An earthquake measuring five on the Richter Scale again rocked Cilacap district, Central Java, on Friday morning at 10:16 Western Indonesia Standard Time, ANTARA reported today. There were no reports of casualties but the temblor shocked local residents. The Cilacap residents said the earthquake had jolted the area two times this week although the tremors were mild. The district's meteorology and geophysics agency chief Teguh Wardoyo said the quake's epicenter was located at 8.39 degrees southern latitude and 107.33 degrees eastern longitude. Indonesia lies in the "ring of fire" area which is vulnerable to earthquakes.