What happened
At 14:46 on March 11, 2011, a magnitude-9.0 earthquake struck off the Tohoku coast — the most powerful ever recorded in Japan. It triggered a tsunami that reached heights of tens of meters, with run-up around 40 meters at the extreme. Nearly 20,000 people died or remain missing, the great majority in the tsunami.
Flooding disabled cooling at the Fukushima Daiichi nuclear plant, causing meltdowns rated at the highest severity level (INES 7) and the evacuation of well over 100,000 residents.
Background
The quake struck along the Pacific-plate subduction zone. Tsunami defenses were overwhelmed beyond their design assumptions.
Consequences
Reconstruction has run for more than a decade. The disaster prompted national reviews of nuclear policy and disaster planning, and March 11 joined September 1 in Japan’s calendar of remembrance.