An earthquake measuring 6.4 on the Richter scale jolted Indonesia's north Sulawesi island on Sunday, but there were no immediate reports of casualties or damage, the meteorology agency said. The quake struck at a depth of 32 km (20 miles), and the epicentre was 91 km (56 miles) southwest of Gorontalo town, said Suhardjono, an agency official. The agency did not issue a tsunami warning. Indonesia suffers frequent earthquakes, being located in an active seismic region where several tectonic plates meet. (Reporting by Telly Nathalia, writing by Karima Anjani, editing Sugita Katyal)