Tsunami Debris Modeling

When will the debris from the tsunami in Japan reach the U.S.?

Many variables affect where Japan tsunami marine debris goes and when. Items sink, disperse, and break up along the way, and winds and ocean currents constantly change, making it very difficult to predict an exact date and location for the debris’ arrival on our shores.

A NOAA modeling effort, the NOAA GNOME model, showed that some buoyant items first reached the Pacific Northwest coast during winter 2011-2012.

This model gave NOAA an understanding of where debris from the tsunami may be located, because it incorporated how winds and ocean currents since the event may have moved items through the Pacific Ocean. The model was a snapshot of where debris may currently be, but did not make future predictions for when debris would reach U.S. shores. It worked as a "hindcast," rather than a "forecast."

The model also took into account the fact that winds can move different types of debris at different speeds. For example, wind may push an upright boat (large portion above water) faster than a piece of lumber (floating mostly at and below the surface).

Beginning in 2015, NOAA discontinued regular updates to the NOAA GNOME model. While this effort was useful in estimating debris movement and distribution initially, in the years since the tsunami, the debris has become widely dispersed across the Pacific and more difficult to model accurately. On any given day, additional marine debris from the tsunami could arrive on shorelines in Alaska, the West Coast, and Hawaii. If there is a need, NOAA will consider further modeling efforts.