Several thousand people fled their homes at the start of the month when the alert status was lifted, and the total number of evacuees now stands at 10,714, said the disaster agency.
The evacuees are sheltering in government buildings and places of worship in Kabanjahe town, around 10 kilometres (six miles) from Sinabung.
Volcanic activity remained high Tuesday, with Sinabung spewing out rocks and hot gas over a distance of three kilometres four times since early morning, said Armen Putra, head of the volcano observation post.
“We could still feel tremors. Ash one to two millimetres thick covered roads and homes located 15 kilometres away,” he said.
“It could take weeks before it eases, but for now, it is dangerous for people living nearby so we have recommended for them to evacuate.”
After Sinabung rumbled back to life in 2013, more than 10,000 people fled from nearby villages. Some have returned home but more than 6,000 of the original evacuees are still living in shelters.
The volcano has also had a devastating economic impact, with the disaster agency estimating it caused more than $100 million in damage last year and in 2013 in a broad range of areas, including infrastructure, farming and tourism.
Sinabung is one of 129 active volcanoes in Indonesia, which sits on the Pacific Ring of Fire, a belt of seismic activity running around the basin of the Pacific Ocean.
