“Understanding disaster risk” is the first priority action of the Sendai Framework for Disaster Risk Reduction 2015–2030. During the Global Forum on Science and Technology for Disaster Resilience, held in Tokyo in November 2017, one of the working groups focused on this priority action and discussed the key aspects associated with understanding disaster risk. These included root causes and disaster risk drivers, disaster risk data, disaster risk assessment, disaster risk mapping, and collaboration among stakeholders. This paper reviews and illustrates the above topics by using three examples of the most devastating disasters of recent times: the 2004 Indian Ocean earthquake and tsunami, the 2010 Haiti earthquake, and the 2011 Great East Japan (Tohoku) Earthquake and Tsunami Disaster. The Indian Ocean tsunami, generated by the gigantic Sumatra-Andaman earthquake (magnitude M 9.1), caused 228,000 casualties from 14 countries because of its unexpected magnitude, the lack of knowledge on tsunamis and absence of an early warning system, and high levels of vulnerable populations, particularly elderly people, children, women, and foreign tourists. The 2010 Haiti earthquake, despite its smaller magnitude of M 7.0, also caused a similar number of casualties because of very high levels of vulnerability and exposure. Particularly relevant was the non-existence of building codes, political instability, extreme poverty, and poor health conditions. The 2011 Great East Japan Earthquake and Tsunami Disaster, caused by the gigantic Tohoku earthquake (M 9.0), produced approximately 22,000 casualties with a large proportion of elderly people, mostly because of wide spread, huge tsunamis. It also triggered the accident at the Fukushima Dai-ichi Nuclear Power Station, which is an example of a natural hazard triggering technological disaster. By examining these cases and based on the discussions carried out during the Forum, the working group adopted five recommendations.

1. [1] UNISDR (United Nations Office for Disaster Risk Reduction), “Sendai Framework for Disaster Risk Reduction 2015-2030,” United Nations, 36 pp., 2015. https://www.unisdr.org/files/43291_sendaiframeworkfordrren.pdf [accessed September 17, 2018]
2. [2] A. Oliver-Smith, “Haiti and the historical construction of disasters,” NACLA Report on the Americas, Vol.43, Issue 5, pp. 32-36, 2010.
3. [3] A. Oliver-Smith, I. Alcántara-Ayala, I. Burton, and A. Lavell, “Forensic Investigations of Disasters (FORIN): a conceptual framework and guide to research (IRDR FORIN Publication No.2),” Beijing: Integrated Research on Disaster Risk, ICSU, 56 pp., 2016. http://www.irdrinternational.org/wp-content/uploads/2016/01/FORIN-21.pdf [accessed September 17, 2018]
4. [4] A. Oliver-Smith, I. Alcántara-Ayala, I. Burton, and A. Lavell, “The social construction of disaster risk: seeking root causes,” Int. J. of Disaster Risk Reduction, Vol.22, pp. 469-474, 2017.
5. [5] A. Lavell, “Degradación ambiental, riesgo y desastre urbano: problemas y conceptos; hacia la definición de una agenda de investigación (Environmental degradation, risk and urban disaster: problems and concepts; towards the definition of a research agenda),” M. A. Fernández (ed.), Ciudades en riesgo: degradación ambiental, riesgos urbanos y desastres (Cities at risk: environmental degradation, urban risks and disasters), pp. 2-30, Lima: La Red., 1996 (in Spanish).
6. [6] P. Blaikie, T. Cannon, I. Davis,and B. Wisner, “At Risk: Natural Hazards, People’s Vulnerability and Disasters,” New York: Routledge, 1994.
7. [7] T. Cannon, “Vulnerability analysis and the explanation of ‘natural’ disasters,” A. Varley (ed.), Disasters, development and the environment, Chichester: John Wiley, 1994.
8. [8] E. Krausmann and D. Baranzini, “Natech risk reduction in the European Union,” J. Risk Research, Vol.15, Issue 8, pp. 1027-1047, 2012.
9. [9] K. Satake, “Advances in earthquake and tsunami sciences and disaster risk reduction since the 2004 Indian ocean tsunami,” Geoscience Letters, Vol.1, Article No.15, DOI: 10.1186/s40562-014-0015-7, 2014.
10. [10] J. Cosgrave, “Synthesis Report: Expanded Summary. Joint evaluation of the international response to the Indian Ocean tsunami,” Tsunami Evaluation Coalition, London, 50 pp., 2007. https://www.alnap.org/system/files/content/resource/files/main/Syn_Report_Sum.pdf [accessed September 17, 2018]
11. [11] P. Le Billon and A. Waizenegger “Peace in the wake of disaster? Secessionist conflicts and the 2004 Indian Ocean tsunami,” Trans. of the Institute of British Geographers, Vol.32, pp. 411-427, DOI: 10.1111/j.1475-5661.2007.00257.x, 2007.
