Mount Ruang, on the island of North Sulawesi, experienced at least five large eruptions on Wednesday, prompting the Center for Volcanology and Geological Disaster Mitigation to issue its highest-level alert. The crater emitted grayish-white smoke continuously Thursday that rose more than 1,600 feet (500 meters) above the mountain peak.

Authorities have ordered people to stay at least 3.7 miles (6 kilometers) away from the 2,378-foot (725-meter) mountain. More than 11,000 people living in the affected area were ordered to leave. In December 2018, Indonesia's Anak Krakatau volcanic island erupted and collapsed, losing about three-quarters of its volume and triggering a powerful tsunami that killed more than 400 people. An 1871 eruption on Mount Ruang also caused a tsunami.