Batu Tara, Komba Island, Indonesia

Batu Tara is another volcano that caught my eye while looking at volcanic ash alerts from Darwin VAAC [1] for Mount Sinabung (Darwin VAAC is having a busy time). Batu Tara is frequently active, producing ash eruptions rising to hundreds or few kilometres.

Fig 1: Eruption on Batu Tara.  Photo by Debbie Arriaga, Arenui Boutique Liveaboard. ©Debbie Arriaga, 2014. All rights reserved. Reproduced with kind permission from the photographer.

Fig 1: Eruption on Batu Tara. Photo by Debbie Arriaga, Arenui Boutique Liveaboard. ©Debbie Arriaga, 2014. All rights reserved. Reproduced with kind permission from the photographer.

Fig 2:  NASA stallite image published under Wiki Commons.  Source: http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=43158&src=nha

Fig 2: NASA stallite image published under Wiki Commons. Source: http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=43158&src=nha

Batu Taru is an uninhabited island is in the Flores Sea. With a summit of 748 meters above sea level, she is the aerial part of a stratovolcano whose base is three kilometres below sea level. She has a large central summit crater of 900 meters by 700 meters diameter open to the east. On her eastern side is a flank collapse feature [2].

Her major rock types are Trachybasalt / Tephrite Basanite, Trachyandesite / Basaltic trachy-andesite. She is noted for potassic leucite-bearing basanitic and tephritic rocks [2].

Fig 3:  Satellite image taken on 15 August 2012 showing the collapse scar.  NASA image by Jesse Allen and Robert Simmon using EO-1 ALI data.  Source:  http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=78886

Fig 3: Satellite image taken on 15 August 2012 showing the collapse scar. NASA image by Jesse Allen and Robert Simmon using EO-1 ALI data. Source: http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=78886

Eruptive History

Not much is known about Batu Tara’s eruptive history. The only confirmed historic eruption was a VEI-2 during 1847 -52 that produced explosions, volcanic bombs and a lava flow.   On 1 July 2006, she started to erupt again (VEI-1) with an ash plume that rose to 5,000 ft. She has been erupting frequently since. Her eruptions have been strombolian or vulcanian. In March 2007, she had a series of stronger eruptions (VEI-2), which led to the evacuation of 15,000 people from Lembata Island, 50km to the south [2,3].

 

Tectonic Setting

Batu Tara’s tectonic setting is ocean crust subduction zone [2]. She lies in the Eastern Sunda Arc, Indonesia, on young and thin oceanic crust north of the main volcanic Sunda-Banda Arc. She is near the convergent boundary between the Banda Sea Plate and the Timor Plate, north of the Australian Plate. The area is seismically very active, with many volcanoes and many large earthquakes [3].

Fig 4:  Banda Sea Plate (“Mer de Banda”), Timor Plate and Australian.  Published under Wiki Commons. Source: http://en.wikipedia.org/wiki/Banda_Sea_Plate

Fig 4: Banda Sea Plate (“Mer de Banda”), Timor Plate and Australian. Published under Wiki Commons. Source: http://en.wikipedia.org/wiki/Banda_Sea_Plate

Batu Tara, herself, is north of the main volcanic arc, which formed in the Miocene about 15 million years ago as a result of the collision between the Asian and Australian plates. We can see the subduction of the Australian Plate in the next three images of the five thousand most recent earthquakes in the area:

Fig 5:  Most recent 5,000 earthquakes (to 25 May 2014) from IRIS.  Source: http://www.iris.edu/ieb/ . Batu Tara is the tiny island west of the orange coloured earthquake in the red ellipse.

Fig 5: Most recent 5,000 earthquakes (to 25 May 2014) from IRIS. Source: http://www.iris.edu/ieb/ . Batu Tara is the tiny island west of the orange coloured earthquake in the red ellipse.

Fig 6:  Depth v Longitude (colours denote depth) by the author.  Copyright rests with the author and reproduced with kind permission of the author.

Fig 6: Depth v Longitude (colours denote depth) by the author. Copyright rests with the author and reproduced with kind permission of the author.

Fig 7: Depth v Latitude (colours denote depth) by the author.  Copyright rests with the author and reproduced with kind permission of the author.

Fig 7: Depth v Latitude (colours denote depth) by the author. Copyright rests with the author and reproduced with kind permission of the author.

Batu Tara, herself, is about 230 km above the Benioff zone [5] for the subducting Australian Plate. , but, given the proximity of the Timor and Banda Sea Plates, sources for her magma may be more complex. Studies of her lavas do indicate parental magmas with different origins: subducted sedimentary/crust in addition to both mid ocean ridge basalt (MORB) and ocean island basalt (OIB). Partial melt of crust-contaminated MORB mix in the mantle wedge with partial melts of OIB domains. Potassium enrichment is attributed to both enriched mantle and subducted crustal materials [6,7].

