When will the debris from the tsunami in Japan reach the U.S.?
Many variables affect where the debris will go and when. Items will 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 shows that some buoyant items first reached the Pacific Northwest coast during winter 2011-2012. More debris is likely still dispersed north of the Main Hawaiian Islands and east of Midway Atoll.
The model gives NOAA an understanding of where debris from the tsunami may be located today, because it incorporates how winds and ocean currents since the event may have moved items through the Pacific Ocean. This model is a snapshot of where debris may be now, but it does not predict when debris will reach U.S. shores in the future. It's a "hindcast," rather than a "forecast."
However, throughout the winter of 2012-2013, seasonal changes in North Pacific winds and currents caused marine debris of mixed types to wash ashore on western coastlines of North America. Hawaii also received mixed debris during this time, since debris likely traveled west toward the Main Hawaiian Island with ocean currents.
The model also takes 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).