An empty Japanese fishing boat drifting off the coast of western Canada could be the first wave of 1.5 million tons of debris heading toward North America from Japan's tsunami last March.

The wreckage from flattened Japanese coastal towns - including refrigerators, washing machines, televisions, roofs and fishing nets - is heading inexorably east across the Pacific and could arrive sooner than expected, according to the US National Oceanic and Atmospheric Administration.

"The early indication is that things sitting higher up on the water could potentially move across the Pacific Ocean quicker than we had originally thought," said Nancy Wallace, director of NOAA's Marine Debris Program, which had forecast the appearance of tsunami debris on North American shores only in 2013.

"Those higher-wind, quicker-moving items may actually be onshore much sooner - pretty much now."

On March 20, Canada's transport department spotted what it said was an empty Japanese fishing vessel 150 nautical miles south of the Queen Charlotte Islands, adjacent to the main coast of British Columbia.

The ship has been declared a hazard to shipping, but Canada has not said what, if anything, it will do with it. The country's Coast Guard said it will take action only if fuel spills from the ship, which is not likely.

The so-called ghost ship is the first major piece of evidence that Japanese tsunami debris is heading to the United States.

"It does confirm that debris generated by the tsunami will make landfall on the west coast of North America," said Nicholas Mallos, a conservation biologist and marine debris specialist at the independent Ocean Conservancy, which monitors the problem of Ocean trash.

"However, what the quantity of that debris is and what it looks like are questions that are still largely unanswered."

The NOAA, which is part of the US Department of Commerce, initially expected to find debris hitting the northern Hawaiian islands this winter and moving slowly onto Alaska, Canada and the US West Coast next year.

But those forecasts, made shortly after the tsunami on limited historical current and wind models, are proving inaccurate.

The agency is finding that debris is moving north of Hawaii's northernmost points, and making its way to the continent ahead of schedule, said Wallace. It is now tweaking its forecast to account for new material, such as analysis of recent oil spills and how wind will affect some objects more than others.

"Right now, we are trying to get that methodology of the new models validated by peer review experts," she said.

Wall of water

A magnitude 9.0 earthquake off Japan's northeast coast on March 11, 2011, triggered a 23-meter wall of water that flattened waterfront towns, killing 16,000. Three thousand people are still unaccounted for.

US authorities were immediately aware that the clockwise circulation of the Pacific's northern waters would deliver some remnants of that destruction. But the extent and composition of the debris is unclear. For about a month after the tsunami, a "debris field" was visible by satellite. It has since been dispersed, making it impossible to track, except from vessels.

The Japanese government has estimated that debris from the coastal prefectures of Iwate, Miyagi and Fukushima totaled 5 million tons. Of that, it says, 70 percent would have sunk quickly onto the coastal seabed of Japan, but the other 30 percent, or 1.5 million tons, would have floated.

It is impossible to say how much of that will break up and sink along the way and how much will end up on American beaches.

Reuters