The 2011 Tōhoku earthquake and tsunami occurred in 2011, striking Japan on March 11. The undersea megathrust earthquake began at 2:46 p.m. Japan Standard Time off the northeastern coast and lasted approximately six minutes.
The earthquake, initially measured at magnitude 9.0 and later revised by the USGS to 9.1, was the strongest ever recorded in Japan. Movement along the subduction zone lifted the seafloor and displaced a huge volume of seawater, generating a tsunami that devastated coastal communities across Tōhoku.
The waves reached heights of more than 40 metres in parts of Iwate Prefecture and travelled far inland around Sendai. The disaster caused nearly 20,000 deaths, widespread destruction, and the Fukushima Daiichi nuclear accident. A common mix-up is confusing the event with the 2004 Indian Ocean tsunami or the 2010 Chile earthquake; the Tōhoku disaster is firmly associated with 2011.