9 comments on “BAGANA – Bougainville Island, P.N.G.

  1. Hi agimarc, this may be something for you since you had written about Ilopango volcano:

    … The team discovered that the current tectonic stress field promotes the accumulation of magma and hydrothermal fluids at shallow (< 6km) depth beneath Ilopango. The magma contains a considerable amount of gas, which indicates the system is charged to possibly feed the next eruption. "Our results indicate that localised extension along the fault zone controls the accumulation, ascent and eruption of magma at Ilopango. This fault-controlled magma accumulation and movement limits potential vent locations for future eruptions at the caldera in its central, western and northern part – an area that now forms part of the metropolitan area of San Salvador, which is home to 2 million people. As a consequence, there is a significant level of risk to San Salvador from future eruptions of Ilopango."

    Paper: 'Magma storage in a strike-slip collapse caldera’ (open access PDF)

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  2. An image from an explosion at Sinabung today; this is not the first time that I noted the plume splitting in two in the upper part. Q.: is this caused by
    a) certain atmospheric conditions (wind, temperature)
    b) certain conditions inside the plume (composition, convection, turbidity)
    c) a second plume (not discernible in the lower part) ?
    I favor a) but does anyone know more?

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    • Howdy Granyia – Sinabung started this eruption sequence with dual plumes in late August 2010. Will upload a couple photos. Cheers –

      Double img removed/Gr

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    • And here goes Erik explaining my query in his latest Eruptions post.

      So, it is the neutral buoyancy which makes the various parts of a top of a plume drift apart. I knew about that but I thought it is only apparent in huge blasts where you get the “mushroom” top. Yes, logically, all ash particles must reach that state, in both small and big explosions. This photo from Popocatepetl (2016-08-15) shows the spreading very well:

      But still… in some plumes it looks as if they are splitting in quite low altitude. Perhaps there were more than one explosion in short sequence? This one from Santiaguito today (2016-08-18) for example, this looks very much like two separate plumes to me:

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  3. Fantastic article Granyia. Bagana was the first volcano that made me realise how rapidly cones can grow. Since then I have discovered a number of edifices that have been constructed very rapidly but I think Bagana still holds the record. It’ll be interesting to see what it does from here. Lava extrusion suggests there is not a lot of gas involved but that might change over time.
    I’m very impressed with your ability to find source material on such a remote volcano. I found it really difficult to find enough material on Rabaul and that is a far more well known volcano. Well done! A real joy to read.

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    • Hi Bruce, so good to hear from you, and thank you! Yes, it seems it is mostly the places where some foreign occupancy had taken place that you find written material (or even images) about. The locals probably had enough to do coping with the adverse conditions a volcano created for them than taking an interest in it.

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