What was the exact date of the massive earthquake and tsunami that struck Japan in 2011?

The massive earthquake and tsunami that struck Japan occurred on March 11, 2011. Known as the 2011 Tōhoku earthquake and tsunami, the undersea megathrust earthquake began at 14:46:24 Japan Standard Time off northeastern Honshu.

The earthquake had a moment magnitude of 9.0 in initial assessments and was later upgraded by the United States Geological Survey to 9.1. It lasted approximately six minutes and generated a devastating tsunami along Japan’s Pacific coast. Waves reached heights of up to about 40.5 meters in Miyako, Iwate Prefecture, and traveled far inland in the Sendai region.

The disaster is often called 3.11 in Japan, using the numerical date. It caused enormous loss of life and damage, including the Fukushima Daiichi nuclear accident. The earthquake was the strongest ever recorded in Japan and among the most powerful earthquakes measured worldwide since modern seismography began.

A common confusion is with major aftershocks on April 7 and April 11, 2011. Those were later events; the main earthquake and tsunami occurred on March 11.