Tokyo - A strong quake shook buildings in Tokyo on Monday, setting off alarms and temporarily bringing the city's subway system to halt, AFP reporters in the Japanese capital 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 closed for staff to inspect for any damage. Neither was found to have been affected. Reporters said the quake developed as a series of vertical bounces as well as a side-to-side shaking.
The epicentre was located in the northern part of Saitama Prefecture, north of Tokyo. 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.
It also sparked a nuclear emergency at Fukushima when waves swamped the cooling systems of reactors. 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.
Rigid building codes and strict enforcement mean that even powerful quakes frequently do little damage to infrastructure.