**5. Conclusion**

This chapter introduced how remote sensing can be applied for tsunami research fields. In general, remote sensing is used for rapid and large-scale damage detection to understand the scale of a tsunami, especially when accessibility to disaster-affected areas is limited in the immediate aftermath. Some of the general applications shown in this chapter are related to the tsunami inundation limit, damaged buildings/debris and mangrove recovery monitoring. SAR images are used to determine tsunami-affected areas using the reflection property or backscattering coefficient as mentioned in the previous section. The next step focused on damage classification in a tsunami affected area, i.e., structural damage of housing or buildings. The benefit of high-resolution images from the sky helps tsunami researchers interpret the tsunami damage level based on roofs. A one-metre resolution, such as that of IKONOS, could help classify buildings as destroyed or not destroyed. In addition, a very high-resolution satellite image such as QuickBird (0.6 m resolution) was used to classify a number of levels, i.e., washed-away, collapsed, major damage or survived. Some recent research on tsunami events was introduced, namely, the 1993 Hokkaido Nansei-oki tsunami, the 2004 Indian Ocean tsunami, the 2007 Solomon tsunami, the 2009 Samoa tsunami, the 2010 Chile tsunami and the most recent 2011 Tohoku tsunami. However, information from the sky has some limitations because it is impossible to make a detailed damage inspection of a structural member, and it might have some errors compared with an actual field survey. Finally, classified structural damage data from a visual interpretation of high-resolution satellite images were used in combination with the tsunami numerical simulation to develop tsunami vulnerability curves called tsunami fragility curves. Tsunami

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features during inundation, such as inundation depth, current velocity and hydrodynamic force can be simulated by the numerical model. The tsunami fragility function can be constructed by combining the inspected damage data and simulated tsunami features using a statistical approach. The developed tsunami fragility curves for each location could be important tools for tsunami risk assessment against potential future tsunamis. However, applying tsunami fragility for future risk evaluation should be performed with care. The structural characteristics and behaviour of housing and buildings differ by country (Fig. 24). For example, an RC-frame building with brick walls is common in Southeast Asian countries. However, wooden walls are commonly used in Japan because of their light weight for reducing damage from earthquakes. These differences cause the tsunami damage characteristics to be different (Suppasri et al., 2011b).

Fig. 25. Examples of building damage in the case of the 2004 Indian Ocean tsunami in Thailand and the 2011 Tohoku tsunami in Japan
