A 7.5-magnitude earthquake struck off the coast of Alaska near midnight on Friday, the U.S. Geological Survey said, prompting tsunami warnings and advisories down the coast of Alaska and Canada's British Columbia.

All tsunami warnings, watches and advisories were later canceled, the West Coast and Alaska Tsunami Warning Center (of the National Oceanic and Atmospheric Administration) said.

The Alaska Tsunami Warning Center said the waves were too small to pose a threat, reaching just six inches above normal sea level in places such as Sitka and Port Alexander.

"Initially, in the first 15 to 20 minutes, there might have been a bit of panic," Sitka Police Chief Sheldon Schmitt told The Associated Press. But he said things calmed down as the town waited for the all clear and the tsunami warning was canceled by 2 a.m., according to the Daily Sitka Sentinel.

Residents of Sitka gathered at the high school early Saturday, bundled up with pillows in tow, waiting for more information.

The quake struck in the Pacific Ocean about 60 miles southwest of Port Alexander, Alaska, at a depth of about 6 miles at 11:58 p.m. local time (3:58 a.m. ET), the USGS said.

Initially, the USGS reported that the temblor had a magnitude of 7.7, but it later downgraded the quake's strength to 7.5.

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A 6-inch rise in sea level was reported in Port Alexander, but there were no early reports of damage.

A tsunami warning was issued for the coastal areas of British Columbia from the north tip of Vancouver Island to Cape Suckling, but it was later canceled.

"A tsunami was generated by this event but does not pose a threat to these areas," NOAA said in a statement. "Some areas may see small sea level changes. The decision to re-occupy hazard zones must be made by local authorities."

The NOAA also issued tsunami advisories from the Washington state-British Columbia border to the north tip of Vancouver Island. They were later canceled.

According to the NOAA, a tsunami warning means "that a tsunami with significant widespread inundation is expected or is already occurring."

There was no danger of a tsunami hitting Hawaii, according to the NOAA's Pacific Tsunami Warning Center.

The Associated Press contributed reporting.

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USGS

An earthquake map from the USGS shows Saturday's 4.3-magnitude quake.

Updated at 5:40 p.m. ET: A 4.3-magnitude earthquake struck eight miles west of Whitesburg, Ky., early Saturday afternoon, the U.S. Geological Survey reported.

The epicenter of the shallow, light earthquake was 0.7 miles deep under the Appalachian Mountains town of Blackey, near the Virginia border, the agency said.

There were no immediate reports of damage in the eastern Kentucky area.

The tremor was felt from Cincinnati, Ohio, to Atlanta, Ga., USGS geophysicist Paul Caruso in Denver told NBC News.

"Normally, we don't expect major damage with this kind of intensity," but it's "not out of the question" that there could be some -- usually, major damage is expected when magnitude is 5.5 or higher, Caruso said.

Whitesburg police and fire officials told NBC News late Saturday afternoon that after making round they had no visible damage, only people calling to report that they "felt jolts."

Earlier, the Letcher County Sheriff's office said it was still assessing the quake but had no reports of damage or deaths. 

Nick Howell, at Parkway Inn Hotel in Whitesburg told NBC News he felt light jolts but nothing serious. There was no visible damage outside, he said. 

Most Kentucky temblors historically have occurred in the western portion of the state, near the New Madrid seismic zone, the USGS says.

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This story includes reporting by NBC's Michelle Acevedo, Ali Fateh, Brittany Tom and Jim Gold.

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USGS

USGS Intensity Map of New Jersey shaking

South New Jersey residents felt the ground shaking Saturday morning, but no earthquakes or military training exercises were reported in the region.

The U.S. Geological Survey suggested a possible sonic boom was the cause.

"I'm in LEH [Little Egg Harbor] and my basement door shook violently for 15 sec or so long enough to creep me out. Sounded like someone was trying to get out," posted a person identified as Dana Re on the Jersey Shore Hurricane News Facebook page.

Another comment, posted by a person identified as John Tefankjian, said he felt his Brigantine house shake, but differently from when fighter jets go by in training.

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"There currently is no training of any type that would have resulted in today's incident," Joint Base McGuire-Dix-Lakehurst spokesman Pascual Flores told NBC News on Saturday.

