The 2011 Tōhoku earthquake, officially named the Great East Japan Earthquake,[6][7] was a magnitude 9.0 (Mw) undersea megathrust earthquake off the coast of Japan that occurred at 14:46 JST (05:46 UTC) on Friday, 11 March 2011,[2][3][8] with the epicenter approximately 72 km (45 mi) east of...