A moderately strong earthquake measuring 5.0 on the Richter scale jolted Tokyo and surrounding areas today, and four people were reported injured, two of them seriously.
A 74-year-old woman suffered head injuries after falling downstairs at her home in Tokyo during the quake, and a woman aged 94 suffered broken bones as she tried to get out of her house in Chiba, east of the capital, Kyodo news service reported.
Flights at Narita airport outside Tokyo were unaffected, but the city's Haneda Airport, which handles mostly domestic flights, closed its three runways for checks.
As buildings in the capital swayed, services on one local train line were halted and others reduced speed as a precaution.
Public broadcaster NHK said Shinkansen bullet train services between Tokyo and Odawara in nearby Kanagawa prefecture were halted after the earthquake but resumed after a brief stoppage. There were no warnings of tsunami tidal waves.
The focus of the quake, which struck at 4.30 p.m. (8.30 a.m. Irish time), was 80 km beneath the earth's surface east of Tokyo.