The New Jersey National Guard last weekend conducted artillery-fire training that it told the public about in advance.

NBCPhiladelphia.com reported that residents in Atlantic, Cape May, Ocean, Salem and Camden County claimed they felt the ground shake.

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Comments on the shaking were also posted on independent Earthquake-Report.com.

"Felt like a rumble, everyone ran outside, we all noticed on our street," said one from Ocean City.

"Whole house started shaking, outside sounded like a bomb with slight shaking," said one from Little Egg Harbor.

NBC News' Jim Gold and NBCPhiladelphia's Lauren DiSanto contributed to this story.

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Updated at 9:28 p.m. ET: A 4.0-magnitude earthquake struck west of Portland, Maine, on Tuesday evening, the U.S. Geological Survey said, and the tremor reportedly was felt around New England.

The USGS said the quake struck at 7:12 p.m. ET and was centered about three miles west of Hollis Center, Maine. That's about 20 miles west of Portland. It was a shallow quake at 3.1 miles deep.

The USGS "Did You Feel It?" map showed reports throughout New England from Maine to southwestern Connecticut and east to New York state.

"I was watching TV and I felt it and looked at a vase on the table and the flowers were moving," said Roger Nascimento, of West Hartford, in a Facebook comment to NBCConnecticut.com.

The USGS initially gave the earthquake a 4.6-magnitude rating and later downgraded it to 4.0.

The shaking was felt down to the Connecticut shoreline.

"Felt it here in the Fair Haven section of New Haven," said Carl Forlano, Jr. on Facebook. "Was sitting at the computer and the computer desk shook and the chair. Right away I knew it was an earthquake."

There were reports of minor damage near the epicenter, such as food falling off store shelves, according to WCSH-TV in Portland, Maine. Some cell phone service outages were also being reported. 

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ANCHORAGE, Alaska - A powerful earthquake rocked one of the few inhabited islands in Alaska's Aleutian chain on Wednesday, but no damage has been found, federal and local officials said.

The magnitude 6.9 quake, centered 80 miles southwest of Adak, struck at 3:40 p.m. local time (7.40 p.m. ET), the West Coast and Alaska Tsunami Warning Center said. No tsunami warning was issued, but scientists will monitor the area for any possible earthquake-related waves, center Director Paul Whitmore said.

In Adak, a community of about 330, "We definitely felt it," City Manager Layton Lockett said.

The building that houses city offices and the local school, engineered to withstand frequent earthquakes that strike the region, performed as designed, Lockett said.

"You could just hear the building move, and things were shaking," he said.

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No damage was found, though officials were concerned about the fate of underground pipes, he said. The school, which has about 20 students, was out of session at the time.

Adak, an island city about 1,300 miles southwest of Anchorage, is a converted U.S. Navy station that once housed 6,000 people. It now operates as a port and seafood-processing center serving the North Pacific commercial fishing fleet.

Other moderate earthquakes have struck western Alaska in recent days, according to the center.

A magnitude 4.9 quake was recorded 90 miles west of the Alaska Peninsula town of Cold Bay on Tuesday. A magnitude 5.2 quake about 90 miles southwest of Kodiak was recorded on Sept. 18.

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A map shows the location of one of the quakes that struck near Huron, Calif., on Friday.

Two earthquakes struck in Huron, Calif., Friday, registering magnitudes of 4.2 and 4.0, according to the U.S. Geological Survey.

The first earthquake hit at 6:22 a.m. PT. One minute later, the 4.2 earthquake was reported.

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According to the USGS, the epicenter was eight miles from Avenal, Calif., nine miles from Kettleman City, Calif., 17 miles from Coalinga, Calif., and 132 miles from San Jose. Huron, Calif., is about 50 miles south of Fresno. 

About six hours earlier, a magnitude 3.5 earthquake struck Beverly Hills. Thousands of people reported feeling it, the Associated Press reported.

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A spokesman from the USGS told NBC News the earthquakes caused no reported damage.

Seismologists say the quakes are not on the San Andreas Fault and weren’t triggered by a magnitude-7.6 earthquake in Costa Rica, according to the Associated Press.

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