Japan (2011) earthquake and tsunami

Japan (2011) earthquake and tsunami
Name	Tōhoku earthquake and tsunami
Caption	Coastal damage after the disaster in Miyagi Prefecture
Date	11 March 2011
Magnitude	9.0–9.1 M_w
Depth	29 km
Countries affected	Japan
Fatalities	15,899 confirmed
Injured	6,157
Missing	2,529

Contents

Japan (2011) earthquake and tsunami The disaster began with a megathrust Tōhoku earthquake that struck off the coast of Honshū on 11 March 2011, generating a transoceanic tsunami that devastated coastal areas of Miyagi Prefecture, Iwate Prefecture, and Fukushima Prefecture, and triggered the Fukushima Daiichi nuclear disaster. The event produced wide-reaching humanitarian, economic, and geopolitical effects that involved organizations such as the United Nations, Red Cross Society, and national responses from United States and Australia, while prompting scientific reassessment by institutions like the United States Geological Survey and the International Seismological Centre.

Background

Japan lies along the Pacific Ring of Fire where the Pacific Plate, North American Plate, Philippine Sea Plate, and Eurasian Plate interact, producing recurrent megathrust earthquakes like the 1896 Sanriku earthquake and the 1946 Nankai earthquake, as well as modern seismic studies by University of Tokyo and the Japan Meteorological Agency. Prior to 2011, hazard mitigation programs such as the Japan Self-Defense Forces disaster drills, International Atomic Energy Agency safety reviews, and coastal defenses in cities like Sendai and Ishinomaki reflected lessons from tsunamis recorded in the Jōgan tsunami and research by the Geological Survey of Japan.

At 14:46 JST on 11 March 2011 a magnitude 9.0–9.1 undersea megathrust event occurred on the subduction interface between the Pacific Plate and the North American Plate approximately 130 km east of Sendai, producing intense ground motions recorded by networks including the Hi-net seismic array and the USGS National Earthquake Information Center. The rupture propagated over 400 km along the trench, generating aftershocks cataloged by the Japan Meteorological Agency and felt in metropolitan centers such as Tokyo, Yokohama, and Sapporo, disrupting rail services on lines like the Tohoku Shinkansen and causing tsunami advisories from agencies including the Pacific Tsunami Warning Center.

The earthquake generated a tsunami with run-up heights exceeding 40 meters in places along the Sanriku coast, inundating towns including Kesennuma, Rikuzentakata, and Minamisanriku, overtopping sea walls and breaching defenses designed after earlier events like the 1896 Sanriku earthquake. Tsunami propagation was observed across the Pacific Ocean with impacts reported in Hawaii, California, Chile, and New Zealand, monitored by systems run by the National Oceanic and Atmospheric Administration and modeled by research centers at Woods Hole Oceanographic Institution and International Oceanographic Commission.

The disaster caused widespread loss of life and displacement, with confirmed deaths concentrated in Miyagi Prefecture, Iwate Prefecture, and Fukushima Prefecture, and large-scale evacuations to shelters managed by municipal authorities in Sendai, Mito, and Fukushima City. Humanitarian response involved international actors including Médecins Sans Frontières, International Federation of Red Cross and Red Crescent Societies, and military assets such as the United States Navy and the Japan Maritime Self-Defense Force, while demographic studies by National Institute of Population and Social Security Research examined long-term population impacts and migration to urban centers like Tokyo.

Infrastructure damage extensively affected ports such as Port of Sendai, nuclear plants like Fukushima Daiichi Nuclear Power Plant, transportation networks including the Senseki Line and highways, and energy supplies managed by utilities such as Tokyo Electric Power Company and Tohoku Electric Power Company. Economic effects rippled through global supply chains involving manufacturers like Toyota, Sony, and Nissan, impacted commodity markets in London and New York Stock Exchange, and prompted fiscal responses from the Bank of Japan and the Ministry of Finance (Japan).

The earthquake and tsunami led to loss of power and cooling at the Fukushima Daiichi Nuclear Power Plant, resulting in reactor meltdowns, hydrogen explosions, and release of radioactive materials, an event classified by the International Nuclear and Radiological Event Scale as level 7, comparable to the Chernobyl disaster. Response involved operators Tokyo Electric Power Company and oversight by the Nuclear Regulation Authority (Japan), with international assistance from the International Atomic Energy Agency, engineering support from firms like Areva, and research into radiological dispersion by institutions including National Institute of Radiological Sciences.

Immediate response included deployment of the Japan Self-Defense Forces, international search and rescue teams from countries such as the United States, Australia, and China, and logistical coordination through the United Nations Office for the Coordination of Humanitarian Affairs and Japan Red Cross Society. Long-term recovery programs encompassed reconstruction projects led by the Ministry of Land, Infrastructure, Transport and Tourism, revitalization initiatives in municipalities such as Ishinomaki and Kesennuma, and policy reforms including nuclear safety revisions informed by the Fukushima Nuclear Accident Independent Investigation Commission and legislative changes in the Diet of Japan.