Characteristics of tsunami inundation area in the eastern part of Sri Lanka due to the 2004 Sumatra earthquake observed in high-resolution satellite images

摘要

It is important for efficient post disaster management to develop a methodology to identify affected areas from remote sensing data. Inundation of the tsunami generated by the 2004 Sumatra earthquake caused severe damage in coastal areas in Sri Lanka, located 1,500km away from the epicenter. As the preliminary stage for extraction of the tsunami inundation areas from high-resolution satellite images, the characteristics of the pre- and post-event images in Batticaloa city, the eastern part of Sri Lanka, are examined. Normalized difference vegetation index (NDVI) calculated from the images is utilized since the densities of the vegetations in the affected area are decreased due to the tsunami inundation. The distribution of the difference of NDVI between pre- and post-event images is compared with the actual inundation area observed in the field survey. The result shows that the difference in the inundation areas shows larger than that in the non-inundation areas. The areas that NDVI is remarkably decreased after the event are extracted as the inundated areas. The distribution of the extracted areas correlates with the actual inundation area.