Tsunami waves swamped Hawaii beaches and brushed the U.S. western coast Friday but didn't immediately cause major damage after devastating Japan and sparking evacuations throughout the Pacific.
Water rushed up on roadways and into hotel lobbies on the Big Island and low-lying areas in Maui were flooded as 7-foot waves crashed ashore. Smaller waves hit the U.S. western coast and beaches were closed as fishermen fired up their boats and left harbors to ride out the swell.
Scientists warned that the first tsunami waves are not always the strongest, and officials said people in Hawaii and along the West Coast should watch for strong currents and heed calls for evacuations. The tsunami warning was downgraded to an advisory in Hawaii, and Gov. Neil Abercrombie said the islands were "fortunate almost beyond words."
"All of us had that feeling that Hawaii was just the most blessed place on the face of the Earth today," he said.
Maui Mayor Alan Arakawa said Hawaii's second largest island saw the biggest waves. The waves struck as far inland as 100 yards, covering the main roadway, he said.
"The waves were not really that big, fortunately, but enough to cause a little bit of a mess," he said in an interview with FoxNews.com.
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The tsunami, spawned by an 8.9-magnitude earthquake in Japan, slammed the eastern coast of Japan, sweeping away boats, cars, homes and people as widespread fires burned out of control. It raced across the Pacific at 500 mph -- as fast as a jetliner -- before hitting Hawaii and the West Coast.
Sirens sounded for hours before dawn up and roadways and beaches were mostly empty as the tsunami struck. By midmorning, waves were crashing against the 30-foot bluffs in Crescent City, Calif., where a tsunami killed 11 people in 1964.
Dozens of boats were damaged as surging water knocked them from their docks, both in Crescent City and on California's central coast in Santa Cruz, where loose fishing boats crashed into one another and chunks of wooden docks broke off.
President Obama said the Federal Emergency Management Agency is ready to come to the aid of any U.S. states or territories who need help. Coast Guard cutter and aircraft crews were positioning themselves to be ready to conduct response and survey missions as soon as conditions allow.
It is the second time in a little over a year that Hawaii and the U.S. West coast faced the threat of a massive tsunami. A magnitude-8.8 earthquake in Chile spawned warnings on Feb. 27, 2010, but the waves were much smaller than predicted and did little damage.
Scientists then acknowledged they overstated the threat but defended their actions, saying they took the proper steps and learned the lessons of the 2004 Indonesian tsunami that killed thousands of people who didn't get enough warning.
This time around, the warning went out within 10 minutes of the earthquake in Japan, said Gerard Fryer, a geophysicist for the Pacific Tsunami Warning Center in Honolulu.
"We called this right. This evacuation was necessary," Fryer said. "There's absolutely no question, this was the right thing to do," he said.
The warnings issued by the tsunami center covered an area stretching the entire western coast of the United States and Canada from the Mexican border to Chignik Bay in Alaska.
Many islands in the Pacific evacuated, but officials later told residents to go home because the waves weren't as bad as expected.
In Guam, the waves broke two U.S. Navy submarines from their moorings, but tug boats corralled the subs and brought them back to their pier. No damage was reported to Navy ships in Hawaii.
In the Canadian pacific coast province of British Columbia, authorities evacuated marinas, beaches and other areas.
Officials in two coastal Washington counties used an automated phone alert system, phoning residents on the coast and in low-lying areas and asking them to move to higher ground.
"We certainly don't want to cry wolf," said Sheriff Scott Johnson of Washington's Pacific County. "We just have to hope we're doing the right thing based on our information. We don't want to be wrong and have people hurt or killed.
In Oregon, at least one hotel was evacuated in the northern part of the state. Restaurants, gift shops and other beachfront business stayed shuttered, and schools up and down the coast were closed.
Albert Wood of Seaside, Ore., said he and his wife decided to leave their home late Thursday night after watching news about the Japan quake. They stood with dozens of other people on a hilly area overlooking the tourist town to wait out the waves.
Surfers in California who raced to the beach to catch the waves were undeterred by the surges.
"The tides are right, the swell is good, the weather is good, the tsunami is there. We're going out," said William Hill, an off-duty California trooper.
Latin American governments ordered islanders and coastal residents to head for higher ground. First affected would be Chile's Easter Island, in the remote South Pacific, about 2,175 miles west of the capital of Santiago, where people planned to evacuate the only town. Ecuador's President Rafael Correa declared a state of emergency and ordered people on the Galapagos Islands and the coast of the mainland to seek higher ground.
The Honolulu International Airport remained open but seven or eight jets bound for Hawaii turned around, including some originating from Japan, the state Department of Transportation said. All harbors were closed and vessels were ordered to leave the harbor.
About 70 percent of Hawaii's 1.4 million population resides in Honolulu, and as many as 100,000 tourists are in the city on any given day.
A small 4.5-magnitude earthquake struck the Big Island just before 5 a.m. EST, but there were no reports of damages and the quake likely wasn't related to the much larger one in Japan, the USGS said.
The worst big wave to strike the U.S. was a 1946 tsunami caused by a magnitude of 8.1 earthquake near Unimak Islands, Alaska, that killed 165 people, mostly in Hawaii. In 1960, a magnitude 9.5 earthquake in southern Chile caused a tsunami that killed at least 1,716 people, including 61 people in Hilo. It also destroyed most of that city's downtown. On the U.S. mainland, a 1964 tsunami from a 9.2 magnitude earthquake in Prince William Sound, Alaska, struck Washington State, Oregon and California. It killed 128 people, including 11 in Crescent City, Calif.
FoxNews.com's Jana Winter and the Associated Press contributed to this report