The Sakurajima volcano in southern Japan spewed large rocks as far 2.5 kilometres away after erupting on Sunday night, forcing dozens of people to leave the area.
Video footage on NHK public television showed orange flames near the crater and dark smoke with ash billowing high above the mountaintop in Kagoshima prefecture.
Japan’s Meteorological Agency raised the eruption alert to the highest level of five and advised 51 residents in two towns facing the volcano to leave their homes.
By Monday morning, 33 left for a nursing care facility in a safer part of the region, according to Kagoshima city authorities. NHK said other residents may have gone to other locations.
“We will put the people’s lives first and do our utmost to assess the situation and respond to any emergency,” deputy chief Cabinet secretary Yoshihiko Isozaki said. He called on residents to pay close attention to updates from local authorities to protect their lives.
There have been no reports of damage or injuries. The crater of the volcano was obscured by bad weather on Monday morning.
The met agency warned of the potential for falling volcanic rocks within three kilometres of the crater and possible flow of lava, ash and searing gas within two kilometres.
Agency official Tsuyoshi Nakatsuji said the chances of more explosive violent eruptions were low, but residents should still watch out for falling rocks, mudslides and pyroclastic flow, which is a mixture of rock fragments, gas and ash.
He also advised residents to close curtains and stay away from windows, which could be broken by the force of an eruption.
Sakurajima, on the main southern island of Kyushu, is one of Japan’s most active volcanoes and has erupted repeatedly. It used to be an island but became a peninsula following an eruption in 1914 that killed 58 people.
The volcano is about 1,000 kilometres south-west of Tokyo.