WAGIS2017

A method to translate video output from a NOAA tsunami wave model to produce wave run-up projections along coastlines is presented.

Coastal regions of the Pacific Northwest have long been aware of the threat posed by tsunamis.  Only recently have the communities surrounding Puget Sound realized the damage that could result from tsunamis generated by large subduction earthquakes along any of the mapped faults in or near Washington State. Snohomish County collaborated with NOAA to provide our emergency management department with inundation maps based upon NOAA’s modeling of a magnitude 7.3 earthquake along the Seattle Fault, which lies below Seattle, Washington.

NOAA provided Snohomish County with video animations of the model output showing the spatial extent of the wave propagation along with color coded wave amplitudes. Snohomish County staff conducted a series of image analyses and GIS processing tasks to extend the model results to include areas of potential wave run-up inundation and to provide estimates of value for structures subject to damage.  Specific tasks and analyses included; video to image conversion, maximum wave height extraction, projection of maximum wave height to a digital elevation model (DEM), calculating location-specific wave run-up data for all coastal areas using Klettner’s (2012) method, and mapping the inundation area.  After identifying the wave run-up areas, parcel data was used to estimate the potential economic impacts of the tsunami.

The method developed in this study can be applied to other areas where tsunami simulation video and accurate coastline data are available.