<P> The 2011 earthquake off the Pacific coast of Tōhoku ( 東北 地方 太平洋 沖 地震 , Tōhoku - chihō Taiheiyō Oki Jishin ) was a magnitude 9.0 -- 9.1 ( M ) 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 29 km ( 18 mi ) . The earthquake is often referred to in Japan as the Great East Japan Earthquake ( 東日本 大震災 , Higashi nihon daishinsai ) and is also known as the 2011 Tōhoku earthquake , and the 3.11 earthquake . It was the most powerful earthquake ever recorded in Japan , and the fourth 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 , traveled up to 10 km ( 6 mi ) inland . The earthquake moved Honshu ( the main island of Japan ) 2.4 m ( 8 ft ) east , shifted the Earth on its axis by estimates of between 10 cm ( 4 in ) and 25 cm ( 10 in ) , increased earth 's rotational speed by 1.8 μs per day , and generated infrasound waves detected in perturbations of the low - orbiting GOCE satellite . Initially , the earthquake caused sinking of part of Honshu 's Pacific coast by up to roughly a metre , but after about three years , the coast rose back and kept on rising to exceed the original height of the coast . </P>
how tall was the tsunami that hit japan
40.5 metres ( 133 ft )