Hope you enjoyed reading this. The usual caveats apply: “not an expert”, etc.. And if you would like to know more about the kind people who provided the photograph of the eruption at Batu Tara, Arenui Boutique Liveaboard, please visit their Facebook page: https://www.facebook.com/ArenuiBoutiqueLiveaboard

KarenZ, 26 May 2014

 

References

  1. Darwin VAAC: http://www.bom.gov.au/info/vaac/
  2. GVP: http://volcano.si.edu/volcano.cfm?vn=264260
  3. Volcano Discovery: http://www.volcanodiscovery.com/indonesia/batutara.html
  4. Banda Sea Plate: http://en.wikipedia.org/wiki/Banda_Sea_Plate
  5. “The geochemistry and petrogenesis of K-rich alkaline volcanics from the Batu Tara volcano, eastern Sunda arc” A. J. Stolz, R. Varne, G. E. Wheller, J. D. Foden, M. J. Abbott, Contributions to Mineralogy and Petrology, March 1988, Volume 98, Issue 3, pp 374-389 http://link.springer.com/article/10.1007/BF00375187
  6. “The origin of the potassic rock suite from Batu Tara volcano (East Sunda Arc, Indonesia)” M.J. van Bergen, P.Z. Vroon, J.C. Varekamp, R.P.E. Poorter, Lithos, Volume 28, Issues 3–6, November 1992, Pages 261–282, Potassic and ultrapotassic magmas and their origin, http://www.sciencedirect.com/science/article/pii/002449379290010V
  7. “Volcanism and tectonics in the Eastern Sunda Arc, Indonesia”, J.C. Varekamp, M.J. Van Bergen, P.Z. Vroon, R.P.E. Poorter, A.D. Wirakusumah, R. Erfan, K. Suharyono, T. Sriwana, Netherlands Journal of Sea Research, Volume 24, Issues 2–3, November 1989, Pages 303–312, http://www.sciencedirect.com/science/article/pii/0077757989901567
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54 thoughts on “Batu Tara, Komba Island, Indonesia

  1. At first I got really confused because I thought you were talking about Paluweh so I went to check. There appear to be a lot of similarities between the two .. they are in fact only a couple of hundred km apart in the same setting. Indonesia is simply awesome. Nice article Karen!

  2. Bit of an OT, but spent the last week down in Venice visiting my sister and brother and law and the Architecture Biennale. While going through the Italian exhibition I stumbled on this:
    Pompeii housing materials

    • perhaps not that interesting, I was just fascinated by the amount of volcanic material that had gone into the construction of the house.

  3. Next person to get socially lynched: Jan Smeets, the organisator of the pinkpop festival in Dutch Limburg.

    At pinkpop, metallica was planned to give a show for 60 000 men at this moment.
    Only problem: there is a severe weather warning for the Benelux:

    from estofex this morning ( http://estofex.org/ )
    A level 3 was issued for NW France and BENELUX for very large hail, damaging wind gusts, tornadoes and excessive precipitation.

    So what does Mr Smeets (and others who are responsible)? This afternoon, he says that there is nothing wrong and the show can go on: the thunderstorms will only come after pinkpop ends and there are more than enough lightning rods on the festival site. Ofcourse thunderstorms don’t follow Mr smeets planning and went straight towards the festivalsite. This was already absolutely clear at 16 h local time. Smeets opted for the lets wait and hope that nothing will happen strategy. He only came back on his words when the thunderstorm is 5 minutes away from the festival. So he gives 60000 people in open grasslands the advice to squat down and keep away from tents and trees. He also started to evacuate the camping at that moment:

    The sky is black in the movie because the clouds are over 14 km high, normally it would be near sunset now. (daylight). Also in this massive thunderstorm, there was an activity measured of 100 lightnings/minute. The nearest weather station has a TT value of 55,3 . The TT value is a way to show the probabilty on thunderstorms. A TT value between 53-56 means: everywhere heavy T-storms, TT above 56 means: run for your live.

    I hope that that they get lucky and nobody gets hurt (the heaviest part of the storm seems to miss the festival ground by a few km)

    • The whole weekend, we have had locally massive and very damaging thunderstorms in the area (hail >5cm, floodings, windgusts over 80 km/h etc.). So the organisators were warned. This was Saturday evening (ad this was of the storms with only minor damage)

      and this map shows all the lightnings from 0:00 today. ( 80 000 and counting) Pinkpop is in the pink part. (near Maastricht)

      http://nl.tinypic.com/?t=postupload

      • Not if you’re driving through it. As for Metallica, I do care about them. If they choked on their guitar picks live on stage, I might pay to watch that, as long as there was a band body count afterwards, just to make sure that none of them got away.

  4. BTW, very interesting article KarenZ, you can trust the Indonesian volcanoes to keep things interesting. I just had to write it off.

  5. I live in Florida. We don’t have volcanoes, other than the occasional 60 million year old extinct edifice buried under several km of sediment. We do have Hurricanes… but there are also other less apparent hazards here… He was bass fishing, and yes, that is a treble hook.

    • some people will go to no length to get an original piercing….. 😀
      But he was really lucky this time. Should fishers use safety goggles ?

