HONOLULU -- Tsunami advisories for Hawaii and California were dropped Thursday following a powerful earthquake off Chile, while minor effects were recorded along coasts as far north as Alaska.
The Pacific Tsunami Warning Center first issued a more serious tsunami watch for Hawaii shortly after Wednesday's magnitude-8.3 earthquake. Officials later downgraded that to an advisory, saying no major tsunami was expected in the state.
But they warned that sea-level changes and dangerous currents could pose a threat to those in or near the water.
A 3-foot wave was recorded at Hilo Harbor on Hawaii's Big Island shortly after 4 a.m. Thursday, National Weather Service forecaster Tom Birchard said from his Honolulu office. He said he hadn't heard of any significant impacts.
Tsunami wave heights across Hawaii were below advisory levels and continued to diminish, the Pacific Tsunami Warning Center said in cancelling the advisory.
"Small sea level changes and strong or unusual currents may persist for several additional hours in some coastal areas and appropriate caution should exercised by boaters and swimmers," the centre said.
Tsunami effects also were felt along the coasts of California, Oregon, British Columbia and Alaska. King Cove, Alaska, reported water heights of 0.6 foot late Tuesday morning, the tsunami warning centre said.
In California, a slight ocean surge and powerful currents were reported at points along the entire coast, scientists and local officials said.
Swimmers and surfers were warned of strong currents and urged to stay out of the water.
Ventura Harbor in Southern California experienced a 1.1-foot tsunami, while 0.4 foot heights were reported in San Diego to the south, and 0.8 foot heights were seen at Crescent City near the Oregon border, according to the National Tsunami Warning Center. Los Angeles-area beaches and harbour saw water level heights around a half-foot.
Boats were bobbing in Ventura Harbor, said harbourmaster John Higgins.
"You'll see slow-moving streams coming in and going out, and at times the two converge upon each other and it creates turbulent water movement," he said.
The activity was "completely manageable" and not expected to have damaging effects, Higgins said.
The surge was expected to continue for several hours, with wave cycles every 20 minutes and heights topping out at around one foot, said Paul Whitmore, the tsunami centre's director in Palmer, Alaska.
"It doesn't sound like much, but even a very small tsunami has a lot of power," he said.
Orange County beaches, harbours, piers and marinas were reopened at 6 a.m., but swimmers and boaters were warned that strong currents could continue.
A tsunami advisory was issued Wednesday evening for a 300-mile stretch of California, from south Orange County to Ragged Point about 50 miles northwest of San Luis Obispo. It was finally cancelled early Thursday afternoon.
A tsunami warning was last issued for Hawaii in 2012, after a powerful earthquake off the coast of Canada. The Pacific Tsunami Warning Center lifted its tsunami advisory three hours after downgrading from a warning and less than six hours after the waves first hit the islands. The state was spared from severe surges.
- Associated Press writers Audrey McAvoy in Honolulu, Andrew Dalton in Los Angeles, Bob Seavey in Phoenix and Mark Thiessen in Anchorage, Alaska, contributed to this report.
