The earthquake struck at a depth of only 10km off Aceh, at the northern tip of Sumatra, about 364km from Phuket, at 5.03am.
The earthquake, with an epicentre at latitude 5.22N and longitude of 96.26E, registered an initial reading of 6.5 magnitude.
The Thailand Seismology Department issued a notice signed by Director Wanchai Sukudomchai at 5:15am stating that the ensuing tremors were felt in Phang Nga, Phuket, Krabi and Trang.
No tsunami warning was issued.