A major quake and two aftershocks struck off the southern Philippines on Saturday, Philippine officials said, but there were no initial reports of casualties or damage.
No tsunami warning was issued.
The aftershocks, recorded at 7.6 and 7.4 by the U.S. Geological Survery, and the initial 7.3 quake occurred at considerable depths of between 576 and 617 km (358 to 383 miles) southwest of Cotabato on the southern island of Mindanao.
"The earthquake was too deep to generate waves and create damage," Renato Solidum, head of the Philippine Institute of Volcanology and Seismology, told Reuters. He said it was only felt at intensity 2 in most parts of Mindanao.
"The earthquake was not caused by movement in an active faultline, but by the sinking of the Moluccas plate. It has been sinking for some time, causing major tremors, but these were too deep to cause any damage. There's nothing to worry about."
He said the Philippine body had a different system of calaculating magnitude and had reported the quake and aftershocks at 6.9, 6.8 and 6.7 respectively.
A quake of over 7.0 magnitude can cause widespread damage.
The earthquake struck at 6.08 am (2208 GMT) about 103 km (64 miles) southwest of Cotabato. The two aftershocks occurred within just over an hour.
People in Cotabato, where the tremor was felt at intensity 2, were unaware of the quake.
"There was no shaking, I never felt anything," hotel worker Jap Rabino told Reuters. "It's business as usual."