Monday 9 September 2013

Explosive eruption on Mount Lokon.

Mount Lokon, a volcano close to the tip of Sulawesi's northern arm, erupted suddenly at about 6.30 am local time on Monday 9 September 2013 (about 10.30 pm on Sunday 8 September, GMT) producing a 1500 m high ash column in an explosive eruption that could be heard 10 km away, according to the Pusat Vulkanologi Dan Mitigasi Becani Geologi (Indonesian Centre for Volcanology and Geological Hazard Mitigation). This is the tenth such eruption since July this year, and a 2.5 km exclusion zone is currently being maintained around the volcano.

An eruption on Mount Lokon in July 2011. Reuters.

Lokon is a double volcano located near the eastern tip of the northern arm of Sulawesi, Indonesia. It has two cone-shaped peaks, Lokon to the southwest and Empung 2.2 km to the northeast, with a saddle of volcanic rock separating the two. Of these Lokon is the larger, though it has not erupted in recorded history, whereas the slightly smaller Empung last erupted in the late eighteenth century. Situated on the saddle between the two summits is Tompaluan, a double crater that remains active to the current day.

The Lokon-Empung volcanic complex is located at the southern end of the Sangihe Volcanic arc, where an extension Molucca Sea Plate is being subducted beneath an extension of the Eurasian Plate, sometimes called the Sangihe Plate. As this happens part of the subducting plate is melted by the heat of the Earth's interior, and rises up through the overlying plate as liquid magma, forming volcanoes at the surface. 320(ish) km to the east the Molucca Plate is also being subducted beneath an extension of the Philippine Plate, sometimes called the Halmahera Plate, producing a second chain of volcanoes in the Halmahera Islands. At some point in the future the Molucca Plate will vanish and the two volcanic arcs will meet.

The approximate location of Mount Lokon. Google Maps.

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