TOKYO (AP) _ Two earthquakes struck Japan on Friday, temporarily cutting off water to homes but injuring no one.

A pre-dawn 6.1 magnitude earthquake shook Tokyo and nearby areas, cutting off the water supply to nearly two dozen homes.

A second quake with a preliminary magnitude of 5.5 struck at 2:16 p.m.

The second quake was centered 25 miles under the seabed in the Pacific Ocean about 85 miles southeast of Tokyo, the Meteorological Agency said.

The magnitude 6.1 quake, which hit at 3:39 a.m., was centered in waters off the coast of Ibaraki state, 70 miles northeast of Tokyo. It shook buildings for several seconds in Tokyo.

Shigeru Seki, an Ibaraki police spokesman, said some trains in the Tokyo area were temporarily stopped to check for possible damage to the tracks.

Japan is one of the most earthquake-prone countries in the world. Recently, a series of quakes has been shaking the Izu island chain near Tokyo, including a 5.1 magnitude quake on Thursday. The Meteorological Agency said Friday's temblors were unrelated to seismic activity on the islands.

Last Saturday, a 6.2 magnitude quake knocked down the walls of several homes on Niijima island, about 105 miles south of Tokyo. On July 1, a magnitude 6.4 earthquake killed a man in a landslide on the nearby island of Kozushima.