A huge dock torn from a Japanese port by March 2011 tsunami has washed up in the US state of Oregon – 8,050 km (5,000 miles) across the Pacific.
The 20m-long (66ft) concrete dock weighing 165 tons was spotted on Agate beach, south-west of Portland.
A Japanese consulate official said a commemorative plaque showed it had come from the fishing port of Misawa.
Radiation checks proved negative, but scientists say invasive species foreign to the area may have hitched a ride.
A huge dock torn from a Japanese port by March 2011 tsunami has washed up in the US state of Oregon
A starfish native to Japan was among the marine life still clinging to the structure, Oregon Department of Parks and Recreation spokesman Chris Havel was quoted as saying by the Associated Press news agency.
“This is tsunami debris, not just from Japan, but from the tsunami itself,” Chris Havel said.
Oregon police have now been deployed to keep people from climbing on the dock, which was first mistaken by local residents for a barge.
Misawa lost four docks during an earthquake and resulting tsunami on 11 March 2011. Two docks are still missing.
This April, the US Coast Guard used cannon to sink a crewless Japanese ship that drifted to Alaska after the tsunami.
A month later, a Japanese owner of a Harley-Davidson motorbike swept away by the tsunami was amazed to find out that it had been washed up inside a container on a beach in Canada – about 6,400 km away.
Japanese scientists estimate that some 20 million tons of debris were generated by the earthquake and the incoming rush of water.
Most would have stayed on land, and a fair proportion pulled out to sea would have sunk rapidly. But it is possible a million tons of debris is still afloat.
Nearly 16,000 people were killed by the quake and tsunami in Japan.
The crewless Japanese ship that drifted to Alaska after the 2011 tsunami has been sunk by the US Coast Guard.
The coast guard earlier said they would hold off scuttling the Ryou-Un Maru after a Canadian fishing boat claimed salvage rights.
But a Canadian official later said that the Bernice C had been unable to tow the 200 ft (61 m) Japanese “ghost ship”.
The US Coast Guard has used cannon to sink the boat, which had no lights or power and was viewed as a danger to other ships.
It was thought to be at the vanguard of a stream of tsunami debris that has been drifting east since last year’s disaster hit Japan.
The Ryou-Un Maru was first spotted off the coast of Canadian British Columbia on 23 March.
The vessel was moving at about 1 km/h in a maritime transport corridor that separates US and Canadian waters.
It was adrift about 195 miles from Sitka, Alaska, when it was sunk, officials said.
The US Coast Guard has used cannon to sink the Japanese ghost ship that drifted to Alaska after the 2011 tsunami
Chief Petty Officer Kip Wadlow told AP news agency that a cutter was used to fire cannon at the abandoned ship, which burst into flames and took on water.
After a few hours, larger ammunition was used to complete the job, he said.
A Hercules C-130 air crew was ready to participate in the operation, broadcasting to mariners and air traffic to alert them and help clear the surrounding area before the demolition of the ship began.
CPO Wadlow said it would be too expensive to try to salvage the ship, and too dangerous to put anyone on board.
The ship may have carried more than 7,500 litres of diesel fuel, officials said.
The Ryou-Un Maru, a shrimping boat, has been traced to the Japanese island of Hokkaido.
Alaskan Senator Mark Begich suggested that the boat’s owner had been identified, but the owner did not want the vessel back.
On 11 March 2011, a 9.0-magnitude earthquake hit Japan, triggering a tsunami that swamped a power station, prompting the worst nuclear crisis since the 1986 Chernobyl disaster.