the scheme. In this study, agent-based tsunami evacuation simulations that can reflect the behavior of residents and real -time changes in the situation were conducted in Zihuatanejo, Guerrero, Mexico. It is a prime sightseeing destination under the high risk of megathrust events in the Guerrero Gap. First, by checking the simulation images at the tsunami arrival time, bottleneck locations were identified, and five additional models with different measures for the bottleneck locations were constructed and tested to find the best model with 195 casualties. Then, focusing on the best model, three indices for the casualties were proposed to extract the DEA effectively and quantitatively, and numerical analyses using the three indices was conducted. Finally, the subdistrict in the center of the target area (subdistrict 5) was quantitatively found to be the district that should be given the highest priority for measures. Moreover, an example model with a new measure in subdistrict 5 was validated to have 101 casualties. The key points for applying the proposed method for extraction of DEA in other areas are summarized

Evaluation of The Road Vulnerability Network During the Evacuation Process (A Case Study in A Coastal Area of Bengkulu City, Indonesia)

This study aims to determine the road network's performance for the Pantai Panjang and Bencoolen Mall areas in Bengkulu City, Indonesia, if a tsunami disaster occurs. The traffic on roads and questionnaire survey on respondents who occasionally come to the study areas is performed. The numerical analysis is conducted using four-step modelling based on various road condition scenarios to evaluate the road network performance. Scenario 1 considers existing conditions during tsunami evacuation; Scenario 2 considers increasing road capacity and adding two new road sections using traffic flow simulation during tsunami evacuation; Scenario 3 considers the addition of one new road section using traffic flow simulation during tsunami evacuation. For Scenarios 4, 5 and 6, the previous scenarios are evaluated by considering the increase in vehicle numbers in the next five years. Scenarios 1 and 4 show that there is an increase in the degree of saturation up to 0.68. It shows that the level of road service decreases. The road modification scenarios (Scenarios 2 and 3) show improved service levels. The modelling results with scenarios using traffic flow data under the improvement of road service for the next five years (Scenarios 5 and 6) show that the level of road service is better than the existing model. The road modifications scenario also effectively reduces the vulnerability index. The local government could also consider the results to improve the tsunami disaster mitigation in the study area

An operational research-based integrated approach for mass evacuation planning of a city

Large-scale disasters are constantly occurring around the world, and in many cases evacuation of regions of city is needed. ‘Operational Research/Management Science’ (OR/MS) has been widely used in emergency planning for over five decades. Warning dissemination, evacuee transportation and shelter management are three ‘Evacuation Support Functions’ (ESF) generic to many hazards. This thesis has adopted a case study approach to illustrate the importance of integrated approach of evacuation planning and particularly the role of OR/MS models. In the warning dissemination phase, uncertainty in the household’s behaviour as ‘warning informants’ has been investigated along with uncertainties in the warning system. An agentbased model (ABM) was developed for ESF-1 with households as agents and ‘warning informants’ behaviour as the agent behaviour. The model was used to study warning dissemination effectiveness under various conditions of the official channel. In the transportation phase, uncertainties in the household’s behaviour such as departure time (a function of ESF-1), means of transport and destination have been. Households could evacuate as pedestrians, using car or evacuation buses. An ABM was developed to study the evacuation performance (measured in evacuation travel time). In this thesis, a holistic approach for planning the public evacuation shelters called ‘Shelter Information Management System’ (SIMS) has been developed. A generic allocation framework of was developed to available shelter capacity to the shelter demand by considering the evacuation travel time. This was formulated using integer programming. In the sheltering phase, the uncertainty in household shelter choices (either nearest/allocated/convenient) has been studied for its impact on allocation policies using sensitivity analyses. Using analyses from the models and detailed examination of household states from ‘warning to safety’, it was found that the three ESFs though sequential in time, however have lot of interdependencies from the perspective of evacuation planning. This thesis has illustrated an OR/MS based integrated approach including and beyond single ESF preparedness. The developed approach will help in understanding the inter-linkages of the three evacuation phases and preparing a multi-agency-based evacuation planning evacuatio

Handbook of Tsunami Evacuation Planning - SCHEMA (Scenarios for Hazard-induced Emergencies Management), Project n° 030963, Specific Targeted Research Project, Space Priority

