TSUNAMI INUNDATION MODELING: SENSITIVITY OF VELOCITY AND MOMENTUM FLUX TO BOTTOM FRICTION WITH APPLICATION TO BUILDING DAMAGE AT SEASIDE, OREGON

Abstract

We examine the sensitivity of three different tsunami inundation numerical models using various friction terms. We use the model output to examine the probabilistic damage levels using fragility curves applied over a community scale and resolved at the scale of individual tax lots for Seaside, OR. With this work, we estimate the inundation hazard using the "500 year" tsunami originating from a Cascadia Subduction Zone earthquake and then compare the maximum surface elevation, velocity, and momentum flux results across the three models. We find a larger variation in the velocities and momentum fluxes when varying model types and friction coefficients; surface elevation variations are not as large. We also find that absolute velocity and momentum flux are more sensitive to friction factors rather than model type, while surface elevation varies with model type. For the fragility curve analysis, we consider flow depth, velocity, and momentum flux as the intensity measure to estimate the probability of a certain damage level based on the known structure type and characteristic tsunami intensity. We examine the sensitivity of damage levels to various fragility curves, using different intensity measures, and we find that velocity and momentum flux curves provide a more realistic estimate of damage.