2011 Tōhoku earthquake and tsunami 2011 Tōhoku earthquake and tsunami The 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 east of the Oshika Peninsula of Tōhoku and the hypocenter at an underwater depth of approximately . The earthquake is often referred to in Japan as the 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.
Imperial Japanese Navy Air Service and the first one to be completed as from the keel up. In the 1920s, the larger percentage of aircraft that were initially acquired and inducted into service, were land based seaplanes whose main tasks were reconnaissance and anti-submarine patrols. The Japanese had drawn up plans for the formation of 17 squadrons of these aircraft, but budgetary constraints limited the units to eleven until 1931. Under the terms of the Washington Naval Treaty two incomplete capital ships were allowed to be rebuilt as carriers, for the Japanese; and . However, "Amagi" was damaged during the Great Kanto earthquake in 1923