The Most Powerful Earthquake Ever Recorded in Japan

Tōhoku earthquake

On 11 March 2011, the Tōhoku earthquake with a magnitude 9.0–9.1 (Mw) hit north-eastern Japan and is to this date the most powerful earthquake ever recorded in Japan. A tsunami following the earthquake sent waves reaching heights of up to 40.5 meters towards the Daiichi Nuclear Power Plant in Fukushima. The active reactors automatically shut down but the tsunami disabled the emergency generators and led to three nuclear meltdowns, hydrogen-air explosions, and the release of radioactive material.

The most powerful earthquake ever recorded in Japan

The fourth most powerful earthquake in the world (since modern record-keeping began in 1900)

The tsunami waves reached heights of up to 40.5 metres (133 ft)

The earthquake moved Honshu (the main island of Japan) 2.4 m (8 ft) east

Shifted the Earth on its axis by estimates of between 10 cm (4 in) and 25 cm (10 in)

Increased earth’s rotational speed by 1.8µs per day

Life has still not returned.

Residents within a 20-km radius of the Fukushima Daiichi Nuclear Power Plant were evacuated. Today more than 6 years after the event, life has still not returned to normal. Roads have been rebuilt and electricity has been restored but the operator for the nuclear power plant faces a cleanup that some say could take almost 40 years to complete. In addition, atmospheric radiation levels of 530 sieverts an hour have been detected – that’s 100s of times more than a lethal dose for humans and even brief exposure would be fatal. Thankfully, there have been no recorded deaths as a result of the nuclear disaster, but over 100,000 people have yet to return to their homes.

The Japanese government and the operating company of the plant have been heavily criticized and in 2017 a Japanese court ruled that negligence by the Japanese government had led to the Fukushima disaster. Compensation has been granted to 137 people who were forced to flee their homes following the accident and initiatives around thyroid screening have been put in place to monitor long-term effects of the radiation.

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Fishing is still prohibited but the restricted zone has recently been decreased from 20 km to 10 km. Residents have not received any education regarding radiation and therefor many find it difficult to make the decision on when it’s safe to return.

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