But the giant wall of water appeared to have lost much of its energy as it roared thousands of miles (km) across the Pacific Ocean toward North America, according to initial reports from officials in the United States, Mexico and Canada.
"The models are showing that the waves are dying down and so hopefully this event will be over in two to five hours," Laura Furgione, a senior official at the U.S. National Oceanic and Atmospheric Administration, told reporters in a phone call at 2 p.m. EST (1900 GMT).
With the tsunami still poised to strike South America's coastline, Chile said it would evacuate flood-prone areas. The country was hit by a magnitude 8.8 quake and ensuing tsunamis a year ago that killed more than 500 people.
The waves are expected to reach mainland Chile around midnight local time (0300 GMT on Saturday). The government also upgraded the tsunami alert for Chile's remote Easter Island.
Waves crashing ashore along the California coast were larger than normal, but only the town of Crescent City, near the California border with Oregon, and Santa Cruz, 72 miles (115 km) south of San Francisco, suffered any real damage.
About 35 boats and most of the harbor docks were damaged in Crescent City, where waves were more than 6 feet (2 metres), while Santa Cruz 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.
Thousands of residents were evacuated along the California coast, including 6,000 near Santa Cruz, before the tsunami made landfall, said Jordan Scott, spokesman for the California Emergency Management Agency.
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
In Hawaii, 3,800 miles (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 U.S. Navy ordered all warships in Pearl Harbor to remain in port to support rescue missions as needed.
Civil defense sirens blared statewide, starting shortly before 10 p.m. local time, and police with bullhorns urged residents near shore to 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 to an advisory.
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 U.S. states and territories, the White House said.
CHILE RESIDENTS ALERT
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.
The area at risk includes the Galapagos Islands -- a popular tourist destination known for its wildlife, including endangered species, that inspired British naturalist Charles Darwin's evolution theory in the 19th century.
State oil company Petroecuador halted product shipments.
Peruvian officials said they were waiting until late afternoon to decide if they would order evacuations from low-lying coastal areas such as the port city of Callao.
Many ports along Mexico's western coast were 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 the Canadian province of British Columbia advised residents to evacuate marinas, beaches and other low-lying areas, but officials there said the waves were minimal.