TOKYO (AP) _ A moderately strong earthquake, one of a series of recent temblors, rattled a string of volcanic islands off Tokyo on Wednesday morning. No damage or injuries were reported.

The quake had a preliminary magnitude of 5.1 and was centered about six miles below the ocean floor off Miyakejima island, the Meteorological Agency said. It struck at 3:36 a.m.

Miyakejima, with about 4,000 residents, is 120 miles south of Tokyo.

Seiji Asanuma, a municipal official, said an evacuation order for an estimated 100 households on the northeast of the island was issued as a precaution against possible landslides because of the quake and recent heavy rains. Earlier Wednesday, authorities on Kozushima island near Miyakejima ordered 627 residents to evacuate.

Wednesday's quake was among thousands that have hit the Izu islands chain in recent weeks since 2,670-foot high Mount Oyama on Miyakejima began volcanic activity June 26.

About half of the residents on Miyakejima were temporarily evacuated last month, but they were all allowed to return home after fears of a volcanic eruption subsided

Japan is one of the world's most earthquake-prone countries as it sits atop four tectonic plates, slabs of land that move across the earth's surface.