Mount Dukono, (1° 41′ 0″ N, 127° 53′ 0″ E)
I became interested in Mount Dukono after seeing several volcanic ash alerts for her from Darwin VAAC  while looking at alerts for Mount Sinabung. My internet searches, mostly Wikipedia, and earthquake graphing, led from Mount Dukono to a very lively tectonic setting.
Mount Dukono is one of Indonesia’s most active volcanoes. She is a complex volcano in a compressional oceanic setting, with seven craters: Tanah Lapang, Dilekene A, Dikekene B, Malupang Magiwe, Telori, Crater E, and Heneowara [2,3,4]; and, an ash desert.
Mount Dukono is remote, located in the north of Halmahera Island , one of the Spice Islands (Maluka Islands) in east Indonesia.
Halmahera Island is made up of metamorphic, volcanic and sedimentary rocks: Paleozoic metamorphic rocks; Cretaceous ultramafics and ophiolites; Tertiary andesites, basalts, dacite , rhyolites, clastic sediments and limestone; and, Quaternary flows, tuffs and ignimbrites . A geology that is characteristic of a collision or subduction zone.
According to GVP, recent eruptive activity has been: 15 November 1550 VEI 3; 1719; 1868 VEI2; 1901 VEI 2; and, 13 August 1933 VEI3 (still continuing) .
Mt Dukono’s eruptions tend to be explosive, sometimes with lava flows. Her lavas are: andesite / basaltic andesite; trachyte / trachyandesite; and, basalt / picro-basalt . During the 1550 eruption, the strait between Halmahera and Gunung Mamuya filled with lava . Activity in 2014 to the time of writing has been frequent but moderate. The maximum plume height reached so far this year as reported by Darwin VAAC is 14,000 feet 
A rough estimate by the author of the eruption volume is shown in this graph using plume heights from Darwin VAAC  and a formula from L.G. Mastin et al :
Compare this to a rough estimate of the eruptive volume of the recent eruption of Mt Kelud:
The Maluku Islands are located on the Halmahera Plate which is at the meeting point of four geological plates and two continental blocks.
The Molucca Sea is tectonically very active. Clearly, an incentive to do a bit of earthquake graphing!
The graph shows the earthquakes from 31 March 1994 to 30 March 2014 as reported by USGS . You can see the subduction zone in the top left of the graph. However, something looks a bit unusual here: Mt Dukono is to the east of the subduction zone and, at first site, appears to be on the subducting plate.
But take a look at what’s going on underneath the ground, there is a second subduction zone.
The subduction zone to the west (left in the above graph) is the Sangihe subduction system ; and, the second one to the east (right in the above graph) is the Halmahera subduction system . This is the only known example of the collision between two active arcs in an ocean basin. The collision zone is the Molucca Sea Collision Zone : the two subduction systems appear to have fully subducted the oceanic lithosphere of the Molucca Sea plate ; and, the Sangihe arc now over-rides the Halmahera forearc.
This is what the collision zone looks like on the surface:
Maju Island is one of the islands at the surface (A and B are two data points from the top of the meeting point of the two collision zones so I could find it on the map). Maju Island may be volcanic but she is eluding internet searches so far (I have not tried Google Scholar yet) ….
Hope you enjoyed reading this. The usual caveats:” Not an expert” apply.
Now I am off to the bar for a recuperative drink. See you there! ☺
KarenZ, March 2014
Sources & References:
- Satellite images of Dukono: Geological Survey of Japan, AIST,2014, Image Database for Volcanoes, https://gbank.gsj.jp/vsidb/image/index-E.html
- GVP: http://www.volcano.si.edu/volcano.cfm?vn=268010
- Dukono: http://en.wikipedia.org/wiki/Dukono
- John Search: http://www.volcanolive.com/dukono.html
- Halmahera Island: http://en.wikipedia.org/wiki/Halmahera
- Dukono, Halmahera Arc Volcanoes, Indonesia: http://volcano.oregonstate.edu/oldroot/volcanoes/dukono/dukono.html
- Plume heights: Darwin VAAC: http://www.bom.gov.au/info/vaac/advisories.shtml
- Formula for eruption volumes: Mastin, L.G. et al., “A multidisciplinary effort to assign realistic source parameters to models of volcanic ash-cloud transport and dispersion during eruptions”, Journal of Volcanology and Geothermal Research (2009), doi:10.1016/j.jvolgeores.2009.01.008
- Background image: Dukono’s main crater: Grant Davey, published under Wiki Creative Commons licence v2.0: http://commons.wikimedia.org/wiki/File:Mt_Dukono.jpg
- Background image: Kelud’s lava dome came from here but the webcam did not survive the eruption: http://vsi.esdm.go.id
- Halmahera Plate: http://en.wikipedia.org/wiki/Halmahera_Plate
- Map of the tectonic plates by Sting and Rémih: http://en.wikipedia.org/wiki/File:Molucca_Sea_Plate_map-fr.png
- USGS: http://earthquake.usgs.gov/earthquakes
- Sangihe Plate: http://en.wikipedia.org/wiki/Sangihe_Plate
- Molucca Sea Collision Zone: http://en.wikipedia.org/wiki/Molucca_Sea_Collision_Zone
- Molucca Sea Plate: http://en.wikipedia.org/wiki/Molucca_Sea_Plate