OverviewGunung Karangetang, also known as Api Siau, is a highly active and fairly remote volcano on Siau island of the Sangihe Islands group in the province of North Sulawesi, Indonesia. Karangetang can be climbed in one long day, although this is not advisable due to the significant risk of dangerous volcanic activity. However, short trips to old lava flows on the lower slopes during quiet times are safe and offer great views of the mountain.
Getting ThereThe regional starting point for a trip to Gunung Karangetang is the provincial capital Manado. Manado is linked by air to all major cities in Indonesia as well as Singapore and Davao in the Philippines. From Manado one takes a ship to the small port of Ulu on Siau island. There are crowded overnight ships as well as the faster daytime Express Bahari boats. Both types of ships run three times a week and leave from Manado's main harbor. Basic accommodation is available in Ulu. From Ulu, day trips to old lava flows on the lower flanks of the volcano can be arranged.
Volcanic ActivitySeveral types of volcanic activity may be encountered on Karangetang. While the more violent ones are mostly confined to obvious eruptions that occur in blocks of up to a few weeks about once a year, all may occur at any time, including during quiet phases of seemingly low activity.
Degassing of mostly white volcanic gases of sulfur dioxide and water vapor happens near continuously at the craters. Exposure is limited to the summit area.
Strombolian explosions shower an area of up to several hundred meters from the craters with lava bombs and blocks and can happen with little warning.
Lava or rock avalanches occur when material breaks off of instable parts of the summit lava dome or active lava flow fronts and descends down the flanks at high speed.
Pyroclastic flows form as a result of larger collapses of parts of the summit lava dome or active lava flow fronts and in addition to glowing boulders also contain hot ash and volcanic gases racing down the flank of the volcano.
Brief exposure to sulfur dioxide is usually harmless, but for durations of a few minutes or more, a piece of cloth or a gas mask are advisable. With the exception of quiet degassing, a close encounter with any of the above types of activity would likely end fatally. The effects of explosions are limited to the summit region. A helmet should be worn there. Lava and rock avalanches as well as pyroclastic flows can travel up to several kilometers and the risk of getting caught in one can be somewhat reduced by staying on higher ridges. There are no such ridges in the summit area.
RoutesIt is strongly advised not to attempt to climb Gunung Karangetang due to the volcanic dangers described above.
That being said, if you really need to go, the trip to the top and back can be made in one long day if the mountain is in a quiet phase and the weather is favorable. Note that even during a quiet phase sudden explosions or rockfalls are possible with little or no warning. The chances of finding a local who is willing to take the risk to show you to the top are very slim, but finding a guide to take you through the plantations and jungle to the bottom of an old lava flow is fairly easy. You could then take the lava flow and lava fields up to the top. There are no paths beyond the coconut plantations on the lower flanks, so make sure you got your navigation sorted out, especially on the way back down. Once you are up there, everything looks the same and visibility is often hampered by clouds. Two possibilities are an old lava flow on the southeastern flank near the village of Dame as well as one on the south flank. If climbing from the southeast, one needs to keep to the left (south) in order not end up on the lower second summit/crater.
Red TapeWe are not aware of any official rules. There is a manned volcano monitoring station in Salili south of the mountain. They have a seismograph and can tell you about current activity levels, but it may not be the smartest move to inform them of any plans you may have to climb to the top.
When To GoOnly attempt to summit during long quiet phases of volcanic activity, if at all. During significant eruptions, even the lower flanks may be dangerous due to pyroclastic flows and going anywhere near the summit would be suicide. As for the climate, temperatures are almost constant year round. The driest months around Manado are July through September, but the islands are mostly wet year round. The best chances of a cloud-free summit are in the very early morning. Be prepared for heavy downpours especially on the lower flanks.
External LinksKarangetang page of the Global Volcanism Program of the Smithsonian Institution
Karangetang page at Volcano World