There's an animation somewhere I saw on the web, of the debris field's predicted path. It was created shortly after the initial earthquake. The main body of debris disperses or sinks long before reaching the West Coast and much of it eventually joins the big swirling plastic garbage patch.
The Great Pacific Garbage Patch
Also known as the Pacific Trash Vortex, the Great Pacific Garbage Patch is an area of floating trash estimated to be in excess of 600,000 square miles, or twice the size of the state of Texas, and weighing 3.5 million tons.
Approximately 80% of the debris within the Garbage Patch comes from land, washing down from rivers and storm drains, or being swept off beaches by tides. The remaining 20% is from cargo containers that fall from oceangoing ships and spill their contents. Floating trash, the vast majority of which is plastic, is captured by rotating ocean currents and accumulates within the North Pacific Gyre.
There is a similar phenomenon, the Atlantic Garbage Patch, occurring in the Sargasso Sea between Bermuda and the Azores, in an area known as the North Atlantic Subtropical Gyre.
Read more:
The Great Pacific Garbage Patch: Facts on the Garbage in the Sea