Tsunami Impact Assessment for Unalaska, AK

Being the most populous area in the Aleutians, Unalaska is considered as one of Alaskan coastal communities with high potential for tsunamis. As part of NOAA's Short-term Inundation Forecast for Tsunami (SIFT), a Stand-by Inundation Model (SIM) based on the MOST model is applied in this study to assess the tsunami impact for Unalaska. The model validation using historical tsunami events show excellent agreement between the model computation and observations, which gives rise to the accuracy of the inundation model. This study provides inclusive tsunami impact assessment for Unalaska, AK subject to a total of 2681 distant and local tsunamis scenarios in the Pacific at different level of earthquake magnitude M_w 7.5, 7.8, 8.2, 8.7 and 9.3. This study also investigates the impact caused by the hypothetical scenarios initiated in Unalaska gap and Shumagin gap at different level of earthquake magnitude M_w 7.5, 8.0, 8.5, and 9.0. The computational maximum tsunami runup suggests the current definition of Tsunami Safe Zone in Unalaska, areas above 50ft (~15m), is conservative.