A 5.6-magnitude undersea earthquake rocked the city of Gorontalo, the capital of the Gorontalo province in northern Sulawesi early Saturday, the Meteorology Climatology and Geophysics Agency (BMKG) said. The quake which struck at 00.32 local time with epicenter in the sea at a depth of 65 kilometers, was located 83 km southwest of the city of Gorontalo, ANTARA quoted the agency as saying today. No casualty and damage to the property had been immediately reported.