(Changes dateline, updates with damage estimates, quotes)
CANBERRA, Aug 2 (Reuters) - A powerful magnitude 7.3 earthquake rattled the Pacific nation of Vanuatu on Thursday, cracking roads and disrupting power supplies, but did not cause major damage, local authorities said.
The quake occurred at 0409 locally on Thursday (1709 GMT Wednesday) about 45 km (30 miles) southeast of the central island of Santo at a depth of around 150 km (90 miles) below the Pacific Ocean surface.
"It's a pretty good size, but it's deep and there is no tsunami threat. It's aways out to sea," Geophysicist Robert Cessaro at the Hawaii-based Pacific Tsunami Warning Center told Reuters.
Jesse Benjamin, a spokesman for the Vanuatu government meteorological office, said the quake was felt strongly on Santo.
"There are cracks in the roads, cracks in the offices, the power went down and computers, but we do not expect major damage," he said from the capital Port Vila.
Shakemap of the earthquake. 
Vanuatu has been hit by a 7.2 magnitude earthquake at 04:14 local time on Friday (17:14 UTC on Thursday). The epicenter was located 215 kilometers to the northwest of , Espíritu Santo, Vanuatu; 340 kilometers to the southeast of , , Solomon Islands; 485 kilometers to the northwest of , Vanuatu; and 2,070 kilometers to the northeast of Brisbane, Australia.

The earthquake had a depth of 36.1 kilometers, approximately 22.4 miles. The Pacific Tsunami Warning Center in  issued a tsunami warning for Vanuatu, Solomon Islands and New Caledonia. They said on the report: "It is not known that a tsunami was generated. This warning is based only on the earthquake evaluation. An earthquake of this size has the potential to generate a destructive tsunami that can strike coastlines in the region near the epicenter within minutes to hours." The Vanuatu government Meteorological Office reported infrastructure cracks, and power outages, but does not foresee major damage. There were no immediate reports of damage or injuries, CNN reported. USGS initially reported the earthquake as 7.6, but they later downgraded it. Magnitude 5.7, 5.2 and 6.4 aftershocks were reported later by USGS.

The tsunami warning was cancelled an hour after it was issued. Geophysicist Barry Hershorn said to The Huffington Post that they had confirmed there was no tsunami from ocean buoys and from coastal sea level gauges in Vanuatu. The Vanuatu goverment said they were pleased the tsunami alert had been canceled. "We haven't received any reports yet about earthquake damage," said Salesa Kaniaha, Meteorological Office acting director of Vanuatu. "The very close proximity of the epicenter to Espíritu Santo the closest island meant there was nothing much we could do to alert residents to any danger," he added.

Vanuatu is an insular country located in southern Pacific Ocean, located 1,750 kilometers to the east of Australia.