Mapping of historical tsunamis in the Indian and Southwest Pacific Oceans

Asia and Southwest Pacific Oceans experienced considerable effects due to tsunamis, including the Indian Ocean event in 2004, many local events along the Indonesian coast in 2005, 2006 and 2010, and the tsunami in Japan in 2011. This study started by collecting an assessment of the earthquake return periods and their tsunamigenic ratios. Previous studies show that recurrence of Mw 7.5, 8.0, 8.5 and 9.0 earthquakes are 20–50, 60–120, 200–300 and 450–650 years and Mw 7.5 and Mw 8.0 earthquake has potential of 0.5 and 0.8 to generate a tsunami. Historical tsunamis were selected to characterize the tsunami hazards in this region. A total of 30 tsunami scenarios were selected from 110 possible historical events that occurred within the last 400 years for a far-field tsunami simulation. The simulation calculated the maximum tsunami heights along shoreline that were subsequently evaluated based on reported survey data. Simulated results showed that Japan faced the highest levels of local tsunami impacts, followed by Indonesia, the Philippines and Papua New Guinea. Local tsunamis were not observed in Thailand, Sri Lanka and India, although these areas were greatly affected by the devastating event in 2004. China and Taiwan were affected by local tsunamis and tsunamis that occurred in Japan. Other countries in the South China Sea, such as Vietnam, Malaysia, and Singapore, had comparatively small impacts due to their geographical locations. The maximum tsunami height map developed here will improve our understanding of the general impacts of historical tsunamis in Asian and Southwest Pacific countries.