Honolulu (CNN) -- As the first light of dawn broke Friday in Hawaii, officials reported no significant damage from a series of tsunami waves that struck the islands after Japan's deadly earthquake.
Tsunami brought waves of nearly 7 feet to a harbor in Maui, authorities said, but other areas reported lower levels.
The West Coast was bracing for waves to come onshore from Washington to California.
No significant damage had been reported in Hawaii almost three hours after the first waves arrived, but officials said they would know more after sunrise.
Kerry Gershaneck of the Pearl Harbor Naval Shipyard told CNN affiliate Hawaii News Now that the operation was open.
Honolulu Mayor Peter Carlisle told the station he was not yet prepared to issue an "all clear".
The Pacific Tsunami Warning Center predicted the waves, which came in about every 15 minutes, "are not going to be a major damaging event" for Hawaii, but will cause scattered damage, particularly to harbors and coastal facilities.
It appeared the state's residents had heeded calls to move away from the coast. Honolulu officials told residents to "be aware that inundation effects could continue for several hours".
"We called this one right," said center geophysicist Gerard Fryer. "This evacuation was necessary".
Waves of between 6 and 7 feet were reported at Kahului harbor in Maui, said Fryer, adding it was difficult to tell what would happen on all the islands. "We have significant energy bouncing around the Hawaiian Islands".
Waves of about 3 feet were reported on Hilo.
Fryer said the waves are rolling in about 15 minutes apart. Forecasters said some areas may see waves of up to 9 feet.
A tsunami warning was still in effect after 7 a.m. (10 a.m. ET).
Communities along much of the U.S. West Coast were under tsunami warnings, too.
The National Weather Service said the waves would hit Oregon and California between 7:15 a.m. and 8 a.m. local time (10:15-11 a.m. ET).
In California, tsunami wave heights could reach 7 feet at Port San Luis Harbor and 4 feet in Morro Bay. Santa Monica could see 2.8 feet.
The first impact in Hawaii was felt shortly after 3:07 a.m. (8:07 a.m. ET), according to Hawaii State Civil Defense, which issued a tsunami warning.
Tidal gauge readings on the southern side of the Hawaiian island of Kauai were "somewhat encouraging," CNN meteorologist Rob Marciano said.
Hawaii Public Radio news director Bill Dorman told CNN some roads were closed as a precaution.
Hawaiian emergency officials reminded residents that tsunami evacuation maps can be found in front of their telephone directories. People were advised not to make unnecessary phone calls and a coastal evacuation was conducted.
Chief Petty Officer Kurt Fredrickson in Honolulu told CNN the U.S. Coast Guard has been working with local port authorities and harbor masters to get the word to all mariners to get out to sea.
The Coast Guard prepared for the worst-case scenario, Frederickson said. "We are moving our assets out to sea. We are moving our aircraft to more suitable locations".
The threat of a tsunami prompted the U.S. National Weather Service to issue a warning for at least 50 countries or territories around the Pacific after the 8.9-magnitude earthquake struck Japan Friday. The warning for Guam was later lifted.
Warnings also were in effect for coastal areas of California and Oregon from Point Concepcion, California, to the Oregon-Washington border, according to the U.S. Pacific Tsunami Warning Center.
A warning also was in effect also for Alaska, from Amchitka Pass to Attu, and in Canada's British Columbia.
President Barack Obama said he instructed the Federal Emergency Management Agency to be prepared to help Hawaii and other U.S. regions "that could be affected" by the disaster.
He also said the United States "stands ready to help the Japanese people" slammed by a destructive tsunami.
CNN iReporter Ken Papagno, who lives on the Hawaiian island of Oahu, recorded sirens that sounded throughout the island.
Hawaii had a tsunami scare in February 2010 after an 8.9-magniture earthquake hit Chile. A warning cancellation occurred nearly two hours after the first waves came ashore. Coast Guard crews said they had found no significant damage to ports or waterways as a result of the tsunami, ending a significant evacuation to higher ground. CNN
