Llaima in Chile erupting in 2009.
A quick note to pass along about the ongoing eruption at Llaima in Chile. The eruption did seem to be waning earlier in the week, but the news now is that debris from the eruption is partially blocking the vent. The cone of pyroclastic material (tephra) that has been ejected during the eruption is now overlapping the main crater, potentially blocking part of the vent ... and most people know what happens if you plug up a volcano that is actively erupting - blammo!
The SERNAGEOMIN is not certain that this cone of material (in spanish) will cause a more intense explosion due to pressure building from the blocked vent, but it is a potential event. This eruption has already spread ash over a wide region of Chile and caused the evacuation of people near the volcano. Right now, the SERNAGEOMIN is keeping the volcano on Red Alert (obviously), but we'll have to keep a close eye on how this development changes the eruption over the next few days.