(CNN) -- For the fourth time in less than 11 hours, a major earthquake rocked the South Pacific Ocean near the island nation of Vanuatu on Thursday, the U.S. Geological Survey reported.
They were part of a series of 16 moderate-to-major quakes that rattled the region over the same period.
The first three major quakes struck in a 70-minute cluster beginning at 9:03 a.m. (6:03 p.m. ET Wednesday). The fourth temblor hit Thursday evening at 7:29 p.m. (4:28 a.m. ET).
The Pacific Tsunami Warning Center on Hawaii issued and then quickly retracted a regional tsunami warning and watch for parts of the Pacific near the first earthquake's epicenter. The quakes that followed prompted no such warnings.
There were no immediate reports of damage or injuries, said Victor Sardina, a geophysicist with the Pacific Tsunami Warning Center on Hawaii.
At the Hotel Le Paris in Noumea, the capital of New Caledonia, the manager told CNN that she felt the shake, but had not seen any damage.
On Espiritu Santo Island in Vanuatu, dive-shop owner Rehan Syed said he was not aware of reports of damage or injuries.
"We have the sun out and winds are pretty normal," he said. "Pretty cloudy skies, but nothing more than that."
"We felt the quake (my chair and my keyboard moved), but did not take too much notice as we live with shakes every week," John Nicholls of Vanuatu Hotels said in an e-mail.
At the New Caledonia Hotel, General Manager Torani George told CNN he had felt "nothing, nothing at all."
"There is no panic, nothing," he said.
Sardina said the two major quakes that followed the first one were aftershocks.
"When there's a big quake, the pattern they follow is after the first quake, a second and then a third," he said. "Those are obviously related," he said.
Vanuatu is about 1,100 miles (1,750 km) east of northern Australia and some 600 miles (1,000 km) west of Fiji.