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By Michael Byrnes

SYDNEY, March 25 (Reuters) - Two strong earthquakes struck on Sunday near the archipelago of Vanuatu in the South Pacific, Australia's geological agency reported, but there were no reports of damage.

The first quake, measured at magnitude 7.3 at 0040 GMT, occurred two minutes before a large quake jolted the western coast area of central Japan.

Vanuatu's second quake, at magnitude 7.1, occurred 28 minutes later.

Police on Vanuatu, an islands nation of 209,000 people which is popular with divers, said there appeared to be no damage, although buildings in the capital, Port Vila, shook when the quakes occurred.

"So far we haven't received any damage or any injury," Senior Inspector Tapeirangi Seru told Reuters by telephone from Port Vila. "There's a shaking of buildings, but not strong enough to damage the buildings here."

Vanuatu, which is around 2,000 km (1,240 miles) east of Australia, around three-quarters of the way from Hawaii to Australia, is regularly rattled by earthquakes.

It is perched on the so-called Pacific ring of fire, a zone of frequent earthquakes and volcanic eruptions.

Its clear waters, coral reefs, volcanoes and pristine forests are a big draw for tourists.

There was a state of emergency in Port Vila for two weeks this month after tribal clashes left three people dead.

However, Vanuatu has escaped the worst of the rioting, gang warfare and military coups which have shattered the peace in other South Pacific island nations in recent years.

Australia's geological agency Geoscience Australia said on Sunday that Vanuatu would likely escape quake damage.

"I wouldn't be expecting any damage," said Mark Leonard, the duty seismologist at Geoscience Australia. "Earthquakes of this size only do damage 50 or 100 km (30 or 60 miles) away and there was no land (nearby), unlike the Japan one," he said.

The earthquake occurred out at sea, within 200-300 km (125-190 miles) of Vanuatu's southern islands, he said.

No tsunami warning had been issued for Vanuatu and no damage had been reported, he said.

"It's likely that it's caused a very small tsunami ... about 0.3 or 0.4 of a metre (12 or 16 inches) in that local area," he said.

The U.S. Geological Survey said the first Vanuatu quake was centred 337 km (210 miles) south-south-east of Port Vila and 1,833 km (1,140 miles) east-north-east of the Australian city of Brisbane.

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