An earthquake measuring 4.6 magnitude on the Richter scale struck off the coast of Okinawa Prefecture, southwest of Japan on Sunday.Japan Meteorological Agency said that the quake occurred at a depth of 10 km.There have been no reports of causalities or material losses as a result of the earthquake.Japan is located at the meeting point of four tectonic plates, making it particularly vulnerable to seismic activity. It is also home to 100 active volcanoes.In 2011, a 9.0-magnitude earthquake rocked Japan and triggered a tsunami, killed more than 15,000 people, and caused a disaster at Fukushima nuclear plant.Source: Qatar News Agency