A strong earthquake measuring 5.2 on the Richter scale shook Tokyo today, but there were no immediate reports of injuries or damage, Japan's Meteorological Agency said.
The focus of the tremor, which occurred at 11.42 a.m. (3.42 a.m. Irish time), was in Ibaraki prefecture, about 50 kilometres northeast of Tokyo, at a depth of 50 kilometres, the agency said. There was no risk of a tidal wave, it added.
The quake was powerful enough to keep high-rise buildings in Tokyo, designed to flex with tremors, swaying for about 30 seconds.
It forced the suspension of bullet train services to the north of Japan out of Tokyo, a JR East spokesman said.
Take-offs and landings at Tokyo's Narita and Haneda airport were temporarily suspended while the runways were checked for cracks, airport officials said, but flights resumed within minutes.
The quake's focus was about 25 kilometres east of Saitama Stadium 2002, where one of the World Cup semi-finals is to be played on June 26th, and about 50 kilometres west of Ibaraki's Kashima stadium, which has already hosted all three of its scheduled World Cup matches.