Modeling scenarios of earthquake-generated tsunamis for the Vietnam coasts

Modeling a hazard scenario has the main purpose to assess the maximum threat expected from a studied phenomenon in a certain area and to give specific directives to the local authorities in order to prevent and mitigate serious consequences on the population, the infrastructures and the environment. To build scenario-based tsunami hazard maps for a specific coastal area one has first to characterize the seismic sources (or other tsunamigenic events, not considered in this study) and select the earthquake scenarios that can drive the hazard. By means of the modeling we then calculate the maximum amplitude of the vertical displacement of the water particles on the sea surface and the travel time of the maximum amplitude peak, since they are the most relevant aspects of the tsunami wave and also are the only characteristics always recorded in the chronicles and therefore in catalogues. In this work we have used this approach to compute earthquake generated tsunami hazard along the Vietnam coasts. The results of our calculations suggest that a tsunami with maximum amplitude up to ten meters can be expected also in the South China Sea, in agreement with a number of historical events reported in the catalogues. Considering the low level of monitoring of the South China Sea and the advanced anthropic setting of the Vietnam coasts, and their high level of vulnerability, we hope that the results can be used as a preliminary knowledge basis to: design early warning systems, reduce tsunami risk and plan land-use for the Vietnam coasts.