11 March 2011: An earthquake measuring 9.0 in magnitude strikes 130 km (81 mi) east of Sendai, Japan, triggering a tsunami killing thousands of people. This event also triggered the second largest nuclear accident in history, and one of only two events to be classified as a Level 7 on the International Nuclear Event Scale. (Source)
The 2011 earthquake off the Pacific coast of Tōhoku (Japanese: 東北地方太平洋沖地震, Hepburn: Tōhoku-chihō Taiheiyō Oki Jishin) occurred at 14:46 JST (05:46 UTC) on 11 March. The magnitude 9.0–9.1 (Mw) undersea megathrust earthquake had an epicenter east of the Oshika Peninsula of Tōhoku. It is often referred to in Japan as the Great East Japan earthquake (東日本大震災, Higashi nihon daishinsai)[fn 1] and is also known as the 2011 Tōhoku earthquake, the Great Sendai earthquake, the Great Tōhoku earthquake, and the great earthquake of March 11.
It was the most powerful earthquake ever recorded in Japan, and the fourth most powerful earthquake in the world since modern record-keeping began in 1900. The earthquake triggered powerful tsunami waves that may have reached heights of up to 40.5 meters (133 ft) in Miyako in Tōhoku’s Iwate Prefecture, and which, in the Sendai area, traveled at 700 km/h (435 mph) and up to 10 km (6 mi) inland. Residents of Sendai had only eight to ten minutes of warning, and more than a hundred evacuation sites were washed away. The tsunami swept the Japanese mainland and killed over 15,000 people, mainly through drowning, though blunt trauma also caused many deaths. The latest report from the Japanese National Police Agency report confirms 15,899 deaths, 6,157 injured, and 2,529 people missing across twenty prefectures, and a report from 2015 indicated 228,863 people were still living away from their home in either temporary housing or due to permanent relocation.
The tsunami caused nuclear accidents, primarily the level 7 meltdowns at three reactors in the Fukushima Daiichi Nuclear Power Plant complex, and the associated evacuation zones affecting hundreds of thousands of residents. Many electrical generators ran out of fuel. The loss of electrical power halted cooling systems, causing heat to build up. The heat build-up caused the generation of hydrogen gas. Without ventilation, gas accumulated within the reactor containment structures and eventually exploded. Residents within a 20 km (12 mi) radius of the Fukushima Daiichi Nuclear Power Plant and a 10 km (6.2 mi) radius of the Fukushima Daini Nuclear Power Plant were evacuated.
Early estimates placed insured losses from the earthquake alone at US$14.5 to $34.6 billion. The Bank of Japan offered ¥15 trillion (US$183 billion) to the banking system on 14 March in an effort to normalize market conditions. The World Bank‘s estimated economic cost was US$235 billion, making it the costliest natural disaster in history. According to a 2020 study, “the earthquake and its aftermaths resulted in a 0.47 percentage point decline in Japan’s real GDP growth in the year following the disaster.” (Source)