The epicentre of the quake, which had a magnitude of 8.2, was located at about 200km (125 miles) off the mainland.
The US Pacific Tsunami Warning Center said it could cause a 'widely destructive tsunami' and it was felt as far away as Malaysia.
Experts believe it was an after-shock of the quake that struck the Indian Ocean region on 26 December, causing a tsunami that killed tens of thousands of people."
I just heard on NPR that the latest estimate of the magnitude is 8.7 compared with 9.0 for the quake on December 26th that spawned the tsunami.
People in the area affected by today's earthquake write about their experiences here.