This handbook is dedicated to provide thorough and hands-on information in order to produce fully-comprehensive methodology of tsunami evacuation plan generation. Hence community-employed decision makers or similar stakeholders are supplied with a detailed guideline to implement a fully-fledged evacuation plan within three stages : set-up of valid first instance of evacuation plan, mid-term revision, and long-term revision and integration. Local tsunami risk assessment and all subsequent implications on evacuation planning are based on (1) knowing the to-be-expected tsunami wave height, and (2) the to-be-expected arrival time of the first devastating tsunami wave. The first parameter helps to calculate the area at risk ; the second parameter gives an indication of how fast the evacuation has to take place. Consequently, the evacuation plan instance must guarantee that a certain number of affected persons has to be brought onto safe areas within a given time limit. Safe areas (shelters) are higher located places, either on natural ground, or on artificially built-up constructions including building higher than three stores. Evacuation has to take place on a given network of suitable roads or paths. In this context, if necessary, the methodology foresees also the inclusion of additionally to be built escape routes and/or safe places in order to produce a fully working evacuation plan that fulfills the basic requirements. The methodology also explains how to implement a valid instance of evacuation plan by marking the identified escape routes and shelters in reality, and how to disseminate all information to the affected population. Within a mid-term review the evacuation plan has to be maintained constantly and appropriate authority-own measures have to be guaranteed. The long-term review, finally, keeps track of all other information needed to run the evacuation plan properly : integration with early-warning systems, integration with other emergency plans, checking of legal obligations. In addition, the whole evacuation plan must be reviewed together with the affected population and a maximum of acceptance be obtained. In this contaxt, and if necessary, adaptations should be made in order to guarantee the well-functioning of the whole plan within its best performance.JRC.DG.G.7-Traceability and vulnerability assessmen

Tsunami risk communication and management: Contemporary gaps and challenges

Very large tsunamis are associated with low probabilities of occurrence. In many parts of the world, these events have usually occurred in a distant time in the past. As a result, there is low risk perception and a lack of collective memories, making tsunami risk communication both challenging and complex. Furthermore, immense challenges lie ahead as population and risk exposure continue to increase in coastal areas. Through the last decades, tsunamis have caught coastal populations off-guard, providing evidence of lack of preparedness. Recent tsunamis, such as the Indian Ocean Tsunami in 2004, 2011 Tohoku and 2018 Palu, have shaped the way tsunami risk is perceived and acted upon. Based on lessons learned from a selection of past tsunami events, this paper aims to review the existing body of knowledge and the current challenges in tsunami risk communication, and to identify the gaps in the tsunami risk management methodologies. The important lessons provided by the past events call for strengthening community resilience and improvement in risk-informed actions and policy measures. This paper shows that research efforts related to tsunami risk communication remain fragmented. The analysis of tsunami risk together with a thorough understanding of risk communication gaps and challenges is indispensable towards developing and deploying comprehensive disaster risk reduction measures. Moving from a broad and interdisciplinary perspective, the paper suggests that probabilistic hazard and risk assessments could potentially contribute towards better science communication and improved planning and implementation of risk mitigation measures

Tsunami risk communication and management: Contemporary gaps and challenges

Very large tsunamis are associated with low probabilities of occurrence. In many parts of the world, these events have usually occurred in a distant time in the past. As a result, there is low risk perception and a lack of collective memories, making tsunami risk communication both challenging and complex. Furthermore, immense challenges lie ahead as population and risk exposure continue to increase in coastal areas. Through the last decades, tsunamis have caught coastal populations off-guard, providing evidence of lack of preparedness. Recent tsunamis, such as the Indian Ocean Tsunami in 2004, 2011 Tohoku and 2018 Palu, have shaped the way tsunami risk is perceived and acted upon. Based on lessons learned from a selection of past tsunami events, this paper aims to review the existing body of knowledge and the current challenges in tsunami risk communication, and to identify the gaps in the tsunami risk management methodologies. The important lessons provided by the past events call for strengthening community resilience and improvement in risk-informed actions and policy measures. This paper shows that research efforts related to tsunami risk communication remain fragmented. The analysis of tsunami risk together with a thorough understanding of risk communication gaps and challenges is indispensable towards developing and deploying comprehensive disaster risk reduction measures. Moving from a broad and interdisciplinary perspective, the paper suggests that probabilistic hazard and risk assessments could potentially contribute towards better science communication and improved planning and implementation of risk mitigation measures

