JAKARTA - A strong offshore earthquake registering 5.4 on the Richter scale hit the eastern coast of central Sumatra Monday but there were no immediate reports of damage or casualties, the meteorology office said. The earthquake, which hit at 4:16 pm (0916 GMT), was centered 46 kilometers (29 miles) under the floor of the Indian Ocean, some 129 kilometers (80 miles) southwest of Bengkulu city, agency official Hardiatno said in Jakarta. Hardiatno said that the quake was felt in Bengkulu but that there were no reports of damage or casualties in the city. The Hong Kong observatory registered the quake at 6.0 on the Richter scale.Indonesia sits on the Pacific “Ring of Fire”, where the meeting of continental plates means seismic activity is common. A geographical faultline runs parallel to the Indonesian island of Sumatra and tectonic activities along it have repeatedly led to strong earthquakes.