Tsunami threat recedes from 7.7 earthquake near Nicobar islands

India's tsunami centre warned that the major quake near the Nicobar Islands would generate a 50-cm surge in sea levels on the nearest islands, adding this was "nothing alarming."

"We have sounded a 'tsunami watch' for 10 to 15 island locations where expected water level could be around 0.5 metres in the next 30 to 60 minutes," Sriniwas Kumar, a spokesman from the Indian National Centre for Ocean Information Services, said.

"This is nothing alarming but just a watch," he said from the headquarters of the agency in Hyderabad.

Residents from Chennai and Nellore felt tremors from the quake. There were no immediate reports of damage.

Residents in Chennai and Nellore said they felt the strong tremors at about 1.30 am on Sunday.

People in panic rushed out of their houses at Gopalapuram, Kodambakkam, Porur, Thiruvanmiyur, Anna Nagar and several other places under the impact of the tremor which lasted for a few seconds, reports said from Chennai.

The earthquake struck the Indian Ocean near India's Nicobar Islands at 1.26 am local time, the US Geological Survey said.

The quake was recorded at a depth of 35 km with the epicentre around 160 km west of the Nicobar Islands.

Earlier, the Pacific Tsunami Warning Centre downgraded a tsunami watch for the Indian Ocean after the quake.

The centre had earlier issued a tsunami watch for all areas of the Indian Ocean following the quake.

The warning said earthquakes of this size had the potential to cause destructive local and sometimes regional tsunamis, but added it was not yet known that a tsunami had been generated.