Home › Landforms › Great Earthquakes
The 2011 Tōhoku Earthquake and Tsunami
Japan's strongest recorded earthquake, whose tsunami killed nearly 16,000 people and caused the Fukushima Daiichi nuclear accident
At 2:46 p.m. on March 11, 2011, the strongest earthquake ever recorded in Japan struck off the Pacific coast of the Tōhoku region in northeastern Honshu. The magnitude 9.0 to 9.1 shock lasted about six minutes and moved parts of the seafloor by 50 meters or more. Japan's earthquake early warning system sent alerts seconds before the strongest shaking, and the country's strict building codes kept most structures standing. The tsunami that followed proved far deadlier. Waves over 10 meters high, with run-up near 40 meters in places, overtopped seawalls and swept through coastal towns in Iwate, Miyagi and Fukushima. They also disabled the Fukushima Daiichi nuclear plant, leading to three reactor meltdowns and the evacuation of more than 150,000 residents.
The epicenter lay about 70 kilometers east of the Oshika Peninsula, at a depth of about 29 kilometers, on the Japan Trench subduction zone, where the Pacific Plate sinks beneath northern Honshu at about 8 centimeters a year. Geologists assign the overriding plate either to the Okhotsk Plate or to the North American Plate. The rupture extended about 500 kilometers along the trench. The coast of Honshu shifted east by up to about 5 meters and sank by up to about a meter. The tsunami reached the shore within about 30 minutes. The highest run-up, 40.5 meters, was measured near Miyako in Iwate Prefecture. The waves destroyed the port towns of Rikuzentakata, Minamisanriku and Ōtsuchi, flooded about 560 square kilometers of land, and crossed the Pacific to Hawaii, California and Chile.
According to Japan's National Police Agency, 15,901 people died and 2,519 remained missing as of March 2026, fifteen years on, and the government counts about 3,800 further disaster-related deaths, mostly among evacuees. Most victims drowned, and more than half were 65 or older. The World Bank estimated the damage at about 235 billion US dollars, making it the costliest natural disaster on record. At Fukushima Daiichi, the loss of cooling led to the most serious nuclear accident since Chernobyl, and decommissioning is expected to last decades. Japan built higher seawalls along much of the coast, raised the ground in rebuilt towns and revised its tsunami forecasts. The quake also showed that the Japan Trench could produce larger earthquakes than many scientists had assumed.