Thousands of people fled their homes along the Pacific coast of North and South America on Friday as a tsunami triggered by Japan's massive earthquake reached the region but spared it from major damage.

The giant wall of water lost much of its energy as it roared thousands of miles across the Pacific Ocean, although many governments took no chances, ordering large-scale evacuations of coastal areas, ports and refineries.

The West Coast and Alaska Tsunami Warning Center downgraded the situation in California from a tsunami "warning" to an "advisory," and fears of a catastrophe proved unfounded.

Despite the power of Japan's biggest-ever earthquake that killed at least 1,300 people, the tsunami waves were relatively benign as they rolled into the Americas, causing only isolated flooding.

"Mexico is no longer in danger," Mexican President Felipe Calderon said in a post on his official Twitter account.

Ecuador's Galapagos Islands, a wildlife sanctuary and popular tourist spot, suffered some damage to infrastructure. and several California harbors were hit. Chile, which was hit by a magnitude 8.8 quake and ensuing tsunamis a year ago that killed more than 500 people, appeared to be unscathed.

Residents in northern Chile said the coast was calm some time after waves had been expected to make landfall.

Peru, which evacuated thousands, was also largely unaffected.

About 35 boats and most of the harbor docks were damaged in Crescent City near the California border with Oregon, where waves were more than 6 feet (2 metres). Santa Cruz south of San Francisco sustained about $2 million in damages to docks and vessels, emergency management officials said.

Rescue services were searching for a 25-year-old man who was swept out to sea while standing on a sandbar at the mouth of the Klamath River in California.

The port of Brookings-Harbor, the busiest recreation port on the Oregon coast, was largely destroyed, said operations manager Chris Cantwell. "Right now we are in the middle of a big mess," he said. "The surge pulled some (boats) out to sea, about a dozen sank and we've got boats everywhere sitting on top of one another and all over the place."

Sirens blare

In Hawaii, 6,200 km from Japan, the main airports on at least three of the major islands - Maui, Kauai and the Big Island of Hawaii - were shut down as a precaution, and the US Navy ordered all warships in Pearl Harbor to remain in port to support rescue missions as needed.

Civil defence sirens blared statewide, starting shortly before 10pm local time, and police with bullhorns urged residents near shore to seek higher ground.

No injuries or property damage were reported after a series of four tsunami waves hit the Hawaiian island of Oahu, said John Cummings, a spokesman for emergency management in Honolulu. The tsunami warning for Hawaii was later downgraded.

President Barack Obama, a native of Hawaii, was notified of the massive Japanese quake at 4 a.m./0900 GMT and instructed the Federal Emergency Management Agency to be prepared to help affected US states and territories, the White House said.

Ecuador took extreme precautions after President Rafael Correa declared a state of emergency across the Andean nation on national television and urged residents to move inland.

Oil firm Petroecuador also halted production, but navy officials said on Friday night that the risk of danger had passed.

Many ports along Mexico's western coast closed, including Los Cabos and Salina Cruz in southern Oaxaca, the only oil-exporting terminal on the country's Pacific side.

Mexican officials said high waves had hit the northwestern Pacific coast but there were no reports of damage.

Authorities in Canada's British Columbia advised residents to evacuate marinas, beaches and other low-lying areas, but officials there said the waves were minimal.