Observations from the 2009 Samoa Tsunami: Damage Potential in Coastal Communities

Abstract

The September 2009 tsunami devastated the Samoan Islands. Damages observed in eighteen coastal villages following this natural disaster are presented. Using observations and idealized numerical simulations, four main conclusions are drawn regarding tsunami damage patterns in these communities. First, for coastal regions with steep terrain, damage to structures is a function of distance from the shoreline, elevation, construction, and topographic conditions. Second, in those villages where inundation is confined by topography (steep bluffs or mountains), damage is more severe. Third, when inundation is unconfined by topography, damage potential (capacity to cause damage, should buildings of a certain construction be present) in these villages increases with decreasing mean topographic slope. Fourth, run-up height and flood elevation may not be the best indicator of damage potential in these villages, which are characterized by irregular topography. Finally, a damage potential formulation is presented which considers both hydrodynamic loading and topography. The proposed damage potential formulation can be used as a tool to help governments, emergency planners, and forecasters to prioritize hazard mitigation initiatives, evacuations, and detailed tsunami forecast simulations.