Hawaii, October 28,2012: Gerard Fryer, a geologist tracking the tsunami for the Pacific Tsunami Warning Center, said the largest wave in the first 45 minutes of the tsunami was measured at 5 feet (1.5 meters) in Maui.
State and local officials warned residents and tourists not to go back to inundation zones until an all-clear is given.
At first, officials said Hawaii wasn't in any danger of a tsunami after the 7.7-magnitude earthquake rattled the western coast of North America on Saturday night, sparking tsunami warnings for southern Alaska and western Canada.
Later, officials issued a warning for Hawaii as well, saying there had been a change in sea readings. About the same time, a tsunami advisory was issued for a 450-mile (724-kilometer) stretch of U.S. coast running from north of San Francisco to central Oregon.
A small tsunami created by the quake was barely noticeable in Craig, Alaska, where the first wave or surge was recorded Saturday night.
Fryer said that could take several hours for the danger to pass in Hawaii, especially if the waves get bigger.
“It's beginning to look like the evacuation may not have been necessary,” Fryer said.
The National Weather Service said there were reports of water quickly receding in bays, including Hilo Bay on the Big Island.
The warning in Hawaii spurred residents to stock up on essentials at gas stations and grocery stores and sent tourists in beachside hotels to higher floors in their buildings.
Bus service into Waikiki was cut off an hour before the first waves, and police in downtown Honolulu shut down a Halloween block party.
Gov. Neil Abercrombie proclaimed an emergency, mobilizing extra safety measures.
While television traffic cameras showed onlookers at the beach in Waikiki, Honolulu Mayor Peter Carlisle warned people to stay away from the surf for several days.
Carlisle who recommended people think about ditching their cars if they were in traffic said people should be cautious.
“There's no reason to panic but there's every reason to take all of the necessary precautions,” he said.
Coast Guard officials closed all harbours in the state to incoming boats and urged vessels to leave and not return until an all-clear is given.
“We don't have any reports of any tsunami impacts at this time, but we caution mariners because the tsunami surges can continue for several hours,” Chief Warrant Officer Gene Maestas said.
In Kauai, three schools used as evacuation centres quickly filled to capacity.
As many people along Hawaii's coasts rushed to higher ground, officials downgraded a tsunami warning to an advisory for southern Alaska and British Columbia.
They also issued an advisory for areas of northern California and southern Oregon.
In Alaska, the wave or surge was recorded at 4 inches (100 millimeters), much smaller than forecast, said Jeremy Zidek, a spokesman for the Alaska Department of Homeland Security and Emergency Management.
The U.S. Geological Survey said the earthquake hit in the Queen Charlotte Islands area.
The quake was felt in Craig and other southeast Alaska communities, but Zidek said there were no immediate reports of damage.
The West Coast and Alaska Tsunami Warning Centre issued a warning for coastal areas of southeast Alaska, down the western Canadian coast to the tip of Vancouver Island.
Later Saturday evening, the warning for those areas was downgraded to an advisory, while a warning was issued for Hawaii.
Early Sunday, the advisory was cancelled entirely for Alaska.
A tsunami warning means an area is likely to be hit by a wave, while an advisory means there may be strong currents, but that widespread inundation is not expected to occur.
The U.S. Coast Guard in Alaska said it was warning warn everyone with a boat on the water to prepare for a potential tsunami.
Lucy Jones, a USGS seismologist, said the earthquake likely would not generate a large tsunami.
“This isn't that big of an earthquake on tsunami scales,” she said. “The really big tsunamis are usually up in the high 8s and 9s.”
She said the earthquake occurred along a “fairly long” fault—“a plate 200 kilometres long” in a subduction zone, where one plate slips underneath another.
Such quakes lift the sea floor and tend to cause tsunamis, she said.
