(AP)—Volunteers who patrol California beaches for plastic, cigarette butts and other litter will be on the lookout this winter for debris from last year's monstrous tsunami off Japan's coast.
The March 2011 disaster washed about 5 million tons of debris into the sea. Most sank, leaving an estimated 1 1/2 million tons afloat. No one knows how much debris—strewn across an area three times the size of the United States—is still adrift.
Last week, the U.S. Coast Guard spotted a massive dock that possibly came from Japan on a wilderness beach in Washington state.
The West Coast is bracing for more sightings in the coming months as seasonal winds and coastal currents tend to drive marine wreckage ashore.
The National Oceanic and Atmospheric Administration recently received a $5 million donation from Japan to track and remove tsunami debris.
Debris from Asia routinely floats to the U.S. It's extremely difficult to link something back to the Japanese tsunami without a serial number, phone number or other marker.
Of the more than 1,400 tsunami debris sightings reported to NOAA, the agency only traced 17 pieces back to the event, including small fishing boats, soccer balls, a dock and a shipping container housing a Harley-Davidson motorcycle with Japanese license plates.
Charlie Plybon, Oregon's regional manager at the Surfrider Foundation, said the tsunami has raised beachgoers' awareness about marine debris plaguing the world's coastlines.
"There's a bit of tsunami debris fever. It's like an Easter egg hunt," said Plybon, who has been cleaning up the Oregon coast for over a decade. "People used to walk past debris. Now they want to be engaged."
Tsunami waves swamped a Japanese nuclear power plant and swept debris into the ocean, but health experts have said debris arriving on the West Coast is unlikely to be radioactive after having crossed thousands of miles of ocean. The debris field, which once could be spotted from satellite and aerial photos, has dispersed.
More than 18,000 residents were killed or went missing.
Volunteer Julie Walters has combed Mussel Rock Beach south of San Francisco for wreckage, but all she has found so far are wave-battered boat parts and lumber of unknown origin.
If she did find an object with a direct link, "I would find it quite intriguing that it made this incredible journey across the Pacific," said Walters, a volunteer with the Pacifica Beach Coalition. "It would also sadden me to think of the human tragedy."
Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.