Assessment of Nearshore Hazard due to Tsunami-Induced Currents

Abstract:

The California Tsunami Program in cooperation with NOAA and FEMA has begun implementing a plan to increase tsunami hazard preparedness and mitigation in maritime communities (both ships and harbor infrastructure) through the development of in-harbor hazard maps, offshore safety zones for boater evacuation, and associated guidance for harbors and marinas before, during and following tsunamis. The hope is that the maritime guidance and associated education program will help save lives and reduce exposure of damage to boats and harbor infrastructure. Findings will be used to develop maps, guidance documents, and consistent policy recommendations for emergency managers and port authorities and provide information critical to real-time decisions required when responding to tsunami alert notifications.

The initial goals of the study are to (1) evaluate the effectiveness and sensitivity of existing numerical models for assessing maritime tsunami hazards, (2) find a relationship between current speeds and expected damage levels, (3) evaluate California ports and harbors in terms of tsunami induced hazards by identifying regions that are prone to higher current speeds and damage and to identify regions of relatively lower impact that may be used for evacuation of maritime assets, and (4) determine ‘safe depths’ for evacuation of vessels from ports and harbors during a tsunami event. We will present details of a new initiative to evaluate the future likelihood of failure for different structural components of a harbor, leading to the identification of high priority areas for mitigation. This presentation will focus on the results from California ports and harbors across the State, and will include feedback we have received from discussions with local harbor masters and port authorities. To help promote accurate and consistent products, the authors are also working through the National Tsunami Hazard Mitigation Program to organize a tsunami current model benchmark workshop.