Mount Sinabung (Indonesian: Gunung Sinabung) is a Pleistocene-to-Holocene stratovolcano of andesite and dacite in the Karo plateau of Karo Regency, North Sumatra, Indonesia, 25 miles from 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 (cracks where steam, gas, and lava are emitted) were last observed at the summit in 1912, other documented events include an eruption in the early hours of 29 August 2010 and eruptions in September and November 2013.
Most of Indonesian volcanism stems from the Sunda Arc, created by the subduction of the Indo-Australian Plate under the Eurasian Plate. This arc is bounded on the north-northwest by the Andaman Islands, a chain of basaltic volcanoes, and on the East by the Banda Arc, also created by subduction. Sinabung is an andesitic-dacitic stratovolcano with a total of four volcanic craters, only one being active.
November 2013 Eruption:
The volcano erupted again on November 5, 2013, for the third time in as many months on the western Indonesian island of Sumatra, forcing hundreds of villagers to evacuate, officials said. This volcano spewed a 7-km (4.3-mile) column of ash into the air, prompting authorities to impose a 3-km evacuation radius. The military helped evacuate 1,293 people from four villages around the volcano, which is 88 km from the provincial capital, Medan. The number of evacuees was expected to rise. No casualties were reported. About 14,000 people were forced the evacuate when the volcano showed signs of activity in September. Sinabung is one of nearly 130 active volcanoes in the World's fourth-most populated country, which straddles the "Pacific Ring of Fire". On November 11, 2013, a pyroclastic flow, a fast-moving avalanche of ash, lava fragments and air, was seen racing down the peak. Since then, the volcano has blasted out one to two ash explosions every day.