Hawaii scientists and emergency personnel kept watch on a tsunami generated by a magnitude-8.2 earthquake off Chile on Tuesday, the anniversary of the 1946 tsunami that devastated Hilo.

Pacific Tsunami Warning Center officials noted that Tuesday’s Chilean earthquake occurred on the same day that a magnitude-8.1 earthquake in the Aleutian Islands that killed 159 people in Hawaii, most of them in Hilo, in 1946. To commemorate that event, April 1 is the start of Tsunami Awareness Month in Hawaii.

As Tuesday wore on, officials determined that the tsunami would be small and provide strong currents around Hawaii’s shorelines.

Residents of the Hawaiian Islands were told to stay out of the ocean until about 8 a.m. or possibly later Wednesday as a precaution against hazardous currents and tidal surges, the only expected impacts from the Chilean earthquake.

Tuesday’s earthquake struck about 59 miles northwest of Iqui­que, Chile, at a depth of about 12.5 miles at 8:46 p.m. (1:46 p.m. Hawaii time). At least five people were reported dead in the quake as well as related aftershocks, a tsunami and landslides.

"Based on all available data a major tsunami is not expected to strike the state of Hawaii," the National Weather Service’s warning center said in issuing an advisory.

"However, sea level changes and strong currents may occur along all coasts that could be a hazard to swimmers and boaters as well as to persons near the shore at beaches and in harbors and marinas," the advisory said.

Charles "Chip" McCreery, PTWC’s geophysicist in charge, said a tsunami advisory means "there is a threat for swimmers — strong currents, maybe minor flooding of beaches, harbors, but no real flooding of the land that would require a full evacuation."

"Everyone should be cautious around the ocean," he added.

Geophysicist Gerard Fryer said wave action will be modest, perhaps an increase of 1 or 2 feet. "What we’re really worried about is currents," he said. "And occasionally … you get a larger wave … and if you’re not ready for it, it could be difficult. … You could get banged about. So we really want to keep people out of the water, the closer it comes."

The first waves were expected at about 3:20 a.m. Wednesday.

The U.S. Coast Guard also advised the public to remain vigilant of hazardous currents and tidal surges Wednesday morning.

All mariners should "ensure that their vessels are secured for possible changes in sea conditions and that all individuals use caution when taking part in water activities," Coast Guard officials said.

Honolulu Mayor Kirk Caldwell said the city is exercising "an abundance of caution" by closing beaches through most of the morning.

"We’re going to have weird kind of tides and fluctuations in waves. They can reverberate for hours," Caldwell said Tuesday evening.

The partial activation at Oahu Civil Defense calls for officials from Hono­lulu police, the Fire Department as well as ocean safety and emergency medical service officials to be called in to talk about how to protect the public, Caldwell said.

City personnel will ensure people don’t go into the water from 3 until 8 a.m., or possibly 10 a.m. or later, the mayor said. Hanauma Bay is expected to be closed the entire day.

Caldwell said Oahu could see some minor flooding at the beaches and beach parks, and community service workers are going to alert people, including the homeless, in the Wai­anae-Nana­kuli coastline to be careful.

Tsunami waves are expected to hit Hilo Bay at 3:25 a.m., Maka­puu on Oahu at 3:50 a.m., Hono­lulu by 3:55 a.m. and Hale­iwa by 3:56 a.m.

"That’s when we’ll be feeling the brunt of the impact," Caldwell said.

At least 10 aftershocks greater than magnitude 5 were recorded in the hours after the quake.

Fryer said there is a small chance that the 8.2 earthquake was a "forequake" of a larger event to come, insisting it was highly unlikely.

"We think this is the main event," Fryer said.

For several hours after the quake, PTWC officials at Ewa Beach said it did not have enough information to determine whether Hawaii should go under a tsunami watch or warning.

At about 5 p.m. the center said it had gathered and analyzed enough data to ensure there was no danger to inland portions and that it issued an advisory.

A 1960 earthquake off the coast of Chile caused a tsunami that led to the death of 59 people in Hilo and elsewhere in Hawaii, and caused widespread destruction.

In October 2012 Hawaii was put into a tsunami warning following a magnitude-7.7 earthquake off northern Canada.

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Star-Advertiser reporters Gary Kubota and Tim Hurley contributed to this report.