      • Up here hats and glasses of some sort are highly recommended, as when the hook comes out of a salmon, it travels back to the fisherman at a high rate of speed. Sometimes you end up wearing it. Most of us learn how to duck the projectile. Cheers –

      • Well, I don’t freshwater fish, on occasion I do saltwater fish from the muni pier/quaywall down town. The worst that I have done is to catch a Pelican. I got my hook back, and the bird survived, only to continue menacing the other fishermen’s bait. (along with the other pelicans) At first, I thought the bird had shit all over my hands, but the brown gook was oil.

        Pelican’s are just one of the hazard to fishing with live bait. Since I use a six foot steel leader, the bait fish is always swimming around pretty close to the surface. The steel leader is to keep the Mackerel from tail whipping the line and getting away. The other hazard is the various bait fish tangling the lines as they wander back and forth. One of the entertaining aspects of watching the fishermen there is them trying to walk their bait in and around each other. Think about that. Grown men, walking fish.

    • I’m not gonna follow this up with aknowlegements one way or the other. Other than to note that this is Florida. Its a friend of the grandkid’s.

      I wonder just hos florescent that worm is. Might look quite spiffy on the dance floor with the glow-stick crowd.

  6. … meanwhile, Rates and Processes of Potassic Magma Evolution, The Journal of Petrology, Turner et al (2002) seems to point towards a chemistry at Batu that could be characteristic of the Mantle Plume meme. See pg 504 of the document (pg 14 of the pdf)

    On occasion, mantle plumes have been invoked to explain the high level of volcanism for wide expanses of the West Pacific, and the somewhat odd chemistry of a residual plume could help to explain Batu’s presence over a deeper part of the Wadati–Benioff zone (280 km) than would ordinarily be expected. Typically, around 110 to 125 km is where the magma seems to percolate off of the subducting slab and where the arc volcanism tends to show up at.

    But… mantle plumes are somewhat contentious in many circles. They can explain a lot, but they are not a panacea.

    • I am reading “Volcanoes of the Solar System” by Charles Frankel, Cambridge University Press, 1996. In it Frankel says that, in relation to subduction of the Nazca plate under the American plate, “volcanism is greatest where the dip angle of the subducting plate is greatest, resulting in deep source alkaline magmatism comparable to that of incipient hot spot” (page 38).

      Something akin to this may be happening under Batu Tara – the dip angle of the subducting plate seems to increase. 230km (280km or even 380km depending on the paper) seems to refer to the Australian plate. There are other plates in the area which may provide a shallower source for magma nearer to the expected 150km for a subduction zone. We would need to plot more earthquakes to get a better picture of what is happening.

      Or there could be a weak spot in the ocean crust as a result of the movement of the micro-plates / plates. Extensional tectonics could provide cracks where the magma can get through more easily.

      • Sounds like a nice little summer science project to plot the subducting plate. 🙂

        Looking forward to your plotilicious results!

        • Plotting the subducting plates for Indonesia is not as straightforward as you might imagine 😉

          But I am working on one already …..

          • Well doing the plots is not too bad; it is working out what you have plotted so you can verify the plot afterwards that is more complicated.

            • Well, I have “found” a subduction zone that the maps don’t have on them. So I’ll have to dig around the research papers a bit to see what it is.

  7. Pingback: Batu Tara, Komba Island, Indonesia | VolcanoCafé | Arenui – Indonesia's Boutique Liveaboard

  8. Nice new batch of deeper quakes in the same region below Katla. One was at 40km yester haha 😀 They might really not mean anything at all, but its cool to see it. 🙂

      • The ocean will survive. It will become part of a reef eventually…. or subducted/pushed up into a mountain arc. As noted in the video, some hapless geologist will find it in the future and after the intial “WTF?” character clears out, it will be a horizon that marks this era. Hell, we could even become an easily recognizable boundary for the transition from Homo Sapiens to Homo Stultus.

  9. From the USGS in a narrative about a recent quake:

    “Before collision began, the Sunda subduction zone extended eastward to at least the Kai Islands, evidenced by the presence of a northward-dipping zone of seismicity beneath Timor Leste. A more detailed examination of the seismic zone along it’s eastern segment reveals a gap in intermediate depth seismicity under Timor and seismic mechanisms that indicate an eastward propagating tear in the descending slab as the negatively buoyant oceanic lithosphere detaches from positively buoyant continental lithosphere. On the surface, GPS measurements indicate that the region around Timor is currently no longer connected to the Eurasia plate, but instead is moving at nearly the same velocity as the Australia plate, another consequence of collision. ”

    Hello plate shard

    Timor is about 184 km southeast of Komba Island on the other side of the island of Lambata and Alor islands.

    East Timor is where there has been clashing of opposing people in the last few years… which is a bit odd, the root word that the name Timor comes from “timur” mean’s “east” in Maylay, so it’s technically “East East.”

  10. And in regards to the Leucite at Batu Tara…

    “For the presence of this mineral it is necessary that the silica percentage of the rock should be low, since leucite is incompatible with free quartz and reacts with it to form potassium feldspar. Because it weathers rapidly, leucite is most common in lavas of recent and Tertiary age, which have a fair amount of potassium, or at any rate have potassium equal to or greater than sodium; if sodium is abundant nepheline occurs rather than leucite.”

    Source → Whackyerpedia.

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