A shallow 4.9-magnitude earthquake struck eastern Japan early on Wednesday, rattling one of the areas hit hardest by the March 11 quake and tsunami disasters. The quake struck three kilometres from the coastal town of Iwaki at a depth of 21 kilometres. No tsunami warnings were in effect and there were no immediate reports of damage. The Japan Meteorological Agency initially said the quake measured 5.1 on the Japanese seismic intensity scale, which runs to seven, but later downgraded the tremor to a 3.7.