On 9 April 2013 the Darwin Volcanic Ash Advisory Centre in Australia reported a 4.3 km ash plume rising from Mount Karangetang, a volcano on Siau Island, one of the Sangihe Islands roughly 130 km north of Sulawesi and 260 km south of Mindanao in the Philippines. The plume drifted about 45 km to the northwest of the island. Karangetang, which is one of Indonesia's most active volcanoes, has been fairly quiet since December 2012, but began a new phase of volcanic activity on 4 April this year, with lava-flows on the flanks of the volcano and ash avalanches reaching as far as 2 km from the summit.
Karangatang is a 1784 m high stratovolcano (cone-shaped volcano) on the northern end of Siua Island. It has erupted 41 times since written records began on the island in 1675. The island is quite densely populated with around 22 000 permanent residents, and the volcano frequently causes problems for the islanders, having most recently caused fatalities in August 2010.
The Sangihe Island Arc is a chain of volcanic islands running between the northern tip of Sulawesi and the southern tip of Mindanao. The chain marks the boundary between the Molucca Plate to the east and the Sangihe Plate to the west, with the Molucca Plate being subducted beneath the Sangihe Plate. As the Molucca Plate sinks into the Earth it is heated by the friction and the heat of the planet's interior, causing it to partially melt. Some of the melted material then rises through the overlying Sangihe Plate as magma, fueling the volcanoes of the Sangihe Arc.
See also Eruption on Mount Lokon, Sulawesi, Eruption on Gamalama, Volcanic activity in the Halmahera Islands, Fresh eruption on Mount Karangetang, Indonesia and Volcanoes on Sciency Thoughts YouTube.
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