A magnitude-6.0 earthquake shook the Tokyo area Saturday, injuring at least 27 people, rattling buildings across the sprawling capital and temporarily suspending flights and train services.

The earthquake struck at 4:35 p.m. (3:35 a.m. EDT) and was centered about 55 miles underground in Chiba prefecture (search), just east of Tokyo, Japan's Meteorological Agency said. There was no danger of tsunami (search), the agency said.

The quake was the strongest to hit the capital since 1992 as measured on Japan's sliding scale of tremor intensity, the Kyodo News (search) agency reported.

The quake injured at least 27 people, including five people hit by a falling signboard at a supermarket in neighboring Saitama prefecture, Kyodo said. There were some 50 cases of people briefly trapped in elevators.

The Meteorological Agency gave the quake an initial reading of magnitude 5.7 but later upgraded its strength.

Power in eastern Japan was not disrupted but Tokyo's main international airport in Narita briefly closed its runways. Bullet trains between Tokyo and western coastal areas also were suspended, but air and train services resumed later in the evening.

Tokyo has not suffered a major earthquake since a 1923 temblor that killed 140,000 people, but many experts say the capital is overdue for another strong quake. A government report last year said a powerful earthquake under Tokyo could kill as many as 12,000 people and destroy 850,000 homes.

Japan sits at the juncture of four tectonic plates, or moving slabs of the earth's outer crust, and is one of the world's most quake-prone regions.

A magnitude-5 quake can damage homes and other buildings if it is centered in a heavily populated area. A magnitude-6.8 temblor struck the northern Japanese prefecture of Niigata last October, killing 40 people and injured more than 2,700.