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 1257 hrs local time, 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."
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.