A volcano erupted on a small island in southern Japan on Friday, spewing black clouds of ash and rock into the sky and prompting authorities to tell residents to evacuate the island.

No injuries were reported after Mount Shindake erupted about 10 am local time in spectacular fashion, sending a dense mixture of rock and hot gases toward the sea, the Japan Meteorological Agency reported.

The agency raised the volcano alert for Kuchinoerabu Island, where Shindake is located, to level 5, the highest on its scale. Shindake also erupted in August for the first time since 1980.

A military helicopter was sent to survey the island and assess damage. Chief government spokesman Yoshihide Suga told reporters in Tokyo that the Coast Guard had sent a ship to help evacuate the residents.

Nobuaki Hayashi, a local village chief, said about 120 of the island's 137 residents were gathered at an evacuation facility.

"There was a really loud, 'dong' sound of an explosion, and then black smoke rose, darkening the sky," he told the national broadcaster NHK. "It smelled of sulfur."

Hayashi said a few people on the island were still unaccounted for. One person, who lives in an area that is generally off-limits, was to be evacuated by boat as he could not travel safely to the shelter by land.

"The skies here are blue, but smoke is still rising to the west," he said.

Kuchinoerabu is 80 km southwest of the main southern island of Kyushu. A heavily forested, mountainous island bordered mostly by rocky cliffsides, it is a national park supported by tourism and fishing.

Footage from NHK showed the mountain shrouded in light gray ash as the clouds from the eruption cleared.

Kuchinoerabu usually can be reached only by a once-a-day ferry from Yakushima Island, 12 km to the east, which has an airport and a population of more than 13,000 people.

Japan, which sits atop the Pacific "Ring of Fire", has dozens of volcanoes and is frequently jolted by earthquakes.

In March 2011, a magnitude-9 earthquake rocked northeastern Japan, triggering a tsunami that killed more than 18,500 people and ravaged much of the northern Pacific coast.

Authorities recently closed part of a popular hot springs about 80 km from Tokyo because of fears Mount Hakone, which sits to the southeast of Mount Fuji, might erupt.

The eruption in September of another volcano, Mount Ontake in central Japan, killed 57 people.

Setsuya Nakada, a professor at Tokyo University, told NHK that the eruption on Kuchinoerabu was stronger than Mount Ontake's.

Since the 2011 disasters, "this sort of activity has continued", Nakada said, when asked if more eruptions were likely on the island. "Probably the eruptions will continue."