Post-Disaster Impact Assessment: A Toolbox for Saving Lives in a Changing World

Natural disasters such as earthquakes, tsunamis, hurricanes and floods affect millions of people every year. Climate change will likely add to the natural disasters which already occur around the world. The global climate is warming, causing increases in tropical storms; desert areas are becoming drier, contributing to increases in droughts and food shortages; and land-glaciers are melting, leading to an increase in avalanches and landslides [1][4]. In addition to these climate-driven disasters, the Earth is continuously undergoing geologic changes which result in volcanic eruptions, landslides and earthquakes. With growing populations near hazard-prone areas, post-disaster impact assessment is going to be an important toolbox for rebuilding in safer areas and saving lives. 

Original Data from the EM-DAT International Disaster Database, Center for Research on the Epidemiology of Disasters, University of Louvain (

Figure 1: A steady increase in climate-related natural disasters is apparent from the blue bar plot in this graph (Source [3])

 On March 11, 2011, Eastern Japan was hit by a magnitude-9.0 earthquake and subsequent 40.5 meter-high tsunami which killed over 19,000 people and destroyed 835 000 homes [5][6]. Japan is a developed county known for having countermeasures and evacuation plans for tsunami disasters [5]. They utilize both hard (i.e. breakwaters and sea walls) and soft (i.e. awareness and education) mitigation measures to ensure the minimize loss of life [5].


Figure 2: Shows Japan and many other countries’ vulnerability due to the “Ring of Fire”, an extremely active zone of crustal plate boundaries (Source:

Impact assessment for damages was used to determine the performance of buildings materials and to record which locations were most vulnerable to flooding and sea level rise. Post-disaster on-the-ground fieldwork can be coupled with GIS tools to assess damages and to plan for the future. GIS technologies were used after the 2011 tsunami to show how well the hard mitigation measures performed. Types of GIS data that can be used are: elevation maps to map vulnerable areas and to locate shelters away from flood-prone land, land use to map vulnerability of structures and towns, and road networks to map access routes to affected areas [2]. For example, vulnerability assessment was done by mapping housing damage in vulnerable inundation areas and assessing “fragility curves” for different types of construction materials [5]. Disaster Science and Engineering experts Suppasri et al. (2013) were able to visually inform Japanese authorities of the best construction materials to be used in future development projects.

Examples of different damage levels for the same tsunami inundation depth. Figure from [4], page 1005

Figure 3: Examples of different damage levels for the same tsunami inundation depth (Source [5], p.1005)

Mapping disaster damage coupled with on-the-ground studies such as photographs and written accounts are essential for informing policy for future improvements to counter-disaster management strategies.  As shown above, this can also be said for types of construction materials used for building homes to increase resilience against tsunamis. Furthermore, GIS applications could be used to map historical inundation areas to plan new prevention plans, choose evacuation areas, and to visually inform residents of their location’s vulnerability to natural disasters such as tsunamis [5]. Scenario analysis mapping is an essential tool to be used to inform policy in choosing relocation areas away from vulnerable coastlines, as well as away from other potential natural disaster areas (e.g. landslides and floods).

On a warming planet where natural hazards have the potential to augment, and where societies will continue to be subject to various geologic hazards, post-disaster impact assessors will be needed to contribute to reconstruction efforts and to inform future disaster-planning in vulnerable areas.

Works Cited

[1] Bury, J.T. et al. (2011). Glacier recession and human vulnerability in the Yanamarey watershed of the Cordillera Blanca, Peru. Climatic Change , 105, 179-206.

[2] Latif, S., Islam, R., Khan, M. I., & Ahmed, S. I. (2011). OpenStreetMap for the Disaster Management in Bangladesh. IEEE Conference on Open Systems, (pp. 429-433). Langkawi, Malaysia.

[3] Leaning, J., & Guha-Sapir, D. (2013). Natural Disasters, Armed Conflict, and Public Health. New England Journal of Medicine, 369(19), 1836-1842.

[4] Malone, E. L., & Engel, N. L. (2011). Evaluating regional vulnerability to climate change: purposes and methods. WIREs Climate Change , 2, 462-474.

[5] Suppasri, A., Shuto, N., Imamura, F., Koshimura, S., Mas, E., & Yalciner, A. C. (2013). Lessons Learned from the 2011 Great East Japan Tsunami: Performance of Tsunami Countermeasures, Coastal Buildings, and Tsunami Evacuation in Japan. Pure and Applied Geophysics , 170, 993-1018.

[6] Utani, A., Mizumoto, T., & Okumura, T. (2011). How geeks responded to a catastrophic disaster of a high-tech country: rapid development of counter-disaster systems for the great east Japan earthquake of March 2011. Proceedings of the Special Workshop on Internet and Disasters, (pp. 1-8). Tokyo, Japan.


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