Foreword of the publication Tsunami and Storm Surge Hazard Map Manual, by the Japanese Ministry of Land, Infrastructure and Transport.
Published in the International Centre for Water Hazard and Risk Management (ICHARM) under the asupices of UNESCO
Japan lies on the boundary of tectonic plates, and is prone to tsunamis during earthquakes that occur in submarine trenches. These have caused serious damage. Tsunamis are predicted to occur during earthquakes along the Japan Trench and Kuril Trench and during Tokai, Tonankai, and Nankai earthquakes. The country is also in the path of typhoons, and has frequently suffered storm surge damage. Rises in sea level due to climatic changes and increases in the scale of typhoons will probably increase storm surges. Thus, measures against tsunamis and storm surges must quickly be taken in Japan.
Advanced case studies have shown that hazard maps are an effective evacuation measure, and various attempts have been made to prepare hazard maps for tsunamis and storm surges. However, preparation of hazard maps that cover the entire country is at a standstill. This is probably because:
1) The staff of municipal governments in charge of disaster prevention and preparing hazard maps have no clear concept of tsunami and storm surge hazard maps,
2) The staff has no understanding of for whom tsunami and storm surge hazard maps are to be prepared, nor how to use such maps, and
3) Preparation of tsunami and storm surge hazard maps is technically difficult and expensive.
This manual aims to promote preparation of tsunami and storm surge hazard maps that cover the whole of Japan, and to assist the people in charge of preparation by providing information on 1) basic concepts of tsunami and storm surge hazard maps, such as the purposes of preparation, role allotment (support from national and prefectural governments), and utilization policies, and 2) standard methods for preparing tsunami and storm surge hazard maps, such as methods for identifying inundation risk areas, determining details to be stated on the maps, expressing those details, and utilizing the maps.
The manual assists in preparing and utilizing tsunami and storm surge hazard maps and shows essential points of technological systems and utilization methods. The methods described in this manual are merely a summary at today’s technical levels, and need to be revised along with technological development. New technologies, which are being constantly developed, should be actively incorporated according to the purposes of this manual.