A rumbling volcano on Indonesia's Sumatra island spewed clouds of smoke and ash high into the air Friday, the latest in a series of violent eruptions.

Huge columns of smoke hung over Mount Sinabung and the surrounding area, including an elementary school where children played in the shadow of the towering volcanic cloud.

Activity levels have increased in the past week, with Sinabung shooting hot ash clouds into the sky dozens of times, according to the local volcano monitoring agency.

Despite the eruptions, local villagers continue their precarious existence.

The children were playing at a school in Neman Teran district, although officials say it is safe as the site is outside a four-kilometre (2.5-mile) danger zone around the crater where no one is supposed to set foot.

"It's safe for the school to be used," insisted local disaster agency chief Nata Nail.

Farmers continue tending to their crops and people in local towns put on masks to go shopping as ash rains down from the sky.

Sinabung roared back to life in 2010 for the first time in 400 years. After another period of inactivity it erupted once more in 2013, and has remained highly active since.

In May last year seven people died in one of Sinabung's eruptions, while in February 2014 an eruption left 16 people dead.

Indonesia is home to around 130 volcanoes due to its position on the "Ring of Fire", a belt of tectonic plate boundaries circling the Pacific Ocean where frequent seismic activity occurs.