Mount Ruang, a volcano in Indonesia, erupted on Tuesday, spewing fiery lava and ash thousands of feet into the night sky and forcing the evacuation of hundreds of people in the North Sulawesi province, according to the authorities and local news reports.
The volcano erupted at about 7:19 p.m. local time, Antara, the national news agency, reported. The country’s National Disaster Mitigation Agency said on Wednesday that more than 800 people in nearby villages were displaced by the eruption, many using ferries and taking shelter in churches and community centers.
The authorities said supplies such as mats, blankets, cleaning materials, and tents were needed, and that more shelters might be opening for people fleeing the volcano.
Indonesia is the world’s largest archipelago nation. It is spread across what is known as the Ring of Fire, where tectonic plates clash under the surface of the Pacific Ocean and spawn earthquakes and eruptions from volcanoes.
Mount Ruang is a stratovolcano, or a steep, conical volcano that has built up over years in layers from explosive eruptions of lava, rock fragments, ash and other properties.
“It is in a part of the world where there are a lot of active volcanoes,” said Dr. Tracy K.P. Gregg, who chairs the Department of Geology at the University at Buffalo.
Its last major eruption was in 2002, when the column of lava and ash that it spewed reached up to 17 miles, Dr. Gregg said.
She said the volcano in 2002 measured 4, a “large” volcano on the Volcanic Explosivity Index, a scale used to measure the strength of an eruption by looking at several factors, such as duration, ash volume and plume height. Mount Pinatubo in the Philippines in 1991 measured 6 on the index. Mount St. Helens in the United States in 1980 measured 5.
“So it is a little bit smaller than that,” she said of Mount Ruang. Right now, it is not as violent as the previous eruption, she added, but the volcano cannot be fully assessed while it is in progress.
More than 300 volcanic earthquakes were detected over a period of at least two weeks preceding the eruption of Mount Ruang.
It is not immediately clear why the volcano erupted when it did. “Every volcano has its own personality,” she said.
In the past few years, several volcanoes in Indonesia have erupted. In December, 2023, the bodies of 11 hikers were found on the slopes of Mount Marapi on the island of Sumatra, after an eruption that spewed an ash column of nearly 3,000 meters — about 10,000 feet high.
