Indonesian Volcano Spews Lava, Ash

Updated Dec. 31, 2013 3:58 a.m. ET

Mount Sinabung erupts on Tuesday. Agence France-Presse/Getty Images

JAKARTA, Indonesia—A volcano on Indonesia’s Sumatra island is spewing lava and ash, while its lava dome has partially collapsed, offering experts some sign the volcano may be nearing the end of a monthslong period of heightened activity.
Mount Sinabung in North Sumatra has forced nearly 20,000 people from their homes since sporadic eruptions began in September. In late November, as the volcano’s lava dome swelled and the mountain continued to eject ash, experts placed it under the nation’s highest alert status.
On Monday afternoon, Mount Sinabung released the first of several lava flows, which continued on Tuesday. Meanwhile, its lava dome suffered dozens of avalanches, according to the National Agency for Disaster Management. The lava reached more than two kilometers (1.2 miles) down the mountain.
Eruptions of ash and gas clouds accompanied the release of lava, while several tremors shook the area, one of which lasted nearly five minutes.

Hot lava runs down the volcano’s slopes. Agence France-Presse/Getty Images

“I think it’s almost at the end of its activity,” said Surono, special staff to the energy minister and one of the nation’s foremost volcano experts, who like many Indonesians uses only one name. “The lava dome began forming in early November, and now it’s collapsed many times.”
Ash clouds reached seven kilometers into the air on Monday, but had fallen to half that less than a day later.
The disaster agency said winds pushed the ash clouds to the east and southeast, away from Indonesia’s third-largest city of Medan. The provincial capital of North Sumatra, home to more than two million people, sits 50 kilometers to the northeast.
In 2010, Sinabung came to life after lying dormant for a century, forcing the evacuation of around 12,000 villagers.
This year, thousands of people have been displaced for more than a month, with the disaster agency calling on families not to return to homes within five kilometers of the mountain.
Mr. Surono said Sinabung appeared to have less energy than Merapi, one of Indonesia’s most active volcanoes, in central Java, where lava flows extended for more than 15 kilometers at the height of its activity in 2010. Mount Merapi also expelled ash up to twice as high into the sky, he said.
Those eruptions, over a series of months, killed more than 300 people and displaced hundreds of thousands.
But in the case of Sinabung, “I cannot predict” what will happen, said Sutopo Purwo Nugroho, spokesman for the disaster agency. He said government scientists lack a deep understanding of the volcano’s characteristics, given its lengthy period of inactivity before 2010.
Mr. Nugroho also cautioned that eruptions could occur even after the release of lava flows, as they did in the case of Merapi, he said.
Indonesia has many active volcanoes. The country sits on the fault lines of the Pacific Ring of Fire, which sees frequent earthquakes and volcanic activity.
The archipelago is home to some of the world’s most famous volcanic eruptions, including the Mount Toba super-eruption around 74,000 years ago in North Sumatra that created what is today the world’s largest volcanic lake, and the eruption of Mount Krakatau, which lies west of Java, in 1883.
Write to Ben Otto at ben.otto@wsj.com

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