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Tsunamis: What can the ocean floor tell us about the next disaster?

March 7, 2017
A digital elevation model (DEM) image for  the Society Islands, French Polynesia, in the South Pacific. This DEM was built for the NOAA Tsunami Warning Centers to aid in forecasting throughout the Pacific Basin.

Tsunamis – huge ocean waves generated by sudden movements in the seafloor, landslides, or volcanic activity – have killed hundreds of thousands of people worldwide and caused billions of dollars in damage. They are equal opportunity destroyers: No coastal area in the world is entirely safe from them.

In the deep ocean, tsunami waves may only be a few inches high and often go undetected. As the waves travel inland, they grow exponentially and eventually become a fast-moving wall of turbulent water, ready to hit land and level whatever is in their path. How tsunami waves behave – how far and fast they travel – is influenced by the ridges and valleys of the ocean floor and of our coastlines.

Scientists at NOAA are developing computer models aimed to take the surprise out of tsunamis.

Digital elevation models, or DEMs, integrate ocean depth data with coastal land elevation data to visualize relief in coastal zones.

This digital elevation model image for Barkley Sound on the west coast of Canada’s Vancouver Island shows  the entrance to the Port Alberni Inlet.
This digital elevation model image for Barkley Sound on the west coast of Canada’s Vancouver Island shows the entrance to the Port Alberni Inlet. (NOAA)

“These detailed coastal relief models provide a framework that allows the Tsunami Warning Centers to more accurately predict the tsunami impact in coastal communities and ultimately save lives from better warnings,” says Kelly Stroker, Coastal Hazards Team Lead for NOAA’s National Centers for Environmental Information (NCEI).

High-resolution DEMs are a crucial part of the U.S. Tsunami Forecast and Warning System. Scientists have completed more than 200 models for U.S. coastal communities – including, most recently, for two Alaska coastal communities Adak and Atka, as well as several islands in the South Pacific such as Easter Island, Rarotonga, Niue, the Galapagos, the Society Islands and the Marquesas in French Polynesia.

A perspective of the digital elevation model of Atka, Alaska.
A perspective of the digital elevation model of Atka, Alaska. (NOAA)

Taking the guesswork out of where the waves will go

Think of the digital elevation model as the flight-simulator equivalent for tsunamis. Here’s how it works:

  1. When NOAA scientists complete a DEM, they deliver it to NOAA’s Center for Tsunami Research in Seattle where it is incorporated into tsunami models. These models simulate offshore earthquakes, the resulting tsunami movement across the ocean, and the magnitude and location of coastal flooding caused when a tsunami reaches the shore.

  2. Armed with these simulation results, NOAA's tsunami warning centers are then able to forecast flooding in the event of an earthquake-generated tsunami. Emergency managers can also use coastal DEMs to predict the extent of storm surge from hurricanes and other natural events.

Saving lives starts with data-sharing

The DEM team at NCEI draws on its vast archive of data about the ocean floor (known as “bathymetry” data) collected for navigation and ocean resource management, as well as data from other federal agencies like U.S. Geological Survey, U.S. Army Corps of Engineers, NASA, academia and nonprofit organizations. Visit NCEI to learn more about digital elevation models.