The Pacific Tsunami Warning Center lifted a tsunami advisory for Hawaii at 3:58 a.m., as tsunami wave and surge activity continued to diminish after Saturday night’s 7.7 magnitude earthquake in Canada.

The center said sea level changes and unusual currents may persist and swimmers should be cautious.

After the advisory was lifted, the Coast Guard began reopening harbors. Beaches also began reopening, although Hanauma Bay remained closed.

A popular triathlon set for Maui today was expected to go on as planned, with county lifeguards giving the OK for a 1 mile ocean swim.

There were no immediate reports of damage in the state, though one person died in a fatal crash near a road that was closed because of the threat near Oahu’s north shore.

“We’re very, very grateful that we can go home tonight counting our blessings,” Gov. Neil Abercrombie said after the warning was downgraded at about 1 a.m.

The  Pacific Tsunami Warning Center downgraded the tsunami warning to an advisory just before 1 a.m., today, allowing the thousands of people who evacuated inundation zones for several hours to return to their homes and hotel rooms.

Mayors in different counties reduced the warning status, and police reopened roads to coastal areas.

The warning and advisory were downgraded after experts observed the size of the waves from 13 gauges around the Hawaiian islands consistently dropping. 

Charles McCreery, director of the Pacific Tsunami Warning Center, said wave energy gets trapped around the islands and resonates for hours. 

“It may look like it’s going down for awhile and can pop back up again. So we kind of have to wait a reasonable amount of time to make sure that the threat really is diminishing and isn’t going to pop back up,” he said.

Geophysicist Gerard Fryer said the biggest waves generated from a tsunami usually occur in the first half dozen of waves. “From then on, they tend to get smaller,” he said.

Tsunami warning center officials plan to assess Saturday’s event sometime this week as standard procedure. Geophysicist Victor Sardina said the warning was issued largely because models showed wave energy was heading directly toward Hawaii. It was unusual, he said. 

Waves, about 12 minutes in duration, began arriving in Hawaii at about 10:30 p.m.

The highest wave recorded measured about 2.5 feet above sea level in Kahului Harbor.

Gauges initially recorded a 1.6 foot wave at Makapuu at about 10:30 p.m. Kahului Harbor  recorded a similar sized wave about 20 minutes later. Smaller waves were recorded in Waianae and Hanalei.

“The tsunami arrived about when we expected it should. It was a little smaller than we expected,” Fryer said.

Hawaii Island Mayor Billy Kenoi said shortly after midnight that Waialoa Small Boat Harbor in Hilo experienced four-foot surges at intervals of every six minutes. Some boats had partially pulled of their moorings, but he said there were no reports of any vessels breaking completely free.

Kenoi said a total of about 830 people were staying at emergency shelters set up by the county at Big Island schools and parks.

Maui,County spokesman Rod Antone said as of 11 p.m. there were no reports of water damage at Kahului Harbor, unlike after the Japan quake where water went inland for several hundreds yards. He reported there were evacuations at the Maui Beach Hotel and Maui Seaside Hotel .

Maui saw none of the traffic problems experienced on Oahu. 

Fryer said the initial waves were about 12 minutes in duration and about four waves had hit by 11:15 p.m.

The tsunami waves that hit Hawaii from last year’s Japan earthquake were about 20 minutes long, so they were much more powerful, Fryer said.

A typical wave ridden by a surfer is about 20 seconds in duration.

The tsunami warning was issued for Hawaii 7:14 p.m., more than two hours after a 7.7-magnitude earthquake off British Columbia. Immediately after the earthquake, the warning center had said Hawaii was not under a tsunami threat from the quake, but may see strong or unusual currents and sea-level changes.

Center officials later revised their assessment after receiving more data and issued the warning that set Hawaii scrambling. Tsunami warning sirens sounded across the state and most people in inundation zones evacuated.

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 at 10:30 p.m., and police in downtown Honolulu shut down a Halloween block party.

State Civil Defense urged residents to move to higher ground if they were in a tsunami evacuation zone.

The center had predicted wave heights of 3 to 6 feet in some locations. 

McCreery, of the warning center, said the waves would not be as big as the waves that hit Hawaii from the March 2011 Japan earthquake. Still, a tsunami three feet in height is powerful enough to carry a fishing boat and push it inland, he said.

“It may not be very high but it’s very, very broad and contains a huge amount of water,” he said.

Abercrombie issued a statewide emergency proclamation at about 9:45 p.m., giving civil defense officials the authority to protect lives.

“I want to make sure everybody understands how serious this is. We’re getting reports of people trying drive to shore areas, endangering other people trying leave shore areas. I want to make crystal clear to everybody to have all the authorities on all of the islands to take appropriate actions to control whatever needs to be done for civil defense purposes,” Abercrombie said.

John Cummings, a spokesman for Oahu Civil Defense, said there were reports of “really bad” traffic in some areas, apparently as residents evacuated from shorelines. He said it appeared people who need not evacuate were also getting on roadways.

Hawaii County opened more than a dozen evacuation shelters. The busiest shelter was the West Hawaii Civic Center in Kona, which housed about 350 people. Another 70 people took shelter at Andrews Gym in Hilo, with other shelters across the island reporting they were accommodating 20 to 50 people.

Tsunami sirens in East Hawaii including the Keauakaha, Waiakea and at least portions of Puna initially failed to work in a “glitch,” but were able to fix the problem, Mayor Billy Kenoi said. The sirens were sounded successfully in the East Hawaii area at about 9:10 p.m.

“We received feed back that throughout East Hawaii from Laupahoehoe and through Keaukaha down to Paradise Park, they’re all working,” Kenoi said. He said the sirens are tested every month.

The Coast Guard led larger boats out of small boat harbors around the state to prevent major damage, said Shelly Kunishige, of Hawaii Civil Defense. Civil Air Patrol aircraft are also flew over shorelines sounding sirens to supplement outdoor sirens, Kunishige said.     

A tsunami is a series of long ocean waves that can flood coastal areas. The danger can continue for many hours after the initial wave arrives, the center said.

The quake in the Queen Charlotte Islands region occurred at 5:04 p.m. Hawaii time, the U.S. Geological Survey reported. The epicenter was 126 miles south-southwest of Prince Rupert, B.C., and 452 miles northwest of Vancouver.The quake in the Queen Charlotte Islands region occurred at 5:04 p.m. Hawaii time, the U.S. Geological Survey reported. The epicenter was 126 miles south-southwest of Prince Rupert, B.C., and 452 miles northwest of Vancouver.

A small tsunami was recorded on a deep-ocean pressure sensor, according to the West Coast/Alaska Tsunami Warning Center in Palmer, Alaska. 

The quake could be among the largest ever recorded in the Pacific Northwest, said John Vidale, director of the Pacific Northwest Seismological Network at the University of Washington. It was followed by a magnitude-5.8 aftershock, and may also be linked to a smaller quake in Montana, he said.

More aftershocks could follow.

Vidale said the quake was not on the Cascadia Subduction Zone, the giant offshore fault that scientists say will one day unleash a megaquake and tsunami similar to the double-punch that hit Japan in 2011.

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The Associated Press contributed to this report.

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