Tsunami evacuation model for Sumner, Christchurch, New Zealand

Sumner, a coastal suburb located to the south-east of Christchurch, New Zealand, is highly exposed to a number of tsunami hazards. In tsunami mitigation plans, evacuation plays a crucial role in saving human lives, especially for communities located in low-lying coastal areas. The aim of this thesis is to enhance the methodological basis for development of tsunami evacuation plans in Sumner. To achieve this, a numerical simulation output of far-field tsunami impacts in Sumner was used to establish the maximum likely inundation extent and flow depth. This, together with population census data and daily activity patterns specified for the study area, established the spatio-temporal basis for characterising population exposure to the tsunamic hazard. A geospatial evacuation analysis method (Least Cost Path Distance), augmented with variable population exposure and distributed travel speeds, was used to characterise spatial variation in evacuation times and the corresponding numbers of evacuees and vehicles. Three ‘extreme’ end-member scenarios were utilised to address possible evacuation methods; all pedestrians evacuated to 20 metres elevation, all pedestrians to bus stops for evacuation using public transport, and all people evacuated using private vehicles. This thesis has made a methodological contribution to tsunami evacuation simulation by characterising variable spatio-temporal population exposure, and incorporating terrain properties into population and vehicle movements. The methods are equally applicable to other locations, to other hazards, and for both pre- and post-disaster evacuation analyses

Tsunami evacuation times and routes to safe zones: a GIS-based approach to tsunami evacuation planning on the island of Stromboli, Italy

Funder: IDEX-ISITE initiative16-IDEX-0001 (CAP 20-25)AbstractWhile a landslide at the volcanic island of Stromboli (Aeolian Islands, Italy) in December 2002 created a tsunami with a run-up of 10.9 m, two paroxysmal eruptions in the summer of 2019 caused a tsunami with an amplitude of 40 to 20 cm. All three events required rapid, spontaneous emergency evacuations of the beach zone as the time between tsunami generation and impact is around 4 min. These conditions thus require a special consideration of the issue of evacuation capabilities on the island in the event of a volcanogenic tsunami. The purpose of this paper is thus to (i) determine pedestrian evacuation times from high-risk coastal areas to safe zones, (ii) to assess building evacuation ease, and (iii) determine emergency evacuation plans (for buildings and coastal zones). For this purpose, we created a GIS-based risk analysis/mapping tool that also allowed macroscopic evacuation modelling. In our case, the high-risk zone to be evacuated involves an area extending to 10 m a.s.l. and involving 123 individual buildings over an area of 0.18 km2. The results show that 33% of the buildings can be evacuated in 4 min, and that a 10-min warning time is required for a complete and well-distributed evacuation whereby the population is evenly distributed between all evacuation exits to avoid the potential for congestion. Initial interviews of residents in the at-risk zone reveal a high level of awareness and a desire for personalized evacuation scenarios.</jats:p

Modelling mass evacuations to improve the emergency planning for floods in the UK, the Netherlands and North America

Whether to implement a mass evacuation of people from an area at risk of flooding can be a major issue for emergency managers. The modelling of the evacuation process generated by a forecast flood is important for those responsible for the efficient and safe movement of people during evacuations. Evacuation modelling can predict “bottlenecks” in the system before they are experienced, it can also be used to determine the impact of road closures due to flooding and the impact of phased evacuation on traffic loading. Being able to model alternative evacuation scenarios can lead to the establishment of appropriate evacuation policies and shelter strategies. With the increasing use of two dimensional hydraulic models that can provide accurate estimates of floodwater velocity and depth, and with the increased availability and accessibility of spatially-referenced population data and transport links, the modelling of mass evacuations for floods has increased. The model results can be used to assess the best locations of shelters and options for traffic management. This paper provides details of models and case studies carried out in the UK, North America and the Netherlands to estimate the evacuation times of tens of thousands of people that reside in flood risk areas. The models discussed in this paper range from “micro-models” to “macro-models”. Micro-models simulate each individual person at risk, and give a detailed representation of the evacuation routes. Coarser macro-models estimate evacuation times based on key parameters such as “lumped” population groups, the distance to the nearest shelter or higher ground, the evacuation route, and the average evacuation speed. The paper provides conclusions on the suitability of different evacuation models, as well as on the scale at which these models can be applied; their suitability for evacuation planning; and the “usefulness” of the results to various actors involved in the emergency planning process