8 February 

Daily volcano update


25 seismic events were recorded by the monitoring equipment on Gunung Agung yesterday, including:

  • Blowing tremors (5) indicating the release of gasses from the magma within the volcano.
  • Shallow (10)
  • Deep (7) volcanic earthquakes. Volcanologists, now, believe Gunung Agung have two magmatic chambers under the mountain.
  • One deep at 22-24 km under the mountain
  • One shallow at around 4 km.
  • These volcanic quakes indicate magma moving around.

The seismogram shows two overscale tremors yesterday at 10:20 and 12:19 – one blowing tremor before noon, and a good-sized earthquake (4.6 on the Richter scale) in West Sumbawa. Reminder, overscale red marks result when the amplitude is greater than 20 mm (the recording limit on the seismograph).

I’ve changed the chart to make it more readable – it now includes approx. 3 weeks of data to enhance the detail. PVMBG has not reported continuous microtremors since 05 Feb, which I assume is because they are often the result of external activities and not the volcano. Total numbers before 05 Feb included these, so were slightly larger.

Petra Stahly’s beautiful photo is accompanied by one from Amed this morning at 07:48 showing a weak plume drifting to the east. Don’t become complacent.

Several people last night asked about the “new status” of the mountain based on the discussion they had picked up from some other groups. FYI, PVMBG currently puts Gunung Agung at LEVEL IV, and the exclusion zone REMAINS AT 6 km from the crater. Monday press reports quoted I Gede Suantika, Head of Mitigation at PVMBG, as saying that given the low levels of activity seen in the volcano recently, *the next full evaluation* might result in a lower status level. A full evaluation is a comprehensive analysis and it typically takes about a week to collect the satellite, ground and gas data from local and international sources.

BPBD’s report yesterday on evacuees: 181 evacuation posts (-0 from the previous day) counted 19,936 evacuees registered (-323). Roughly 17,000 people are estimated to reside in the 6 km exclusion zone.

Darwin VAAC does not show Agung on the map, nor does FlightRadar24 (which imports the data from the VAAC) – no airborne ash can be identified. Windy.com says the air currents now are generally to the east from the surface to around 5,000 meters (up to the top of a good-sized ash column), and then swing around towards the southwest at higher elevations. Airport operations are currently normal.

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