The US Geological Survey is reporting a huge 7.6 earthquake in the Indian Ocean about 160 miles north of Port Blair in India's Andaman Islands.
The quake is reported to be 20.6 miles deep.
The Pacific Tsunami Warning Center said on Monday that a regional tsunami watch is in place for India, Myanmar, Indonesia, Thailand and Bangladesh.
The centre says the quake has the potential to generate destructive tsunamis in the region, though it cautions that it is not known if such a tsunami has occurred.
The centre says its bulletin is only issued as advice to government agencies, which must make their own decisions about what action to take.
But it warns that earthquakes of this size have the potential to generate destructive tsunamis along coasts usually no more than a thousand kilometres from the earthquake epicentre.
The earthquake was reported to have struck about 225 miles south-southwest of Myanmar, 510 miles west of Bangkok, and 1,420 miles southeast of New Delhi.
