JAKARTA, June 3 (Xinhua) -- A 6.0-magnitude earthquake jolted Indonesia's western North Sumatra province on Monday, but was not potential for tsunami, the meteorology and geophysics agency said here.

The quake hit at 12:57 p.m. local time (0557 GMT), with the epicenter at 30 km southwest of Nias Selatan and the depth at 19 km under sea bed, an official in charge at the agency, Slamet Wijaya, said.

"There is no threat of tsunami from occurring, so that we did not issue warning for that," he told Xinhua over phone.

The intensity of the quake was felt at 3 MMI (Modified Mercalli Intensity) in Padang Sidempuan and Gunungsitoli, Wijaya added.

There were no preliminary reports of damage or casualty, he said.

An aftershock of 5.5-magnitude rocked the province seven minutes after the main shock, the official said.

Indonesia is prone to quakes as it lies on a vulnerable quake-impacted zone called "the Pacific Ring of Fire."