Gunung Agung volcano (Bali, Indonesia): flat lava dome occupying summit crater
Wed, 13 Dec 2017, 16:1016:10 PM | BY: T
A mass of flat, blocky lava - a lava dome - now occupies the crater of Mount Agung volcano, as photographed a few days ago (attached). Its volume is clearly less than previously estimated and it is far from filling the crater at the moment.
Picture of Agung's lava dome from 12 Dec 2017 (image: Aris Yanto / Ndeso Adventure)
An episode of moderate explosions and ash venting occurred yesterday and today, and likely has changed the volume / shape of the dome again.
In a recent statement, PVMBG talked about a "lava lake" (see note below), which emits persistent "flames" (glow from lava, incandescent gasses) at night. Three possibilities can happen:
- the eruption stops as no more gas is available to bring more magma to the surface and cause effusive / explosive activity
- little gas is available and continues to produce a mainly effusive eruption, i.e. lava is slowly rising and continues to accumulate with no significant explosions; in this scenario, the main danger would be if the summit crater fills up (which seems unlikely to occur)
- the lava freezes into a plug and gasses collect underneath, until a critical pressure build-up leads to a violent explosion.
Note: it is not a good idea to call this a "lava lake", as it normally involves more fluid lava in a still molten state able to produce convection, which is clearly not the case here. What the photo shows is similar to flat viscous lava domes such as the ones that Popocatépetl and similar volcanoes have been regularly effusing in their summit craters.
Wed, 13 Dec 2017, 13:00
Wed, 13 Dec 2017, 06:00
Agung volcano (Bali, Indonesia) - Smithsonian / USGS Weekly Volcanic Activity Report for 13 December-19 December 2017 (New Activity / Unrest)
PVMBG reported that during 13-19 December gray-and-white plumes rose as high as 2.5 km above Agung's crater rim and drifted W, N, and E; weather clouds and fog sometimes prevented visual observations. Incandescence from the crater was sometimes observed at night. The Alert Level remained at 4 (on a scale of 1-4), and the exclusion zones continued at a general 8-km radius and 10 km in the NNE, SE, S, and SW directions. ... Read all