An earthquake measuring 5.3 Richter scale struck off Aceh province of Sumatra island in Indonesia on Wednesday, the Meteorology and Geophysics Agency reported here. The quake jolted at 13:20 p.m. Jakarta time (0620 GMT) with epicenter at 349 km northwest Simeulu island of Aceh and with the depth at 24 km under sea bed, the agency said. Indonesia is vulnerable on earthquake as it sits on a vulnerable quake-hit zone so called \"the Pacific Ring of Fire,\" where two continental plates meet that frequently caused seismic and volcanic movement in the country homed by 129 active volcanoes.