Since Sinabung began erupting in November, nearly 30,000 people have been displaced and more than $60 million of farmland has been damaged, the Wall Street Journal reported Thursday.
The evacuation zone is currently 3.1 miles to 4.3 miles down the mountain, but may increase to 6 miles if activity worsens, which would double the number of evacuees, government officials said.
Jhonson Tarigan, a district spokesman, said the area is relying on government aid, as well as donations from companies and individuals, the Journal reported.
"Supplies are sufficient, but we're worried they may not be enough as the numbers of displaced people keeps rising," he said.
Volcanologists have been studying Sinabung since 2010 when it erupted for the first time in centuries, but are still unsure how powerful it may be or when it will stop erupting, the newspaper said.
Meanwhile, evacuees, most of whom are farmers who have had to sell their livestock, are living in mosques, churches, and wedding halls that have been turned into evacuation centers.
"It's all ruined," said Rina Sitepo, whose coffee, cabbage and chili crops were covered in ash spewed by Sitepo.