The submarine earthquake occurred at a focal depth of 49 km ( 30.4 mi ) in the western Pacific Ocean on 7 April 2011 at 14:21 UTC , approximately 66 km ( 41 mi ) east of Sendai . The quake was a direct result of thrust faulting on or near the subduction zone plate boundary between the Pacific and North American Plates . Initially estimated at a magnitude of 7.4 , the tremor was felt in several areas near the east coast of Honshu as an aftershock of the 11 March magnitude 9.0 megathrust Tōhoku earthquake . The aftershock sequence of this event is ongoing since 11 March , and includes over 58 earthquakes of magnitude 6.0 or greater up until 7 April 2011 , with only two others of magnitude 7.0 or greater
Tōhoku earthquake
2011 Tōhoku earthquake and tsunami
April 2011 Miyagi earthquake