After a few months of intermittent explosions since late 2010, Bulusan in the Philippines looks to be at it again (although not really a "major volcanic eruption" as the Huffington Post claims). The volcano produced a 3 km / 9,800 feet plume (top left) while the Tokyo VAAC is warning of ash as high as FL120 (3.6 km / 12,000 feet) - you can check out another shot of the plume here. Noise from the explosion was heard up to 10 km from the volcano PHIVOLCS director Renato Solidum says the eruption was another phreatic (steam-driven) event, however at this point it is unknown if the ash is still only accident (old) fragments or juvenile magma. This explosion appears to have been unexpected as the last Bulusan update from PHIVOLCS said there had been no seismicity at the volcano. So far, though, it looks like this eruption is on par with what we've been seeing since the fall. PHIVOLCS have kept the Alert Level at Bulusan at Level 1 with a 4-km exclusion zone near the volcano.
Bulusan in the Philippines erupting on February 21, 2011.
UPDATE (2/21/2011): It appears that the series of explosive events on Monday (see above) have prompted the Philippine government to call for ~2,000 people to evacuate the area closest to the volcano. Ash from the eruption fell on over 17 towns that are populated by over 100,000 people, just to give you an idea of the population near Bulusan. The Philippine government has also declared a "no-fly" zone around the volcano due to the threat of new explosions.
Top left: Image of the February 21, 2011 plume from Bulusan in the Philippines. Click here to see the original.