SYDNEY, Aug 10, 2010 (AFP) - A major 7.5-magnitude earthquake hit the Pacific island nation of Vanuatu on Tuesday, generating a small tsunami and sending thousands of frightened people running for the hills.

The undersea quake, 35 kilometres (22 miles) deep and just 40 kilometres from the capital Port Vila, shook buildings in the city for about 15 seconds, but did not appear to have caused significant damage.

Foreign hotel guests and some residents raced to higher ground in case of a possible tsunami, locals said, while police sounded sirens to warn people to evacuate.

"We don't have any damage. But we have evacuated our guests to the top of the hill just to be safe, although we have not received any tsunami warning yet," hotel employee Rowan Lulu told AFP.

"A lot of people are evacuating to higher ground in the city as a precaution but as far as I know there is no major damage in Vila, just things falling off shelves," he said.

"We felt it very strongly," another hotel employee said.

Witnesses said people working in the capital's tallest buildings were also evacuated, while the powerful quake was felt in the archipelago's other islands further north.

"People were moving to higher ground," resident Steve Ayong-Nirua told AFP. "There was a call on the radio calling on drivers to drive slowly in case of aftershocks," he added.

The Pacific Tsunami Warning Center said a 23-centimetre (9.2 inch) tsunami hit Port Vila, but warned bigger waves may be seen in other areas.

"Higher wave amplitudes may yet be observed along coasts near the earthquake epicentre," the Center said.

Vanuatu, which lies between Fiji and Australia and north of New Zealand, is in the "Pacific Ring of Fire" known for its high seismic and volcanic activity caused by friction between moving plates in the Earth's crust.

In May, a 7.2 earthquake prompted a brief tsunami alert, and at least three earthquakes measuring 6.0 or stronger have hit the archipelago since the start of July.

The country was hit by three major quakes last October, while a giant plume of volcanic ash disrupted domestic flights in neighbouring New Caledonia in recent months.

The US Geological Survey measured the latest earthquake at 7.5 while Geoscience Australia said it was 7.6 and at a depth of 60 kilometres.

The Pacific centre said it did not cause a widespread tsunami, while scientists in New Zealand believed the country was not under threat from any destructive waves.