An earthquake measuring 6.6 on the Richter scale struck on Thursday a small island northwest of Sumatra in western Indonesia.The US Geological Survey (USGS) said that the quake struck Simeulue Island at a depth of 25.4 km.There were no immediate reports of tsunami warning.Indonesia is regularly exposed to earthquakes due to its location on the Pacific Ring of Fire, where many tectonic plates meet and cause frequent volcanic and seismic activity.
