NASA put up an image and write up of tracking probable tsunami debris paths earthobservatory.nasa.gov from the Tohoku Tsunami.
Keep in mind that this is not the first time that tsunami material from Japan has traveled across the Pacific to the coast of Washington. The flotsam of tsunamis, huge storms and damaged boats and simply garbage has traveled across the Pacific Ocean to our coast for thousands of years and has left some interesting legacies.
For many years glass floats used with Japaneses fishing nets adorned many Washington and Oregon coastal homes as greatly prized beach comber finds. But try to picture the arrival of debris if you were living on the Washington coast say 500 years ago. A striking indicator of this was encountered at archaeological excavations on the outer coast where First Nations peoples were utilizing metal fishing hooks and other decidedly non local implements prior to European contact.
My favorite story of debris was the arrival of a Japaneses boat that washed up on what is now the northern Washington coast in 1834 after drifting across the entire Pacific. Three of the survivors of that wreck were initially enslaved by the Makah, but were then released to the Hudson Bay Company at Fort Vancouver (now Vancouver, Washington). This event has led to an often repeated story of a young Ranald MacDonald meeting the three Japanese and this meeting being the inspiration for MacDonald having himself cast-a-way on purpose on the Japanese coast prior to the opening of Japan. However, MacDonald's meeting with the Japaneses cast-a-ways is not accurate and has been described as a story that “settled like sludge into the historical record”. That said, MacDonald is credited for his role in the opening of Japan; a monument at his grave in Toroda, Washington near the U.S.-Canadian border in the highlands of north central Washington has a matching monument in Nagasaki, Japan.
Hudson Bay Company Chief Factor John McLoughlin was interested in the Japanese cast-a-ways as potentially helpful for trade relations with Japan. One of the cast-a-ways ultimately aided England in establishing trade relations with Japan. (More Here)