Multi-Hazard Resilience Assessment of a Coastal Community Due to Offshore Earthquakes

It has been observed in different parts of the world that offshore earthquakes occurred in coastal regions were followed by tsunamis and catastrophic damages due to cascading effects. In this paper, an innovative methodology for the estimation of direct damage losses and resilience for a given community is presented. It combines two existent methodologies, including both earthquake and tsunami hazards. In detail, fragility functions related to earthquake intensity, ground failure and tsunami inundation are combined with regional hazard data to estimate damages and direct economic losses of buildings and bridges. The coastal city of Seaside in Oregon has been used as a case study and as one of the most vulnerable town in the Pacific North United States due to the proximity of a nearfield Cascadia Subduction Zone. The results indicate that, when the earthquake and the subsequent tsunami inundation are considered together, there is an overwhelming increase in the loss estimates in comparison to the case when the tsunami is separately considered.