Visually, no visible change in the color and height of emissions, but the smoke was observed with increased violence following pressure under solfatare of Egon. The color of the smoke of the solfatares is white and rise to an average height of 25-50 meters above the summit. The gusts generated by the increase in energy supply tends to fluctuate. On January 16, 2016, around Mainstay, about 2.5 km from the top of Mount Egon, SO2 levels were measured with the amount of 12 ppm , with 8 ppm of H2S and 0.6% of CO2 (6000 ppm). The maximum level safe for humans is 2 ppm of SO2, 10 ppm of H2S for a period of 8 hours, and 0.5% or 5000 ppm of CO2. Therefore, the levels of SO2 and CO2 are above safe levels, so there is the potential threat of poisonous gas in a radius of 3 km.
The volcanic seismicity of the Egon is dominated by the earthquake (VA), harmonic tremors, and emission earthquakes. After an increase in activity level on 12 January 2016, the number of seismic events of Egon tended to decrease. However, seismic analysis charts show that, despite the relative decline in the number of earthquakes, the cumulative amount of seismic energy is relatively more important. RSAM graph shows a decrease in activity after three strong periods, on December 18, 2015, December 22, 2015 and January 12, 2016. The recorded presence composed of tremor, low earthquake and high frequency, indicating a flow of fluid magma towards the surface with rock fracturing process.
In general, the type of eruption of Mount Egon is phreatic. This type of eruption can occur if there is an interaction between magma and water beneath the surface (hydrothermal), which leads to changes in the liquid phase passing in vapor, producing changes in the volume, which can push the cover of rock near the surface of the crater. The symptoms currently observed are identical to the symptoms of increased seismic activity before the eruption of Mount Egon on April 15, 2008, an increase of seismicity which lasted a relatively short time. Although for now, it can be established that the eruption of Mount Egon is imminent, the anticipation efforts and disaster mitigation efforts need to be improved.
Based on visual observations, seismicity, RSAM measures and the potential threat of eruption of Mount Egon until the date of 20 January 2016, the level of volcanic activity of Mount Egon remains at LEVEL III (Siaga).
If there is a decrease / increase in volcanic activity changes significantly, the activity level can be lowered / raised in accordance with the level of threat.
January 23, 2016. Egon, Indonesia :
Source : VSI
Photos : Aquatravel.cz,