People fled their homes in parts of northern California on Friday as a tsunami triggered by the massive earthquake in Japan began hitting the West Coast after rolling through Hawaii.
Initial reports from U.S. civil defense officials and residents of coastal communities suggested the force of the tsunami, a giant wall of water, had dissipated as it sped across the Pacific Ocean toward North America.
Tidal surges in the Hawaiian island chain were generally little higher than normal, officials said, and there were no reports of injuries or severe inland property damage.
An Obama administration official said Hawaii appeared to be out of major danger, but there was still some risk to the U.S. West Coast.
"I think the enormous fears that were there hours ago, for some of us hours ago, has diminished greatly, which is quite a relief for all of us," White House chief of staff Bill Daley said.
"There's always the possibility that something may happen after, so people are watching it now," he added.
Craig Fugate, administrator of the Federal Emergency Management Agency, was more cautious. "The problem is you're never sure until the waves come in," he told CNN.
The massive 8.9 magnitude quake in Japan triggered tsunami warnings for most of the Pacific basin. Advisories or warnings were in effect from Canada all the way down the Pacific coast of South America.
Canada advised local authorities in parts of British Columbia to evacuate marinas, beaches and other areas below the normal high tide mark.
A spokesman for California's state emergency agency said the tsunami could reach 6 feet when it hits parts of the northern California coast.
"They are starting to roll in," said Jordan Scott, spokesman for the California Emergency Management Agency.
He said some people were being evacuated from their homes in Del Norte and San Mateo counties. Del Norte is the northernmost California coastal county. San Mateo includes much of Silicon Valley, but the technology center is well inland.
Authorities in the neighboring state of Oregon advised coastal residents to evacuate and schools were to be closed along the coast.
SIRENS BLARE IN HAWAII
In Hawaii, some 3,800 miles 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 officials ordered the evacuation of all Hawaiian coastal areas, including the tourist hub of Waikiki Beach on Oahu island, by 2 a.m. local time, about 90 minutes before the first wave hit.
Civil defense sirens blared statewide, starting shortly before 10 p.m. local time, and police with bullhorns urged residents near shore to higher ground. Lines for gasoline stretched for blocks, and people rushed to stores to stock up on food and water.
President Barack Obama, a native of Hawaii, was notified of the massive Japanese quake at 4 a.m./0900 GMT and instructed FEMA to be prepared to help affected U.S. states and territories, the White House said.
CHILE RESIDENTS ALERT
On Easter Island, a Chilean territory in the South Pacific, authorities planned to move residents to higher ground, in preparation for a possible tsunami on Friday afternoon.
Chilean President Sebastian Pinera, whose country was hit by a devastating 8.8 magnitude quake and ensuing tsunamis that killed more than 500 people a year ago, called on Chileans to remain alert, but to continue with their daily routines.
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.
Any tsunami waves were forecast to first hit Peru in the northern city of Tumbes, near the border with Ecuador, around 5:30 pm local time (2230 GMT), and arrive in Lima two hours later. Any evacuations would be ordered about two hours before the arrival of the waves, officials said.
In the northwestern Mexican city of Mazatlan, shops were shutting down and the coastal road was closed before the expected arrival of waves up to 9 feet high around 1900 GMT. Some communities were being evacuated.