Source: Wikipedia

On March 11, 2011, at 05:46 UTC, a tsunami and earthquake in Thoku, Japan, struck. A tsunami was produced by the underwater megathrust earthquake, which had a duration of around six minutes and had its epicenter in the Pacific Ocean 72 kilometers (45 miles) east of the Oshika Peninsula in the Thoku region. Among other titles, it is occasionally referred to as the "Great East Japan Earthquake" in Japan. The disaster is frequently referred to as 3.11 in both Japanese and English.

It was the fourth-strongest earthquake in the globe since the start of modern record-keeping in 1900 and the strongest earthquake ever recorded in Japan. Strong tsunami waves were produced by the earthquake, which may have reached heights of up to 40.5 meters (133 feet) in Miyako in the Iwate Prefecture of Thoku. In the Sendai area, these waves moved at speeds of up to 700 km/h (435 mph) and as far as 10 kilometers (6 miles) inland. Only eight to ten minutes of warning were given to Sendai residents, and more than a hundred evacuation points were destroyed.

Rescue efforts were significantly hampered by the tsunami's snowfall and freezing temperatures; for example, Ishinomaki, the city with the highest death toll, was at 0°C (32°F) when the tsunami struck. A report from 2015 showed 228,863 people were still living away from their home in either temporary accommodation or due to permanent relocation. The official statistics issued in 2021 recorded 19,747 deaths, 6,242 injuries, and 2,556 people missing.

The meltdowns of three of the reactors at Fukushima Daiichi, the release of radioactive water into Fukushima, and the related evacuation zones that affected hundreds of thousands of civilians were all brought on by the tsunami. The gasoline for many power generators ran out. Heat accumulated because the loss of electrical power prevented cooling systems from functioning. The accumulation of heat led to the production of hydrogen gas.

Gas built up inside the reactor containment structures without ventilation, finally exploding. The Fukushima Daiichi Nuclear Power Plant was 20 kilometers (12 miles) away, while the Fukushima Daini Nuclear Power Plant was 10 kilometers (6.2 miles) away. Residents in these areas were evacuated.

The insured losses from the earthquake alone were first estimated to be between $14.5 and $34.6 billion USD. On March 14, 2011, in an effort to restore market conditions, the Bank of Japan made a 15 trillion (US$183 billion) offer to the banking industry. The cost of the disaster was estimated by the World Bank to be US$235 billion, making it the most expensive natural disaster in history. A 2020 analysis found that Japan's real GDP growth fell by 0.47 percentage points in the year after the tragedy as a result of the earthquake and its aftereffects.

Three tsunami deposits have been found in the Holocene sequence of the Sendai plain, all formed within the last 3,000 years, suggesting an 800 to 1,100 year recurrence interval for large tsunamigenic earthquakes. The earlier 869 Sanriku earthquake, which has been estimated to have a magnitude of at least 8.4 Mw and also created a large tsunami that inundated the Sendai plain, was the mechanism of this megathrust earthquake. Given that more than 1,100 years had passed, it was estimated in 2001 that there was a substantial possibility that a sizable tsunami would strike the Sendai plain. In 2007, it was predicted that there would be a Mw 8.1–8.3 earthquake 99 percent of the time within the next 30 years.