Scenario-based tsunami hazard assessment for the coast of Vietnam from the Manila Trench source

• This paper assesses the tsunami impact from Manila Trench source to Vietnamese coast.
• A new source model was developed for the Manila Trench megathrust.
• The COMCOT model was applied to simulate 100 tsunami scenarios for warning purpose.
• Results of the worst case scenario (Mw = 9.3) are used for tsunami hazards assessment.
• Highest tsunami threat is concentrated along the coast of Central Vietnam.

This paper assesses the impact of tsunamis in the East Vietnam Sea potentially originated from a giant rupture along the Manila Trench to the Vietnamese coast. Tsunami heights and arrival times to the major forecast points along the Vietnamese coast are computed using COMCOT model. The results of the worst case scenario (Mw = 9.3) and two extreme scenarios were used to assess the tsunami hazards. The simulation results show that Vietnamese coast can be divided into three parts with different levels of tsunami hazard. The highest threat exists along the coasts of Central and North-Central Vietnam, from Quang Binh to Ba Ria – Vung Tau provinces, with maximum wave height of 18 m observed near Quang Ngai coast, and a tsunami would reach this coastline in two hours at the earliest. The northern coastal zone of Vietnam has lower tsunami hazard. In the worst case scenario, maximum amplitudes of tsunami waves at Hai Phong sea port and Nam Dinh city, North Vietnam, are 3.5 m and 3.7 m, respectively, while the travel times to these sites are much longer, over 8 h. The southern coastal zone of Vietnam has very low tsunami hazard. In the worst case scenario, the maximum amplitude at Ca Mau is 0.12 m, while the travel time is over 10 h.