Informing Tsunami Risk with Average Annualized Losses

Recent events in the United States and around the world show how tsunamis can cause substantial loss of life and property damage. To better understand the potential impacts from future tsunamis striking the nation’s coastal states and territories, the Federal Emergency Management Agency partnered with the United States Geological Survey; the National Oceanic and Atmospheric Administration; and the National Tsunami Hazard Mitigation Program (the program) collaborated together and published FEMA P-2426, “Estimated Average Annualized Tsunami Losses for the United States“.

The Estimated Average Annualized Building and Population Losses from Earthquake-generated Tsunamis in the United States study by the agency and its partners is a first-of-its-kind assessment. To estimate building loss, the agency used point-level building data from the United States Army Corps of Engineers National Structure Inventory, as well as state and territory hazard data. The agency used Hazus 6.1 to estimate building losses based on estimated replacement values for each scenario. To estimate population fatalities among residents, the agency leveraged a United States Geological Survey study that combined residential data from the 2020 Census with a National Structure Inventory dataset, state and territory hazard data, and pedestrian-evacuation modeling. The study used estimated return period data to annualize findings on building and population loss.

The data and results from the study has been published in a number of formats. You can explore the study through any of the following:

• The Tsunami Loss Viewer lets you explore the results in a user-friendly, map-based tool on ArcGIS Online. The tool provides average annualized, probabilistic, and individual scenario-level loss results at the county and Census tract levels. You can also download the results in a number of formats on the accompanying resources page.
• The Hazus Loss Library offers data packages you can download for each of the study’s analyses. These data packages include the tsunami hazard data, national exposure data, and building loss results. Pre-average annualized input building loss data are sorted by location and type of analysis; you can download them to customize for your own assessments. To learn more about the library and how to download the data, check out the How To Use the Hazus Loss Library guide.
• The P-2426 Technical Report, P-2426 Estimated Average Annualized Tsunami Losses for the United States, describes the study’s methodology and offers further insights into some of the results.
• The Average Annualized Tsunami Loss Data Release is the basis for the study. It includes all of the input and average annualized loss data.
• The Tsunami Evacuation Study Journal Article by the United States Geological Survey is a peer-reviewed article that interprets the residential population loss results.
• The Tsunami Evacuation Study Data Release by the United States Geological Survey is the basis for population loss results of the study. It includes estimates for the residential populations’ potential to evacuate.