Nishino-shima (Volcano Islands): The eruption on the remote island continues. The most recent overflight pictures by the Japanese Coast Guard show two active vents, one with a small lava-filled vent likely producing strombolian explosions, the other emitting a steam and gas plume.
At least some lava flows remain active and reach the coast, continuing to enlarge the island (visible by steam generated at the fronts).
Sakurajima (Kyushu, Japan): Following a week with no recorded vulcanian explosions, two relatively strong ones occurred this morning, producing ash plumes that rose to 11-12,000 ft (3.3-3.6 km) altitude. Since then, the Showa crater has been constantly venting ash.
Sinabung (Sumatra, Indonesia): VAAC Darwin raised the Aviation Color Code to “Red” after a possible major ash plume was spotted on satellite imagery. According to the original report, a possible ash plume rose to estimated 50,000 ft (15 km) altitude 12:32 UTC on 22 May and drifted SW. The height was later reduced to 35,000 ft (12 km).
It is unclear if the plume was a volcanic ash plume, in which case it would suggest a major explosion occurred at the volcano. However, VSI and local media did not report any usual activity at the volcano, suggesting that most likely the observed plume was from a storm cloud.
Merapi (Central Java, Indonesia): The Indonesian Volcanological Survey (VSI) lowered the alert level of Merapi back to “Normal” (1 out of 4). This decision came after signs of unrest had recently decreased again:
– Earthquake activity decreased both in number and type during the past weeks.
– Deformation data showed no inflation, but a currently stable behavior of the volcanic edifice.
– “No rumbles and booms were heard in the last 2 weeks”.
San Miguel (El Salvador): An eruption of the Chaparrastique volcano in the near future is becoming more and more likely. Tremor continues to rise and pulsating gas emissions have become stronger and sometimes contain small amounts of volcanic ash.
The increased tremor and gas emissions suggest movements of hot fluids (gasses, water, magma) into the volcano’s shallow plumbing system. MARN expects an eruption either from the central crater or a flank vent on the northern side (where most microseismic activity has been focused).
According to SNET, the fine ash that was observed during recent days was “juvenile”, i.e. originating from fresh magma (as opposed to fragmented old material). Technically, the volcano is therefore already in eruption.
More at Volcano Discovery: Volcanoes Today, 23 May 2014: Merapi, Sinabung, Sakurajima, Nishino-shima, San Miguel