How are Singapore and the rest of Southeast Asia affected by tsunami from the Manila Trench?

The 2004 Indian Ocean, 2010 Chile and 2011 Tohoku-Oki tsunami events have demonstrated the destructiveness of tsunami to both near and far-field communities. Globally, many coastal cities have started to place more emphasis on preparing for these rare but potentially catastrophic events by developing probabilistic tsunami hazard assessments (PTHAs). Previous work in the region has identified the Manila Trench to be a potential tsunami source within the South China Sea. Here we model the wave propagations from heterogeneous fault slips, for magnitudes ranging from 7.4 to 8.4, along the southern segment of the Manila Trench, and develop hazard curves for 52 sites in equatorial Southeast Asia. Our results show that the hazard, based on wave heights and arrival times, is variable on both the regional and local scales. Amongst the Southeast Asian countries studied, the Philippines and Vietnam are identified to be most at risk, with high mean peak nearshore amplitudes and short wave travel times. The least impacted countries include Singapore, western Malaysia, Indonesia (excluding the Natuna Islands), Thailand and Cambodia. Although the hazard for Singapore appears to be low, tides and wave run-up are not accounted for in this regional study. To address this we re-model the worst-case scenario adjusting for the highest astronomical tides and bottom friction. Our preliminary results show that Singapore can experience maximum wave heights up to 0.15 m. The relatively low wave heights yield low maximum inundation distances and suggest that the tsunamigenic hazard in Singapore is low. Hazard from tsunami currents, however, remains undetermined at this stage.