Sharp increase in Mount Sinabung’s activity prompts highest alert, 6 000 evacuating

A significant increase in risk estimates caused by sharp increase in activity at Indonesia's Sinabung volcano over the last two days prompted officials to raise the alert level back to highest (4/4) on Wednesday, June 3, 2015 and order evacuation of 6 000 nearby residents living within a 7-km radius.

"The lava dome at Sinabung has grown in volume to more than 3 million cubic metres, making it unstable,"  Sutopo Purwo Nugroho, Head of Data Information and Public Relations BNPB said.

"There is a risk for the dome collapse followed by pyroclastic flows as far as 7 kilometres to the SE. 2053 families, or 6179 people, living on the southeastern slope of the volcano are affected by the evacuation order," Sutopo said.

Mount Sinabung first erupted on August 27, 2010 after about 129 years of sleep. That eruptive phase lasted for about a month, until September 18, after which the volcano was quiet for 3 years (-/+ few days).  An unconfirmed eruption was noted in 1881, and solfataric activity was seen at the summit and upper flanks in 1912, but there are no recorded historical eruptions prior to explosive eruptions during August-September 2010.

Explosive eruption on September 15, 2013 started a new, intense and already deadly eruptive phase which is still in progress. 16 people were killed and tens of thousands were temporarily displaced early last year.

Date acquired February 6, 2014. Image credit: NASA / Earth Observatory – EO-1 ALI

Date acquired June 7, 2013. Image credit: NASA / Earth Observatory – EO-1 ALI

"It is unknown how long the eruption of Mount Sinabung will last," Sutopo said. "This phenomenon is similar to eruption of Mount Unzen [Unzendake] in Japan."

Unzendake was quiet for 192 years until November 18, 1990, when it entered eruptive phase that lasted almost 5 years.

Featured image: NASA / Earth Observatory – EO-1 ALI.