TOKYO (AP) _ A volcano on the island of Miyakejima off Tokyo erupted twice Friday, spewing dark smoke into the sky and forcing nearly 100 residents to evacuate.

The evacuation order was issued to protect residents in the northern part of Miyakejima from falling ashes and not from possible lava flow, said Miyakejima official Sumio Enomoto.

Seiji Asanuma of the island's municipal office said there were no immediate reports of damages or injuries from either eruption at the 2,670-foot Mount Oyama.

Mount Oyama first spewed ash and smoke at around 4:14 a.m., scattering ash in wide areas of the island, 120 miles south of Tokyo.

The Meteorological Agency said the eruption ceased at around 11:10 a.m. But the volcano erupted again at 3:50 p.m., shooting smoke as high as 3,280 feet with several loud explosive noises.

Mount Oyama last erupted Saturday, briefly coughing up yellowish smoke. The agency warned similar eruptions may continue because of ongoing earthquakes and crust movements below its peak.

Miyakejima, home to about 4,000 people, and other neighboring islands have been rocked by more than 17,500 earthquakes in recent weeks, including about 5,480 quakes that are strong enough to be felt by humans.

On July 1, a 6.4-magnitude earthquake killed a fisherman in a car buried under fallen rocks on the island of Kozushima, 15 miles northwest of Miyakejima.

The new evacuation comes after an evacuation order affecting more than 2,000 people was lifted last month.

Experts had said there was danger of an eruption. The order was lifted after they found that magma was flowing away from the island under the seabed.

The Miyakejima volcano has erupted several times in the past 60 years, including in 1983, but the blasts usually came quickly and were over in a few days.

No one was killed or injured in the 1983 eruption because residents were evacuated in time. Eleven people died in a 1940 eruption.

Separately, 502 people from 338 households in a hot-spring resort near Mount Usu, an active volcano in northern Japan, were allowed to return home Friday after 102 days of evacuation, said Yukio Shinohara of the Abuta town office.

The families were among more than 13,000 people evacuated in March, when Mount Usu erupted for the first time in 22 years.

Many have been allowed to return home. But 1,432 people are still staying at public facilities or at relatives' homes.