12. [12] A. Oliver-Smith, “Haiti’s 500-year earthquake,” M. Schuller and P. Morales (eds.), Tectonic Shifts- Haiti since the earthquake, pp. 18-23, Kumarian Press, 2012.
13. [13] A. R. Kolbe, R. A. Hutson, H. Shannon, E. Trzcinski, B. Miles, N. Levitz, M. Puccio, L. James, J. R. Noel, and R. Muggah, “Mortality, crime and access to basic needs before and after the Haiti earthquake: a random survey of Port-au-Prince households,” Medicine, Conflict and Survival, Vol.26, Issue 4, pp. 281-297, DOI: 10.1080/13623699.2010.535279, 2010.
14. [14] Cabinet Office, “White Paper on Disaster Management 2011,” Executive Summary, http://www.bousai.go.jp/kaigirep/hakusho/pdf/WPDM2011_Summary.pdf [accessed September 17, 2018]
15. [15] K. Satake, “The 2011 Tohoku, Japan earthquake and tsunami,” A. Ismail-Zadeh, J. U. Fucugauchi, A. Kijko, Ku. Takeuchi, and I. Zaliapin (eds.), Extreme Natural Hazards, Disaster risks and Societal Implications, Cambridge University Press, pp. 310-321, 2014.
16. [16] International Atomic Energy Agency, “The Fukushima Daiichi Accident,” Vienna: International Atomic Energy Agency, 1254 pp., 2015.
17. [17] A. Lavell, “La gestión local del riesgo, nociones y precisiones en torno al concepto y la práctica (Local risk management, notions and precisions about the concept and practice),” CEPREDENAC–PNUD, 2013 (in Spanish).
18. [18] P. Dunbar, H. McCullough, G. Mungov, J. Varner, and K. Stroker, “2011 Tohoku earthquake and tsunami data available from the National Oceanic and Atmospheric Administration/National Geophysical Data Center,” Geomatics, Natural Hazards and Risk, Vol.2, Issue 4, pp. 305-323, DOI: 10.1080/2475705.2011.632443, 2011.
19. [19] S. Nishikawa, “Global Unique Disaster IDEntifier Number (GLIDE): For effective disaster information sharing and management,” Int. Conf. on Total Disaster Risk Management, pp. 89-92, 2003.
20. [20] B. D. M. Peary, R. Shaw, and Y. Takeuchi, “Utilization of social media in the east Japan earthquake and tsunami and its effectiveness,” J. Natural Disaster Sci., Vol.34, pp. 3-18, 2012.
21. [21] K. Murakami, “How to utilize ‘disaster big data’: Prospects on the use of disaster information in the future,” NHK Monthly Report on Broadcast Research, Vol.63, No.1, pp. 2-25, 2013 (in Japanese).
22. [22] Cabinet Office, “Summary of damage estimate and countermeasures for the earthquake beneath metropolitan Tokyo,” Tokyo: Government of Japan, 2005 (in Japanese). http://www.bousai.go.jp/jishin/syuto/past2/pdf/gaiyou.pdf [accessed September 17, 2018]
23. [23] Cabinet Office, “Summary of damage estimate and countermeasures for the earthquake beneath metropolitan Tokyo,” Tokyo: Government of Japan, 2013 (in Japanese). http://www.bousai.go.jp/jishin/syuto/taisaku_wg/pdf/syuto_wg_gaiyou.pdf [accessed September 17, 2018]
24. [24] S. L. Cutter, A. Ismail-Zadeh, I. Alcántara-Ayala, O. Altan, D. N. Baker, S. Briceño, H. Gupta, A. Holloway, D. Johnston, G. A. McBean, Y. Ogawa, D. Paton, E. Porio, R. K. Silbereisen, K. Takeuchi, G. B. Valsecchi, C. Vogel, and G. Wu, “Global risks: Pool knowledge to stem losses from disasters,” Nature, Vol.522, Issue 7556, pp. 277-279, 2015.
25. [25] E. Bernard (ed.), “Developing Tsunami-Resilient Communities; The National Tsunami Hazard Mitigation Program,” Springer, 184 pp., 2005 (reprinted from Natural Hazards, Vol.35, Issue 1).
26. [26] L. Tang, V. V. Titov, and C. D. Chamberlin, “Development, testing, and applications of site-specific tsunami inundation models for real-time forecasting,” J. Geophys. Res., Vol.114, C12025, DOI: 10.1029/2009JC005476, 2009.