There were no reports of injuries from the quake or tsunami, and a Tongan official said a few broken windows were the extent of the damage. The Pacific Tsunami Warning Center in Honolulu lifted its warning for all areas within two hours. It said there was no data indicating that the 4:26 a.m. earthquake generated a giant wave.

The magnitude 7.9 earthquake, classified by the U.S. Geological Survey as "major," struck about 95 miles south of Neiafu, Tonga, and 1,340 miles north-northeast of Auckland, New Zealand. It occurred 20 miles beneath the sea floor.

But nearly 18 months after a tsunami in the Indian Ocean left at least 216,000 people dead or missing, sparking international calls for a better warning system, Pacific islanders got little or no notice of the latest possible tsunami. The failure raised troubling questions about protections in place for inhabitants of the sparsely populated islands scattered thousands of miles across the earthquake-prone region.

The Pacific Tsunami Warning Center said its first alert went out 16 minutes after the earthquake but was not received in Tonga because of a power failure there.

Gerard Fryer, the center's acting director, said "there was problem in Tonga where there was a power outage and they didn't get our initial message."

Fryer said the center needs to work with Tonga to correct the problem. He said he did not know whether the power failure was caused by the earthquake.

Mali'u Takai, deputy director of the Tonga's National Disaster Office, told The Associated Press in a telephone interview that no warning was received.

"Nobody got a warning through the emergency satellite system in our meteorological office," Takai said. "Judging by the location of the epicenter we would have been caught out without any warning at all because of the system's malfunction."

The Honolulu-based center's warning said it was possible a tsunami could strike Fiji within two hours of the quake and then, an hour later, New Zealand.

Speaking about the time a wave was forecast to reach Fiji, police spokesman Mesake Koroi said in the capital, Suva, there had been no immediate reports of a tsunami.

In Gisborne, New Zealand, police Sgt. James Tasmania said civil defense authorities had been put on high alert, but he added that "none of the (ocean) monitoring buoys have reported anything significant."

Hundreds of New Zealanders voluntarily fled for higher ground after seeing TV reports but later returned home, the city's civil defense controller, Richard Steel, told National Radio.

Takai said that Tonga escaped unscathed.

"We have no reports of injury or fatalities or of structural damage throughout the (Tonga Islands) group," Takai said. "There are broken windows in a few houses but that's about it."

Mary Fonua, a publisher in Tonga's capital, Nuku'alofa, said it was the most powerful quake she had felt in 27 years on the island.

"It was rocking and rolling, the floor was shaking, the whole family stood in the doorway and we heard crockery breaking in the kitchen and books fell from the shelves," she said.

"It's very dark and the power went off during the quake ... staff are reporting big flashes as the electricity grid went down during the shake and lines were broken."

"It felt very close but we haven't heard a tsunami warning," she said.

Paula Chipman, a Seattle resident vacationing in Tonga, told CNN she felt the quake at her hotel. She said it "was a shaker, I mean it went up and down and back and forth and it was very, very hard."

When asked what kind of emergency response she saw, she replied: "Nothing. Zero." She also said she heard no warning of a possible tsunami.

Shelves were seen overturned in bookstores. Power in the city was restored after two hours, but most phone lines were jammed by incoming calls.

A police officer in Neiafu, 180 miles north of the Tongan capital, said the quake was felt for about 90 seconds.

"It was strong but not long," duty constable Salesi Baongo said.

Asked whether the tsunami warning had been received, Baongo said, "No, we haven't heard about it."

The center in Hawaii issued a warning that also covered Niue, Samoa, Wallis-Futuna and the U.S. territory of American Samoa.

A tsunami advisory was issued for Hawaii, but the warning center said the earthquake, based on historical records, was not sufficient to generate a tsunami damaging to the Pacific coasts of the United States and Canada, and Alaska. Some areas could experience small changes in sea level, it said.

In Hawaii, schools near shorelines were closed as a precaution.

The warning center's instruments detected a tsunami of less than 2 feet in areas close to the earthquake, geophysicist Barry Hirshorn said.

"We're not observing much of a tsunami," he said. "Strictly speaking, it's not very devastating."

Tonga — a 170-island archipelago about halfway between Australia and Tahiti — has a population of about 108,000 and an economy dependent on pumpkin and vanilla exports, fishing, foreign aid and remittances from Tongans abroad.

Now the last monarchy in the Pacific, Tonga has been a Polynesian kingdom and a protectorate of Britain, from which it acquired independence in 1970. It is ruled by 87-year-old King Taufa'ahau Tupou IV.

On Dec. 26, 2004, the most powerful earthquake in four decades — magnitude 9.0 — ripped apart the Indian Ocean floor off Indonesia's Sumatra island, displacing millions of tons of water and spawning giant waves that sped off in all directions.