JAKARTA ~ A moderate 5.7-magnitude earthquake struck off Sulawesi on Monday, seismologists said, but there were reports of casualties or damage and no tsunami warning.

The quake, which hit at 7:03am, was centered 24 kilometers southwest of Palu in Central Sulawesi and at a depth of 30 kilometers under the seabed, the Meteorology and Geophysics Agency said.

The archipelago sits on the so-called Pacific Ring of Fire where continental plates meet, causing frequent seismic and volcanic activity.