English: Source: "Structural Measures Against Tsunamis", in: Federica Ranghieri, Mikio Ishiwatari (editors): Learning from Megadisasters - Lessons from the Great East Japan Earthquake, World Bank Publications, Washington, DC, 2014, ISBN (paper): 978-1-4648-0153-2, ISBN (electronic): 978-1-4648-0154-9, DOI: 10.1596/978-1-4648-0153-2, Chapter 1, pp. 25-32, here: p. 29, "Figure 1.4 Countermeasures against level 1 and level 2 tsunamis" (Source: Ministry of Land, Infrastructure, Transport and Tourism = MLIT). License: Creative Commons Attribution CC BY 3.0 IGO. Description from the mentioned source: "Since the GEJE, the Japanese government has taken a two-level approach. Level 1 includes tsunamis that occur as frequently as every 100 years and that cause significant damage, whereas level 2 covers the largest possible tsunami, which has an extremely low probability of occurrence (once every 1,000 years) but has the power to cause devastating destruction (figure 1.4)."