Update June 6, 2012: Video: Huge Dock washed ashore on Oregon Coast is Japan Tsunami Debris
Original post
Good article from Paul Rogers in the Merc today on the debris from the Japanese tsunami slowly but surely making its way across the Pacific. The mass of refuse is expected to hit the west coast in late 2013 or early 2014.
The debris is moving east at roughly 10 miles a day, and is spread over an area about 350 miles wide and 1,300 miles long -- an area roughly the size of California -- (Seattle oceanographer Curtis) Ebbesmeyer estimates, with the leading edge approaching the international date line. While lots of the material will break up and sink, some will not, he said...
(N)obody knows for sure the exact area where the debris is spread or its density. And nobody knows what is still floating, what has sunk, or what may be lurking just below the surface. That's because estimates are based on computer models of currents and winds, rather than actual observations from scientists in boats and planes. After ships with the Navy's 7th Fleet reported and photographed the debris, researchers with the National Oceanic and Atmospheric Administration (NOAA) in Hawaii tracked the refuse with satellites for a month after the March 11 quake and tsunami. But by April 14, as it spread over a wider area, it could no longer be detected with the resolution of the satellites that NOAA uses. Full article
Here's a computer simulation projecting the debris path, from the International Pacific Research Center, followed by a legend from the Merc indicating the density of the debris.