Quake shakes buildings in Tokyo

A strong quake shook buildings in Tokyo today, setting off alarms and temporarily bringing the city's subway system to halt.

Scientists said there was no risk of a tsunami from the quake, which had a magnitude of 5.3, according to the US Geological Survey.

The Japan Meteorological Agency earlier put it at 5.6.

Both runways at Narita Airport, the main international gateway to Tokyo, were temporarily closed so staff could check for any damage. Neither was affected.

Alarms on mobile phones and in buildings sounded as the quake developed with a series of vertical bounces, as well as a side-to-side shaking.

The quake struck at a relatively shallow 35 kilometres, the USGS said, putting its epicentre just 34 kilometres north of the heaving metropolis of Tokyo, one of the most densely populated areas in the world.

National broadcaster NHK reported the effects were felt over a large area around the capital.

However, there were no immediate reports of injuries or any damage, including at any of the shuttered nuclear power stations in the region.

A massive 9.0 magnitude quake that struck off the country's northeast coast in 2011 generated a powerful tsunami that wreaked havoc in a wide area.

As well as killing more than 18,000 people, it destroyed thousands of homes and sparked a nuclear emergency at Fukushima when waves swamped reactor cooling systems.

Japan is located at the junction of a number of the earth's tectonic plates and experiences around a fifth of the planet's most powerful quakes every year.

But rigid building codes and strict enforcement mean even powerful quakes that might devastate other parts of the world frequently do little damage to Japanese infrastructure.