Ibu erupted again on Friday morning, spewing a tower of volcanic ash 4,000m above its peak, the country’s geology agency head Muhammad Wafid said in a statement.
Authorities advised residents and tourists to stay out of the four-to-seven-kilometre exclusion zone and to wear a face mask in case of falling ash.
Ibu is one of Indonesia’s most active volcanos, erupting more than 21,000 times last year.
More than 700,000 people lived on Halmahera island as of 2022, according to official figures.
Indonesia, a vast archipelago nation, experiences frequent seismic and volcanic activity due to its position on the Pacific “Ring of Fire”.
Last month, Mount Ruang in North Sulawesi province erupted more than half a dozen times, forcing thousands of residents of nearby islands to evacuate.
Its status has since been lowered to the second-highest alert level.
