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.
1923 Great Kantō earthquake in Yokosuka in compliance with the Washington Naval Treaty of 1922. The earthquake damaged the "Amagi" beyond repair, leading it to be scrapped, and the unfinished fast battleship "Kaga" was converted into an aircraft carrier in its place. In contrast to London, where typhoid fever had been steadily declining since the 1870s, the rate in Tokyo remained high, more so in the upper-class residential northern and western districts than in the densely populated working-class eastern district. An explanation is the decline of waste disposal, which became particularly serious in the northern and western districts when traditional methods of waste disposal