The 2011 earthquake off the Pacific coast of Tōhoku (東北地方太平洋沖地震 Tōhoku-chihō Taiheiyō Oki Jishin?), often referred to in Japan as the Great East Japan Earthquake (東日本大震災 Higashi nihon daishinsai?)[fn 1] and also known as the 2011 Tohoku earthquake, and the 3.11 Earthquake, 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, with the epicentre approximately 70 kilometres (43 mi) east of the Oshika Peninsula of Tōhoku and the hypocenter at an underwater depth of approximately 30 km (19 mi). It was the most powerful known earthquake ever to have hit Japan, and the fifth most powerful earthquake in the world since modern record-keeping began in 1900. The earthquake triggered powerful tsunami waves that reached heights of up to 40.5 metres (133 ft) in Miyako in Tōhoku's Iwate Prefecture, and which, in the Sendai area, travelled up to 10 km (6 mi) inland. The earthquake moved Honshu (the main island of Japan) 2.4 m (8 ft) east and shifted the Earth on its axis by estimates of between 10 cm (4 in) and 25 cm (10 in), and generated sound waves detected by the low orbiting GOCE satellite.