Mount Sinabung volcano spews lava and ash during an eruption seen from Tiga Pancur village in Karo.
Photograph: Antara Foto/Reuters
Mount Sinabung is a Pleistocene-to-Holocene stratovolcano of andesite and dacite in the Karo plateau of Karo Regency, North Sumatra, Indonesia, 25 miles from the Lake Toba supervolcano.
Many old lava flows are on its flanks and the last known eruption, before recent times, occurred in the year 1600.
Solfataric activities were last observed at the summit in 1912; recent documented events include an eruption in the early hours of 29 August 2010 and eruptions in September and November 2013, January, February and October 2014.
Between 2013 and 2014 the alert for a major event was increased with no significant activity.
On 2 June 2015 the alert was again increased, and as of 26 June 2015 at least 10,000 people have been evacuated, fearing a major eruption.
The long eruption of Mount Sinabung is similar to Mount Unzen in Japan, which erupted for 5 years after lying dormant for 200 years.