An earthquake with the magnitude of 5.5 jolted Sulawesi island of Indonesia on Tuesday morning, the Meteorology and Geophysics Agency reported here.The quake struck at 08:20 a.m. Jakarta time (0120 GMT) with the epicenter at 197 km southeast Melonguane of North Sulawesi and with the depth of 111 km, the agency said. Indonesia is vulnerable to earthquake as it sits on a vulnerable quake-hit zone, the so called \"the Pacific Ring of Fire, \" where two continental plates, stretching from Japan to western hemisphere, meet and frequently caused seismic and volcanic movement in the country homed by 129 active volcanoes.The U.S. Geological Survey said the quake was 5.3 magnitude.