Eruption of the volcano continues. Ash explosions up to 10 km (or 32,800 ft) ASL possible at any time. Ongoing activity could affect international and low-flying aircraft.

A danger of catastrophic eruption exists.

Strong explosive eruption of the volcano began at 19:57 UTC on December 12 and continued during 20 minutes. A height of ash explosions was about 3.0-3.5 km (9,840-11,500 ft) ASL but strong wind whirled ash plume to the north-west. Lightnings was observed into ash explosions. Too much steams obscured the volcano after explosions. Ashfalls occurred in the villages Kozyrevsk (110 km from the volcano) and Tigil (308 km from the volcano). Color of ash was grey. Smells of sulfur perceptible in air. The thickness of ash layers were 0.5 cm at Kozyrevsk (ash falls from 21:00 till 21:30) and 0.5 cm at Tigil (ash falls from 23:30 till 24:00). According to satellite data (MTSAT), a compact circle ash cloud in diameter about 90-120 km extending to the N-W from the volcano were noted from 20:30 till 21:30 UTC on December 12.

From about 23:13 UTC on December 12, an amplitude of volcanic tremor began increased. Probably strong explosive events will continues.

Large volcanic convulsions of fire, ash, and vapor appear intuitively to be too energy-intensive to be explained without a chemical reaction of combustible gas. Among combustible gases, methane, and hydrogen sulphide are widely recognized as components in volcanic eruptions. They produce heat on combustion, but not the ash that only silane can produce. The arguments for silane then are that the great blankets of siliceous ash observed worldwide require silane to explain their provenance and correspondingly large releases of energy to create them. Other metal hydrides in the silane-dominated effusion can provide the complement of minor metals found in ash and tephra, but only silane can produce the dominant silica.