Since the 2004 Indian Ocean tsunami, various methods for assessing and reducing the risk from tsunamis to coastal communities have been developed. The goal of these methods is to first determine which areas may be at risk from the impacts of tsunamis and then to provide real-time forecasts for coastal locations when a tsunami wave is propagating through the open ocean. Coastal forecasting of tsunamis in both research and operational contexts is evolving as refinements are made to earthquake sources, bathymetry, and propagation and inundation models. The types of models and data requirements vary considerably depending on the geographic scale of the output coastal forecast. For example, large scale regional assessments are often first performed to determine the areas at highest risk from tsunamis for further evaluation. Small scale assessments can then be performed for individual communities in these high risk areas. Forecasts of tsunami risk down to the tax parcel level can be developed using a combination of modeling output, information on land cover, land use, building composition, census information and fragility curves. The output from both large and small scale studies are useful for tsunami hazard planning, mitigation and developing strategies for the long term resiliency of coastal communities.

In this paper, we will examine the range of scales used to forecast tsunami risk at the regional and local levels. We will discuss several approaches to the problem and how geospatial technologies enable scientists, community planners, and the general public to integrate the vast amount of available data, model output and results from tsunami science research to ultimately make informed decisions.