The body of a US man swept away by Japan's tsunami when it hit California has been found on a beach, officials said Tuesday, a month after the disaster.

The corpse of Dustin Douglas Weber, who disappeared when waves from the March 11 quake and tsunami hit the California coast, was found some 440 miles (700 kilometers) north in neighboring Oregon state.

"It was found by some passers by on the Oregon coast beach," said Eugene Gray of the western US state's Medical Examiner's Office, adding that dental records had helped identify him.

Weber, a native American, was swept off his feet near Klamath in northern California, just south of Crescent City, where the tsunami threw boats on top of each other after traveling some 5,000 miles (8,050 kilometers) across the Pacific.

The 25-year-old's body was found on April 2 near Astoria on the Oregon coast, said Gray, adding that the cause of death would be listed as drowning and the body would be returned to the family.

"The next of kin have been contacted and are making arrangements," he said.

Waves of eight feet (2.4 meters) crashed ashore on the California coast up to 12 hours after the 9.0-magnitude quake that killed more than 13,000 people, left over 14,500 missing and triggered a major nuclear crisis.