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.
Sagami Trough because of the proximity to a population center (with over 36 million living in Tokyo's metro area, with a total of 43 million living in the Kanto Region) and the magnitude the Sagami Trough can create. The Sagami Trough megathrust generated the 1703 Genroku earthquake, which was the greatest rupture along the trough in the last thousand years, and the 1855 (Ansei) and 1923 (Great Kanto or Taisho) earthquakes. Sagami Trough The also Sagami Trench, Sagami Megathrust, or Sagami Subduction Zone is a long trough, which is the surface expression of the convergent plate boundary where the Philippine Sea Plate