Japan island volcano
A volcano on the remote southern Japanese island of Kuchinoerabujima erupted on Friday, prompting authorities to order the evacuation of the island's residents. Pictured: Owakudani valley, a popular tourist spot on Mt. Hakone, is seen in Hakone, Kanagawa prefecture, May 6, 2015. Japanese authorities raised the volcanic alert for Mt. Hakone Wednesday. REUTERS/Kyodo

A volcano on the remote southern Japanese island of Kuchinoerabujima erupted suddenly on Friday, blasting plumes of black smoke high into the sky and prompting authorities to order the evacuation of the island's residents.

A pyroclastic flow of super-heated gas and rock flowed down the side of the peak and reached the ocean, NHK said, but there were no immediate reports of injuries to the island's roughly 150 residents.

The island is about 160 km (100 miles) south of Kyushu Electric Power's Sendai nuclear plant on Japan's southernmost main island of Kyushu.

It was not immediately clear if the eruption would affect the power company's hopes to restart the plant, which on Wednesday cleared the last step of the nuclear regulator's stringent safety hurdles introduced after the Fukushima Daiichi disaster in 2011.

Japan is one of the world's most seismically active nations and there has been an upsurge in volcanic activity in recent weeks.

Japan