Earthquake and tsunami hit Japan

Japan has been hit by the most powerful earthquake in its recorded history, which triggered a tsunami that swept away towns along its north-east coast.

The earthquake, of magnitude 9, struck off the coast at 2.46pm local time on 11 March. Within an hour, waves of up to 10 metres had crashed ashore.

Towns destroyed

Pictures broadcast on television showed a wall of black water sweeping inland, carrying away cars, boats, houses and fields. Whole towns along the coast of the Tohoku region were destroyed.

Hundreds of people are confirmed dead, and thousands are missing. Officials fear the death toll will rise sharply as rescuers reach the worst-hit areas.

In Tokyo, more than 300 kilometres away, buildings shook violently and transport came to a standstill.

Nuclear emergency

The government has declared a nuclear emergency at the Fukushima Daiichi power station, where the cooling systems of reactors failed after the tsunami knocked out power. Tens of thousands of people living near the plant have been told to leave their homes.

Engineers are working to prevent the reactors from overheating, and there are fears of radiation leaks.

Warnings across the Pacific

Tsunami warnings were issued across the Pacific, including in Hawaii, the Philippines and the west coasts of North and South America.

A country prepared

Japan is one of the best prepared countries in the world for earthquakes, with strict building rules and regular drills. Experts say many lives were saved by these measures, but that nothing could have prepared for a tsunami on this scale.

World response

The Prime Minister, David Cameron, said Britain would do everything it could to help. A British search and rescue team is being sent to Japan.

The Foreign Office is trying to contact British people in the affected areas, and has set up a helpline.

The economy

Japan is the world's third largest economy, and the disaster has disrupted factories that supply parts to car and electronics makers around the world, including plants in Britain.

The Japanese prime minister, Naoto Kan, has set up an emergency headquarters to lead the response.